Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at
http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz
http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src
the tree for the Cog generated sources including all plugins
stacksrc/vm
the directory containing the Stack VM source (plugins can be taken from above)
platforms
the usual svn platform tree but including Cog specific changes such as the heartbeat
processors
the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image
the Cog-prepared Squeak 4.1 VMMaker image
scripts
some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild
the win32 build directory
winbuild
the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin
macbuild
the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better
unixbuild
the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status:
The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT):
All contributions from Teleplace in this release are
Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Eliot Miranda
June 2010
Eliot,
this is absolutely wonderful news. Thank you and everyone at Teleplace who made this possible.
Best wishes,
Michael
On Sun, Jun 20, 2010 at 10:11 PM, Eliot Miranda eliot.miranda@gmail.com wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at
http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz
http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src
the tree for the Cog generated sources including all plugins
stacksrc/vm
the directory containing the Stack VM source (plugins can be taken from above)
platforms
the usual svn platform tree but including Cog specific changes such as the heartbeat
processors
the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image
the Cog-prepared Squeak 4.1 VMMaker image
scripts
some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild
the win32 build directory
winbuild
the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin
macbuild
the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better
unixbuild
the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status:
The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT):
All contributions from Teleplace in this release are
Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Eliot Miranda
June 2010
Hi Eliot:
Thanks you very much (and also to the Teleplace people) by share this really big step in the VM area.
Excellent news to this sunday!!
2010/6/20 Eliot Miranda eliot.miranda@gmail.com:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at
http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz
http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src
the tree for the Cog generated sources including all plugins
stacksrc/vm
the directory containing the Stack VM source (plugins can be taken from above)
platforms
the usual svn platform tree but including Cog specific changes such as the heartbeat
processors
the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image
the Cog-prepared Squeak 4.1 VMMaker image
scripts
some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild
the win32 build directory
winbuild
the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin
macbuild
the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better
unixbuild
the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status:
The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT):
All contributions from Teleplace in this release are
Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Eliot Miranda
June 2010
This is really an excellent news. I open a lot of new futures! Thanks teleplace, andreas and all the people that helped.
Stef PS: you already answer my questions about platform were the jit cannot work so this is great.
On Jun 20, 2010, at 10:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src the tree for the Cog generated sources including all plugins stacksrc/vm the directory containing the Stack VM source (plugins can be taken from above) platforms the usual svn platform tree but including Cog specific changes such as the heartbeat processors the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image the Cog-prepared Squeak 4.1 VMMaker image scripts some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild the win32 build directory winbuild the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin macbuild the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better unixbuild the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT): All contributions from Teleplace in this release are Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Eliot Miranda June 2010
Thank you Eliot.
This is wonderful, it feels like I just got a new laptop :-)
I noticed some problems in the continuation tests of Seaside (WAContinuationTest, WAFlowPlatformTest and WAPartialContinuationTest):
"Computation has been terminated" in MethodContext>>cannotReturn:
Is this a known problem? Or is this maybe specific to Pharo on Cog?
Cheers, Lukas
On 20 June 2010 22:53, stephane ducasse stephane.ducasse@gmail.com wrote:
This is really an excellent news. I open a lot of new futures! Thanks teleplace, andreas and all the people that helped.
Stef PS: you already answer my questions about platform were the jit cannot work so this is great.
On Jun 20, 2010, at 10:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src the tree for the Cog generated sources including all plugins stacksrc/vm the directory containing the Stack VM source (plugins can be taken from above) platforms the usual svn platform tree but including Cog specific changes such as the heartbeat processors the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image the Cog-prepared Squeak 4.1 VMMaker image scripts some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild the win32 build directory winbuild the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin macbuild the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better unixbuild the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT): All contributions from Teleplace in this release are Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Eliot Miranda June 2010
On Sun, Jun 20, 2010 at 2:23 PM, Lukas Renggli renggli@gmail.com wrote:
Thank you Eliot.
This is wonderful, it feels like I just got a new laptop :-)
:)
I noticed some problems in the continuation tests of Seaside (WAContinuationTest, WAFlowPlatformTest and WAPartialContinuationTest):
"Computation has been terminated" in MethodContext>>cannotReturn:
Is this a known problem? Or is this maybe specific to Pharo on Cog?
This is a known area of problems. From my announcement:
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (*for example I know that co-routining does not yet work*). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
The use of context-to-stack mapping is fundamental to the performance improvements in Cog and it *should* be transparent, but so far I've only fixed what issues we've encountered in our usage at Teleplace. I expect the next few weeks to involve some bug fixing as it is used in a much broader context (no pun intended). Y'all can help by giving me reproducible test cases. This can be in the form of a precise specification of an image configuration and a doit, but even easier is to save an image that exhibits the crash on start-up. e.g. Smalltalk saveAs: 'crash.image' thenQuit: true. MyClass crashTheVM
I also need to write the sequence of blog posts on the JIT I've been meaning to write for over a year now, as others will want to understand and, I hope, port Cog to other processors.
There's also the need to improve performance. Right now the code generator is a very naive JIT where every there is no inter-bytecode optimization and hence every push or pop in the bytecode is reflected in a real push or pop in the native code. This makes loops such as 1 to: n do: [:i|... ] very slow because the send: #<= (1 arg); jumpFalseTo: L2 in the underlying code actually runs a non-inlined SmallInteger <= primitive which pushes the actual true object, which the jump bytecode must compare against the actual true false object. In the VisualWorks code generator the JIT spits out two paths here, one that tests or SmallIntegers and then does the comparison and jump directly branching on the condition codes. Consequently loops in VsualWorks are much faster. Also, the object representation is convoluted, compact classes being OK for reducing space overhead but bad at creating overhead and complexity, so much so that Cog as yet lacks machine code primitives for instance creation and at:put:.
So I hope that soon we'll upgrade the code generator and the object representation and will see another significant jump in compute performance to bring us up to VisualWorks levels. I hope that we'll also start working on inlining and get the fastest Smalltalk VM ever. We have a really exciting opportunity here with Exupery and Igor's Native Boost to do inlining in a Klein-like way, i.e. having SMalltalk code do inlining and code optimization. The only concern here is portability; keeping an intermediate bytecode might be wise. But we'll see. I'm also going to be working on the FFI, in part with my GSoC student, but also in Teleplace where I have threaded/non-blocking/overlapped calls woking in prototype form, but as yet lack proper calbacks.
So that speculation aside please do prepare reproducible cases of crashes or differences in behaviour between the current VM and Cog (I've just remembered that another difference is that Cog will produce Float infinity for 1.0/0.0 instead of failing). Crashes need to be fixed. Some semantic issues may need to change (for example I think the floating-point behaviour is better, does this need a flag to control as in VisualWorks's case, etc). But Cog being available is only the beginning, and now we can all be involved.
cheers Eliot
On 6/20/2010 2:23 PM, Lukas Renggli wrote:
Thank you Eliot.
This is wonderful, it feels like I just got a new laptop :-)
I noticed some problems in the continuation tests of Seaside (WAContinuationTest, WAFlowPlatformTest and WAPartialContinuationTest):
"Computation has been terminated" in MethodContext>>cannotReturn:Is this a known problem? Or is this maybe specific to Pharo on Cog?
It's a Cog bug. GeneratorTest dies with the same symptoms in 4.1.
Cheers, - Andreas
On 20 June 2010 22:53, stephane ducassestephane.ducasse@gmail.com wrote:
This is really an excellent news. I open a lot of new futures! Thanks teleplace, andreas and all the people that helped.
Stef PS: you already answer my questions about platform were the jit cannot work so this is great.
On Jun 20, 2010, at 10:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate ma
chine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt:& Float>>basicAt:put: that undo the reversal and an
swer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c& platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM.
That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with:& Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold:& SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality.
VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src the tree for the Cog generated sources including all plugins stacksrc/vm the directory containing the Stack VM source (plugins can be taken from above) platforms the usual svn platform tree but including Cog specific changes such as the heartbeat processors the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC& MIPS simulator, Skeye. image the Cog-prepared Squeak 4.1 VMMaker image scripts some svn scripts to revert unchanged plugins that haven't really changed cygwinbuild the win32 build directory winbuild the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin macbuild the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better unixbuild the build directory for linuxBuilding Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT): All contributions from Teleplace in this release are Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Eliot Miranda June 2010
Not much to say other than: Hooray Eliot!
And thanks to everyone who played a part in convincing the decision-makers at Teleplace that releasing Cog is a win for everybody.
Cheers, Josh
On Jun 20, 2010, at 1:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src the tree for the Cog generated sources including all plugins stacksrc/vm the directory containing the Stack VM source (plugins can be taken from above) platforms the usual svn platform tree but including Cog specific changes such as the heartbeat processors the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image the Cog-prepared Squeak 4.1 VMMaker image scripts some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild the win32 build directory winbuild the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin macbuild the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better unixbuild the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT): All contributions from Teleplace in this release are Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Eliot Miranda June 2010
Folks -
I've prepared a version of Squeak 4.1 for those of you who are not into recompiling VMs yourself. You can download it from:
http://squeakvm.org/win32/experimental/CogSqueak4.1.zip
The package contains a freshly compiled Cog VM for Windows and an updated Squeak4.1 image. Some things to note:
* Once you save the image with Cog, you can only run it with Cog. So load your benchmarks into the image *before* you launch it with Cog (i.e., to ensure you're comparing apples with apples you should use the same image)
* There are some changes that are required in the image. Most importantly, some LargeInt primitives need to be removed: #(= bitAnd: bitOr: bitShift: bitXor: ~=) do:[:sel| LargePositiveInteger removeSelector: sel. ].
This will be necessary for any images you want to run with Cog. There are also some other changes but they are not critical (i.e., don't crash the VM).
Enjoy, - Andreas
Just for the heck of it:
Squeak = Squeak-4.0.3.2202-linux_i386 on Ubuntu 10.4 CogVM = wine and win32 CogVM on Ubuntu 10.4 same image, same system
[Smalltalk browseAllCallsOn: #do:] timeToRun.
Squeak: 1984 CogVM: 877
[Morph methodsDo:[:meth| meth decompileString]] timeToRun.
Squeak: 1206 CogVM: 580
Examples of I/O heavy stuff:
[Morph compileAll] timeToRun.
Squeak: 3289 CogVM: 3076
[saveMorphs := World submorphs. World removeAllMorphs."heh, heh" time := [1 to: 10 do: [:i | Browser fullOnClass: SystemDictionary selector: #macroBenchmarks]. World submorphs do: [:m | m delete. self currentWorld doOneCycle]. ] timeToRun ] ensure:[World addAllMorphs: saveMorphs].
Squeak: 6586 CogVM: 5743
Alex
PS: Running all tests with the win32 CogVM using wine will produce a fatal vm crash at some point
On 06/21/2010 10:49 AM, Alexander Lazarević wrote:
Just for the heck of it:
Squeak = Squeak-4.0.3.2202-linux_i386 on Ubuntu 10.4 CogVM = wine and win32 CogVM on Ubuntu 10.4 same image, same system
[Smalltalk browseAllCallsOn: #do:] timeToRun.
Squeak: 1984 CogVM: 877
[SNIP]
Interesting, you don't seem to get as good numbers as Andreas did? Do you guys have different CPUs too?
regards, Göran
With "same image, same system" I was just referring to my setup (old notebook).
2010/6/21 Göran Krampe goran@krampe.se
On 06/21/2010 10:49 AM, Alexander Lazarević wrote:
Just for the heck of it:
Squeak = Squeak-4.0.3.2202-linux_i386 on Ubuntu 10.4 CogVM = wine and win32 CogVM on Ubuntu 10.4 same image, same system
[Smalltalk browseAllCallsOn: #do:] timeToRun.
Squeak: 1984 CogVM: 877
[SNIP]
Interesting, you don't seem to get as good numbers as Andreas did? Do you guys have different CPUs too?
regards, Göran
On 6/21/2010 1:49 AM, Alexander Lazarević wrote:
Just for the heck of it:
Squeak = Squeak-4.0.3.2202-linux_i386 on Ubuntu 10.4 CogVM = wine and win32 CogVM on Ubuntu 10.4 same image, same system
[Smalltalk browseAllCallsOn: #do:] timeToRun.
Squeak: 1984 CogVM: 877
That's ... odd. Perhaps some Wine thingie? We get *excellent* performance improvements on our RHEL servers in fact more so than on the client since the client is so much more I/O bound with graphics etc.
PS: Running all tests with the win32 CogVM using wine will produce a fatal vm crash at some point
Yup. TestObjectsAsMethods will die. I've just posted a fix for the trunk.
Cheers, - Andreas
On Sun, 20 Jun 2010, Andreas Raab wrote:
Folks -
I've prepared a version of Squeak 4.1 for those of you who are not into recompiling VMs yourself. You can download it from:
http://squeakvm.org/win32/experimental/CogSqueak4.1.zip
The package contains a freshly compiled Cog VM for Windows and an updated Squeak4.1 image. Some things to note:
- Once you save the image with Cog, you can only run it with Cog. So load
your benchmarks into the image *before* you launch it with Cog (i.e., to ensure you're comparing apples with apples you should use the same image)
- There are some changes that are required in the image. Most importantly,
some LargeInt primitives need to be removed: #(= bitAnd: bitOr: bitShift: bitXor: ~=) do:[:sel| LargePositiveInteger removeSelector: sel. ].
This will be necessary for any images you want to run with Cog. There are also some other changes but they are not critical (i.e., don't crash the VM).
Thanks. I tried some basic things with this image and crashed the VM a few times. For example updating from trunk crashes while the image is recompiling classes. An updated trunk image gives much better results. A few things are different or were not adopted to the VM: - Juan's BitBlt fixes seem to be missing - primitive 71 has an overflow bug (probably the same older Squeak VMs had). Allocating an array with 1073741824 elements gives an empty array, with 1073741825 elements results in an array with one slot. - TestObjectsAsMethods crashes the VM - Some VM parameters (Smalltalk vmParameters) are not integers but nil. This causes problems with MessageTally.
And some good news: evaluating [Morph methodDict valuesDo: 1] works as it should (http://bugs.squeak.org/view.php?id=7453 ).
Levente
Enjoy,
- Andreas
Wonderful news.
On 2010-06-20, at 1:11 PM, Eliot Miranda wrote:
The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64.
Now before anyone asks, it's very doubtful you will see Cogit on the iOS series of operating systems (iphone/ipad). I have had detailed discussions with the Apple Security team since their goal is to prevent user level code from doing dynamic code generation.
mmap for example won't return a page of memory that is executable.
Let's say the probability of getting Apple to change their minds on this is zero.
However I'll look into the StackInterpreter for the Macintosh 5.x VM and the iOS flavour, mind if anyone wants to do that chore early then they should ping me.
-- =========================================================================== John M. McIntosh johnmci@smalltalkconsulting.com Twitter: squeaker68882 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
For the binary-challenged, I am sure some kind soul will post compiled versions somewhere...!
(I ALWAYS struggle with build.bat, missing files, environment variables, and the like...)
Take care,
Rob
On Sun, Jun 20, 2010 at 5:37 PM, John M McIntosh < johnmci@smalltalkconsulting.com> wrote:
Wonderful news.
On 2010-06-20, at 1:11 PM, Eliot Miranda wrote:
The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64.
Now before anyone asks, it's very doubtful you will see Cogit on the iOS series of operating systems (iphone/ipad). I have had detailed discussions with the Apple Security team since their goal is to prevent user level code from doing dynamic code generation.
mmap for example won't return a page of memory that is executable.
Let's say the probability of getting Apple to change their minds on this is zero.
However I'll look into the StackInterpreter for the Macintosh 5.x VM and the iOS flavour, mind if anyone wants to do that chore early then they should ping me.
--
John M. McIntosh johnmci@smalltalkconsulting.com Twitter: squeaker68882 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
On 6/20/2010 2:42 PM, Rob Rothwell wrote:
For the binary-challenged, I am sure some kind soul will post compiled versions somewhere...!
For Windows, get yours here:
http://squeakvm.org/win32/experimental/CogSqueak4.1.zip
Cheers, - Andreas
(I ALWAYS struggle with build.bat, missing files, environment variables, and the like...)
Take care,
Rob
On Sun, Jun 20, 2010 at 5:37 PM, John M McIntosh <johnmci@smalltalkconsulting.com mailto:johnmci@smalltalkconsulting.com> wrote:
Wonderful news. On 2010-06-20, at 1:11 PM, Eliot Miranda wrote:The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64.Now before anyone asks, it's very doubtful you will see Cogit on the iOS series of operating systems (iphone/ipad). I have had detailed discussions with the Apple Security team since their goal is to prevent user level code from doing dynamic code generation. mmap for example won't return a page of memory that is executable. Let's say the probability of getting Apple to change their minds on this is zero. However I'll look into the StackInterpreter for the Macintosh 5.x VM and the iOS flavour, mind if anyone wants to do that chore early then they should ping me. -- =========================================================================== John M. McIntosh <johnmci@smalltalkconsulting.com <mailto:johnmci@smalltalkconsulting.com>> Twitter: squeaker68882 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
Wonderful !
A naive question: are there now specific coding guidelines for getting the best out of the JIT, or can we go and code as usual and expect all methods to run much faster automatically ?
Stef
On 6/20/2010 3:11 PM, Stéphane Rollandin wrote:
A naive question: are there now specific coding guidelines for getting the best out of the JIT, or can we go and code as usual and expect all methods to run much faster automatically ?
The latter. You should expect a 2-3x performance improvement in pretty much any kind of code (more towards 2x when running primitive and I/O bound stuff; more torwards 3x when running "pure" Smalltalk code).
Examples of non-I/O bound stuff:
[Smalltalk browseAllCallsOn: #do:] timeToRun.
Squeak: 779 CogVM: 258
[Morph methodsDo:[:meth| meth decompileString]] timeToRun.
Squeak: 537 CogVM: 166
Examples of I/O heavy stuff:
[Morph compileAll] timeToRun.
Squeak: 1510 CogVM: 766
[saveMorphs := World submorphs. World removeAllMorphs."heh, heh" time := [1 to: 10 do: [:i | Browser fullOnClass: SystemDictionary selector: #macroBenchmarks]. World submorphs do: [:m | m delete. self currentWorld doOneCycle]. ] timeToRun ] ensure:[World addAllMorphs: saveMorphs].
Squeak: 2633 CogVM: 1445
As usual for benchmarks YMMV slightly depending on what you're doing but I'd be surprised if you wouldn't get a 2-3x performance boost regardless of what you're doing.
Cheers, - Andreas
Andreas Raab a écrit :
The latter. You should expect a 2-3x performance improvement in pretty much any kind of code (more towards 2x when running primitive and I/O bound stuff; more torwards 3x when running "pure" Smalltalk code).
I tested it with a DrGeoII programmed interactive sketch. The instantiation time of a recursive morph canvas (about 320 morphs) was boosted by a factor of ~300%:
[Carre new] timeToRun
CogVM: 750 SqueakVM: 2200
I seem to have an issue in the new image with the method Point>>onLineFrom:to:within:
Alway return false in some circumstance. Need to find more.
Hilaire
...and Thanks a lot to share it.
o 0 o 0 o 0 o 0 o 0 o 0 |o | | o| |o | | o| |o | | o| | o | | o | | o | | o | | o | | o | |0 | |O | |0 | |O | |0 | |O | | 0| | 0| | 0| | 0| | 0| | 0| |O | |o | |O | |o | |O | |o | \ / \ / \ / \ / \ / \ / | | | | | | | | | | | | | | | | | | | | | | | | --- --- --- --- --- ---
Hilaire
Hilaire Fernandes a écrit :
Andreas Raab a écrit :
The latter. You should expect a 2-3x performance improvement in pretty much any kind of code (more towards 2x when running primitive and I/O bound stuff; more torwards 3x when running "pure" Smalltalk code).
I tested it with a DrGeoII programmed interactive sketch. The instantiation time of a recursive morph canvas (about 320 morphs) was boosted by a factor of ~300%:
[Carre new] timeToRun
CogVM: 750 SqueakVM: 2200
I seem to have an issue in the new image with the method Point>>onLineFrom:to:within:
Alway return false in some circumstance. Need to find more.
Hilaire
2010/6/20 Stéphane Rollandin lecteur@zogotounga.net
Wonderful !
A naive question: are there now specific coding guidelines for getting the best out of the JIT, or can we go and code as usual and expect all methods to run much faster automatically ?
Since Cog is a work in progress, and since future performance work should address performance needs of current code I would not want to recommend any changes in style. Cog is intended to make Squeak code run faster, and hopefully it'll get better at doing so.
best Eliot
Stef
On Sun, Jun 20, 2010 at 01:11:38PM -0700, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
Congratulations Eliot! And many thanks to those who supported your work and had the wisdom and foresight to make it publicly available.
Dave
Congratulations!
And is it possible to run a Croquet image on it, which is based on Squeak 3.8? What is needed for that? Will closure bootstrap from 2008 ( http://www.mirandabanda.org/files/Cog/Closures0811/Bootstrap/ClosureBootstra...) be enough?
Best regards, Nikolay
On Mon, Jun 21, 2010 at 12:11 AM, Eliot Miranda eliot.miranda@gmail.comwrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at
http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz
http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src
the tree for the Cog generated sources including all plugins
stacksrc/vm
the directory containing the Stack VM source (plugins can be taken from above)
platforms
the usual svn platform tree but including Cog specific changes such as the heartbeat
processors
the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image
the Cog-prepared Squeak 4.1 VMMaker image
scripts
some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild
the win32 build directory
winbuild
the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin
macbuild
the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better
unixbuild
the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status:
The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT):
All contributions from Teleplace in this release are
Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Eliot Miranda
June 2010
On 06/20/2010 10:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source
Great news, thanks Eliot for your work!
Paolo
Yay, I did not think this would happen anymore! Great Work and many thanks!
On Mon, Jun 21, 2010 at 11:41 AM, Paolo Bonzini bonzini@gnu.org wrote:
On 06/20/2010 10:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source
Great news, thanks Eliot for your work!
Paolo
On Sun, 20 Jun 2010, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the
This is fantastic, thanks.
<snip>
attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
I think it would be better to use an adaptive policy later. Something like: all methods will be inlined if they are evaluated enough times. Say a method with 10 literals will be inlined if it's evaluated 100 times. A method with 100 literals will need 10000 runs, etc. (note: i just made up the numbers).
Levente
Eliot Miranda wrote on Sun, 20 Jun 2010 13:11:38 -0700
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
Congratulations and thanks to Eliot and all involved!
One interesting use for this would be improving the performance of Etoys on the old OLPC XO-1 machines currently in use by over one million children around the world. The "few SSE2 instructions" mentioned in http://wiki.laptop.org/go/Geode_instruction_set might be a problem and loading projects into an image with a different format would certainly be a problem (though Andreas has suggested a way to deal with that). If these obstacles can be overcome, however, it would avoid splitting the OLPC community into early adopters and owners of shiny new XO-1.5, XO-1.75 and XO-3 devices.
-- Jecel
Hi Eliot,
Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
...
This is wonderful news! Thank you, Andreas, and all the people at Teleplace who made this possible!
I tried to run Cuis on the Windows VM Andreas did, and I'm having trouble. I did as follows:
1) Start Cuis 2.4 with the Closure VM 2) Install the attached changeset (made after your post and the tweaks 3) Exit saving the image 4) Start it with the Cog VM
When starting, it does an invalid memory access, and terminates without any error message or log. I guess I'd need to setup a VM building and debugging environment, etc, and learn quite a bit to fix this myself. I guess it would take you minutes to spot this, compared with the days I'd need to spend... I'd very much appreciate your help.
Thank you.
Cheers, Juan Vuletich
On 6/21/2010 11:29 AM, Juan Vuletich wrote:
When starting, it does an invalid memory access, and terminates without any error message or log. I guess I'd need to setup a VM building and debugging environment, etc, and learn quite a bit to fix this myself. I guess it would take you minutes to spot this, compared with the days I'd need to spend... I'd very much appreciate your help.
I've seen that before :-) Cog requires LargeNegativeInteger to be compact at 5 (previously PseudoContext). After installing and running the attached code in addition to the other changes you're good to go.
Enjoy! - Andreas
Hi Andreas,
Andreas Raab wrote:
On 6/21/2010 11:29 AM, Juan Vuletich wrote:
When starting, it does an invalid memory access, and terminates without any error message or log. I guess I'd need to setup a VM building and debugging environment, etc, and learn quite a bit to fix this myself. I guess it would take you minutes to spot this, compared with the days I'd need to spend... I'd very much appreciate your help.
I've seen that before :-) Cog requires LargeNegativeInteger to be compact at 5 (previously PseudoContext). After installing and running the attached code in addition to the other changes you're good to go.
Enjoy!
- Andreas
Yes. I yesterday downloaded XCode and built the Mac VM, only to find that it throws a clear error (LargeNegativeInteger is not compact at 5, can't continue) to the console. I told this to Eliot, but forgot to say it in the lists. I apologize. Anyway, for some reason, the win vm you posted, instead of giving the error and exiting cleanly, it does an invalid access and is terminated. Maybe you want to check that.
BTW, most console messages (i.e. stdout) will be missed in these days of graphical shells. An OS dialog would be better.
Thank Eliot, you and Teleplace for this great gift! This is a major milestone in the history of Squeak.
Cheers, Juan Vuletich
Excellence! Many thanks to everyone at Teleplace who made this possible, and special thanks to Eliot Miranda: I believe that your creation will be a great and lasting asset to this community. Thanks for putting up with all of our incessant inquiry:)
I think it's especially cool to have an open source VM of this class written in Slang. I know that I personally am fascinated with e.g. inline caching, and I'm sure I'm not alone. A fast VM, and one that is well situated to become a reference implementation, is about the greatest gift a guy like me could hope for, and it's not even Christmas.
I look forward to learning everything that I can from Cog!
"It's like they just gave you a new horse." --attrib. Dan Ingalls
On Jun 20, 2010, at 1:11 PM, Eliot Miranda eliot.miranda@gmail.com wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src the tree for the Cog generated sources including all plugins stacksrc/vm the directory containing the Stack VM source (plugins can be taken from above) platforms the usual svn platform tree but including Cog specific changes such as the heartbeat processors the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image the Cog-prepared Squeak 4.1 VMMaker image scripts some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild the win32 build directory winbuild the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin macbuild the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better unixbuild the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status: The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT): All contributions from Teleplace in this release are Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Eliot Miranda June 2010
Oh my gosh, I have been thinking about this moment for years, and your note took me by surprise. This is incredible! I will try it asap.
Eliot, congratulations! You, Teleplaces and Andreas have my sincere gratitude, thank you.
Thank you! Chris
On Sun, Jun 20, 2010 at 3:11 PM, Eliot Miranda eliot.miranda@gmail.com wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
This release contains two VMs. The Stack VM, is a cross-platform interpreter that uses context-to-stack mapping to achieve modest performance gains. The Cog VM is a just-in-time compiler that currently supports only x86 that builds upon the Stack VM to achieve substantial performance improvements. The release is in the form of a Monticello package containing the VMMaker source and a tarball containing the platform sources, the generated sources and a Squeak 4.1 image containing the VMMaker sources. Download both at
http://ftp.squeak.org/Cog/VMMaker-oscog.11.mcz
http://ftp.squeak.org/Cog/OpenSourceCog.tar.gz
Cog VMs:
The Cog VMs are Squeak/Croquet VMs that run closure Squeak/Croquet/Pharo/Cuis images. The VMs support existing plugin source but will require plugins to be recompiled as the VM_PROXY_MAJOR plugin api has been extended.
This release contains two distinct VMs, the StackInterpreter and the Cogit. The StackInterpreter is a fully-portable plug-in replacement for the current closure Squeak VMs and images. The Stack VM uses context-to-stack mapping and a somewhat improved garbage collector to achieve modest but useful performance gains in the 10% to 15% range. The StackInterpreter is intended to supersede the Squeak VM on platforms where the Cogit cannot be used. The Cogit extends the StackInterpreter with a just-in-time compiler that uses aggressive inline caching techniques to deliver substantial performance gains in the 3x to 15x range, depending on benchmark. The Cogit currently supports only x86 and the floating-point primitives and parts of the platform support code depend on SSE2. I hope members of the community will attempt to port it, e.g. to ARM, PowerPC and x86-64. The Cogit (excuse the pun) is so named because it is both an interpreter and a JIT, choosing not to generate machine code for large methods, interpreting them instead, the default policy being not to JIT methods with more than 60 literals.
The Cog VM requires a few minor image changes all in image/NecessaryImageChangesForCogToWork.1.cs. The JIT's machine-code SmallInteger primitives insist on a SmallInteger receiver so the primitives in LargePositiveInteger = ~= bitAnd: bitOr: butShift: and bitXor: cannot be used and these methods must be deleted. The Cogit inlines the address of the Character instance table, Smalltalk specialObjectsArray at: 25, into the machine-code at: primitive for faster ByteString>>at: and so the table cannot be rebuilt in SmalltalkImage>>recreateSpecialObjectsArray. The new version preserves the existing table. Both VMs maintain floats in platform order to ease implementation of machine code floating-point primitives, and hence internally are in little-endian order instead of big-endian in current Squeak images. While the VMs convert float order automatically on load they do require special accessing primitives Float>>basicAt: & Float>>basicAt:put: that undo the reversal and answer Float contents in big-endian order so that e.g. Float>>hash is unchanged. The methods assume these primitives can fail, allowing the code to be used on current Squeak VMs.
The image/VMMaker-Squeak4.1.image is a Squeak 4.1 image, runnable with the current Squeak VMs, that contains these changes, and can hence also be run with a Cog VM. But beware, once an image has been saved on Cog it cannot be run by an existing Squeak VM, because existing VMs cannot undo the Float order change.
Platform Subsystem:
Most of the platform subsystem is unchanged but there are some important changes that need description. The biggest change is the heartbeat and the clock in platforms/unix/vm/sqUnixHeartbeat.c and platforms/win32/vm/sqWin32Heartbeat.c. The Cog VMs avoid the slow and variable interruptCheckCounter, folding the event check into the stack overflow check on frame build. The heartbeat, typically 500Hz or 1KHz, changes the stackLimit to a value that will always fail. On the next frame building send the VM will enter stack overflow handling that, as a side effect, will also check for events. This is more efficient than the update of interruptCheckCounter and much more regular. If one is running code that executes long-running primitives (e.g. large integer arithmetic) the counter approach will result in too low an interrupt check frequency, and conversely if one is running normal code the interrupt check frequency can be very high.
The heartbeat also maintains a 64-bit microsecond clock, UTC microseconds from 1901, from which the backward-compatible millisecond and second clocks are derived. Primitives exist to answer UTC microseconds and local microseconds. Updating the clock in the heartbeat results in a 1 or 2 millisecond resolution but avoids the cost of accessing the OS time on every prim tie which we've found important for performance at Teleplace. The 64-bit microsecond clocks provide a unified time basis and eliminate wrapping (for the next 54,000 years at least). I hope community images will move to these clocks. It's worked well in VisualWorks.
Another significant change is in the external semaphore table support code. This is now lock-free at the cost of having to specify a maximum number of external semaphores at start-up (default 256). The support code for the lock-free data structures are processor-specific and is currently implemented only for x86 and gcc-compatible compilers; see platforms/Cross/vm/{sqAtomicOps.h,sqMemoryFence.h}.
There is also improved crash reporting code that prints a primitive log and a C backtrace in addition to the Smalltalk backtrace. See platforms/Mac OS/vm/sqMacMain.c, platforms/unix/vm/sqUnixMain.c, platforms/win32/vm/sqWin32Intel.c & platforms/win32/vm/sqWin32Backtrace.c.
Finally there is support for the QVMProfiler, a pc-sampling profiler for profiling at the VM level. See platforms/unix/vm/sqUnixVMProfile.c and platforms/win32/vm/sqWin32VMProfile.c. The profiler itself is in the VMMaker image described below in Qwaq-VMProfiling.
There are also changes to do with Teleplace-specific extensions to the HostWindowPlugin but these are not essential to Cog.
VMMaker and Slang:
The image/VMMaker-Squeak4.1.image Squeak 4.1 image contains the complete Cog VMMaker with necessary support code for simulation. This image was used to generate the sources in the src and stacksrc directories.
Cog's VMMaker is substantially revised and extended from the current VMMaker. It supports multiple classes, not just Interpreter and superclasses, because both context-to-stack mapping and the Cogit are too complex to write monolithically. Classes can specify ancilliaryClasses and ancilliaryStructClasses, such as CoInterpreterStackPage, CogMethod and CogAbstractInstruction. The Monticello package version is included in the header of all generated files and constitutes the version stamp for generated code. Code is generated in sorted order so that minor changes in the Smalltalk source produce correspondingly minor changes in the generated code. The gnuification step is built-in to VMMaker. No effort has been made to maintain 64-bit compatibility. Apologies, this was unaffordable.
The VMMaker generates a single source tree used by all platforms. Instead of deciding at generation time whether to use the Interpreter struct the generated code depends on the SQ_USE_GLOBAL_STRUCT define which can be overridden in platform makefiles. All plugins live in src/plugins and platform makefiles along with plugins.int and plugins.ext files in the build subdirectories decide which plugins are built as external or internal. The VM Generation Workspace from Workspace.text workspace contains dots to generate the sources. We no longer use the VMMakerTool since there should be nothing platform-specific in the generated sources (if we add ports to other ISAs all their source can be included and selected as required by the platform makefiles).
Since the Cogit generates x86 machine code simulation is much more complex. There is a support plugin, platforms/Cross/plugins/BochsIA32Plugin that depends on a large simulation of the x86 family implemented in C++ (see processors/IA32/bochs) and on Alien. I use the simulator frequently (but note that I haven't had time to build a working version for Squeak 4.1). I have tested Cog simulation in this image, running on the image/VMMaker-Squeak4.1.image itself. The VM Simulation Workspace in the VMMaker image contains an example doit that starts the simulator. Be patient, even on a fast machine unhibernating the Squeak display background image takes nearly a minute. Native fonts do not (yet) simulate correctly, but the system runs. But note that I have only attempted to build and run the simulator on Mac OS X. I expect Bochs can be built on linux and win32 but I have not tried. By the way, I've not described how to run the Bochs simulator on the current Squeak VM. That's because the plugin depends on the heartbeat to break out of simulation occasionally via a new interpreterProxy entry point setInterruptCheckChain. As this isn't supported by the current Squeak VMs the plugin would require modification. So to simulate first build either of the Cog VMs and then run the simulation with it.
There are a number of unpublished changes to the base other than those in NecessaryImageChangesForCogToWork.1.cs. This is partly laziness on my part, partly avoiding publishing things in advance of Cog. These changes are better motivated once Cog is in use. There are changes to the "translated primitives" (see implementors of translatedPrimitives) which replace messages with method tags for generation directives. The Cog VMMaker uses Object>>perform:with:with:with:with: & Object>>perform:with:with:with:with:with: during simulation, and Collection>>#fold: & SquenceableCollection>>#copyUpThrough: during generation. Object>>inline: and Object var:declareC:, which are mispackaged in Kernel in Squeak 4.1 are obsolete (method tags being used instead) and have been removed. I have changed Integer>>hex and Integer>>hex8 back to their original semantics as of 3.8. Backward compatibility is important and one can easily add new selectors if one wants different functionality. VMMaker was here first ;)
Tarball:
The top-level directories in the tarball are
src
the tree for the Cog generated sources including all plugins
stacksrc/vm
the directory containing the Stack VM source (plugins can be taken from above)
platforms
the usual svn platform tree but including Cog specific changes such as the heartbeat
processors
the tree containing simulation support code, i.e. the bochs C++ x86 simulation library, along with a potential ARM, PowerPC & MIPS simulator, Skeye.
image
the Cog-prepared Squeak 4.1 VMMaker image
scripts
some svn scripts to revert unchanged plugins that haven't really changed
cygwinbuild
the win32 build directory
winbuild
the old win32 build directory for minnow gcc 2.95. Not entirely obsolete as the cygwin build as yet fails to generate a functional FFIPlugin
macbuild
the CoreVM.xcodeproj and support build projects for Mac OS X 10.5 or better
unixbuild
the build directory for linux
Building Cog:
Each build directory above contains a HowToBuild file that describes building in more detail. The build directories only contain Cogit makefiles. f you want to build a Stack VM you're on your own but this is very close to the existing Squeak VM build.
Status:
The Cogit VM has been our sole VM at Teleplace for nearly a year. We do occasionally find bugs and there are almost certainly areas of functionality that we have not touched (for example I know that co-routining does not yet work). If you find a bug please try and create a reproducible test case and let me know. I can't promise to take a look or fix it but I am motivated to do so and will try my best as time allows. Better still if you find and fix bugs be sure to let me know.
License (MIT):
All contributions from Teleplace in this release are
Copyright (c) 2010 Teleplace, Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
Eliot Miranda
June 2010
Eliot, Andreas, Teleplace people, many thanks for this inspiring present.
Bye Enrico
On Sun, Jun 20, 2010 at 22:11, Eliot Miranda eliot.miranda@gmail.comwrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas.
[...]
Eliot Miranda
June 2010
Yes: thank you Eliot, Andreas, and Teleplace.
And with this awesome gift, there's an obligation: now we must go forth and build compelling applications on top of our spanking new engine!
frank
On 2010/06/22 09:49, Enrico Spinielli wrote:
Eliot, Andreas, Teleplace people, many thanks for this inspiring present.
Bye Enrico
On Sun, Jun 20, 2010 at 22:11, Eliot Miranda <eliot.miranda@gmail.com mailto:eliot.miranda@gmail.com> wrote:
Hi All, it gives me great pleasure to announce that the Teleplace Cog VMs are now available. Huge thanks to all at Teleplace who have given me the opportunity to build Cog and release it as open source, been willing guinea pigs braving its bugs, and providing indispensable participation in getting Cog to its current state. Huge thanks are also due to the original Back To The Future team whose VMMaker Cog extends to write the VM, and to Peter Deutsch from whom I've taken many ideas. [...] Eliot Miranda June 2010-- Enrico Spinielli "Do Androids dream of electric sheep?"— Philip K. Dick "Hear and forget; see and remember;do and understand."—Mitchel Resnick
Hello.
Cog performance is incredible. My application improved 3 times speedup. And I now does not need special caching logic in my program.
But I found very strange behavior in xml dom parsing of big text with many russian text (by XML-Parser XMLDOMParser class).
russionXml := String streamContents: [:s | s nextPutAll: '<root>'. 1000 timesRepeat: [ s nextPutAll: '<item>'. s nextPutAll: 'фывапролд'. s nextPutAll: '</item>']. s nextPutAll: '</root>' ].
[XMLDOMParser parseDocumentFrom: russionXml] timeToRun .
In pharo 1.1 I have
567 ms with old VM. 6673 ms with Cog VM.
But all other stuff that I tested work faster with Cog (at 3-4 times faster).
2010/6/22 Denis Kudriashov dionisiydk@gmail.com:
Hello.
Cog performance is incredible. My application improved 3 times speedup. And I now does not need special caching logic in my program.
But I found very strange behavior in xml dom parsing of big text with many russian text (by XML-Parser XMLDOMParser class).
russionXml := String streamContents: [:s | s nextPutAll: '<root>'. 1000 timesRepeat: [ s nextPutAll: '<item>'. s nextPutAll: 'фывапролд'. s nextPutAll: '</item>']. s nextPutAll: '</root>' ].
[XMLDOMParser parseDocumentFrom: russionXml] timeToRun .
In pharo 1.1 I have
567 ms with old VM. 6673 ms with Cog VM.
But all other stuff that I tested work faster with Cog (at 3-4 times faster).
Looks like the code using different paths. I suspect that in one case, some operations are done primitively, while in another one - interpreted.
It's strange. I loaded last version of XMLParser and all work very well (at 3 times faster)
2010/6/25 Igor Stasenko siguctua@gmail.com
2010/6/22 Denis Kudriashov dionisiydk@gmail.com:
Hello.
Cog performance is incredible. My application improved 3 times speedup.
And
I now does not need special caching logic in my program.
But I found very strange behavior in xml dom parsing of big text with
many
russian text (by XML-Parser XMLDOMParser class).
russionXml := String streamContents: [:s | s nextPutAll: '<root>'. 1000 timesRepeat: [ s nextPutAll: '<item>'. s nextPutAll: 'фывапролд'. s nextPutAll: '</item>']. s nextPutAll: '</root>' ].
[XMLDOMParser parseDocumentFrom: russionXml] timeToRun .
In pharo 1.1 I have
567 ms with old VM. 6673 ms with Cog VM.
But all other stuff that I tested work faster with Cog (at 3-4 times faster).
Looks like the code using different paths. I suspect that in one case, some operations are done primitively, while in another one - interpreted.
-- Best regards, Igor Stasenko AKA sig.
On Wed, 23 Jun 2010, Denis Kudriashov wrote:
Hello.
Cog performance is incredible. My application improved 3 times speedup. And I now does not need special caching logic in my program.
But I found very strange behavior in xml dom parsing of big text with many russian text (by XML-Parser XMLDOMParser class).
russionXml := String streamContents: [:s | s nextPutAll: '<root>'. 1000 timesRepeat: [ s nextPutAll: '<item>'. s nextPutAll: '?????????'. s nextPutAll: '</item>']. s nextPutAll: '</root>' ].
[XMLDOMParser parseDocumentFrom: russionXml] timeToRun .
I thought it's time to make use of the profiler, so I tried the same tests in a Squeak trunk image (4.2alpha-10280). To reduce the noise I ran the test 5 times:
russionXml := String streamContents: [:s | s nextPutAll: '<root>'. 1000 timesRepeat: [ s nextPutAll: '<item>'. s nextPutAll: '.........'. s nextPutAll: '</item>']. s nextPutAll: '</root>' ]. ((1 to: 5) collect: [ :run | [ XMLDOMParser parseDocumentFrom: russionXml readStream ] timeToRun ]) average asFloat
My results are: SqueakVM: 73.4 CogVM: 17.6
So CogVM is more than 4x faster than SqueakVM for this test.
Levente
In pharo 1.1 I have
567 ms with old VM. 6673 ms with Cog VM.
But all other stuff that I tested work faster with Cog (at 3-4 times faster).
Morning all, I've pushed a number of changes into the iOS platform tree to enable you to build a Macintosh Cocoa V5 Cog VM. Well at least one that runs a few million byte codes before crashing. This also requires changes to the Cog branch, but that's part of the re-integration process.
I have also built it as a Stack VM for the iPhone, that runs many more million bytecodes before tossing walkbacks on an unaltered image. Just a bit of image tinkering I think is needed there, plus a change to let complex events flow up out of the VM into the image, but again part of the re-integration process.
On 2010-06-20, at 1:11 PM, Eliot Miranda wrote:
Hi All,
it gives me great pleasure to announce that the Teleplace Cog VMs are now available. ... Eliot Miranda June 2010
-- =========================================================================== John M. McIntosh johnmci@smalltalkconsulting.com Twitter: squeaker68882 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
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