[Vm-dev] Re: Different bytecode set per process

[timfelgentreff]

Hi Ben,

We once experimented with STM to run Squeak Processes on multiple cores
without any restrictions to the bytecodes. Due to the STM foundations, any
conflicts are resolved automatically (with quite a bit of performance impact
as more and more conflicts occur). But for algorithms that do not share data
structures (except an output of some kind) we did actually see quite a bit
of speedup when scaling over multiple cores - without any changes to the
image.

Now, if we had such a bytecode set restriction that could be attached to a
process, this experiment could become very interesting again.

Best,
Tim


Ben Coman wrote
> On Wed, Jun 8, 2016 at 6:07 AM,  <

> commits at .squeak

> > wrote:
>>
>> Eliot Miranda uploaded a new version of VMMaker to project VM Maker:
>> http://source.squeak.org/VMMaker/VMMaker.oscog-eem.1884.mcz
>>
>> Fix multiple bytecode set selection in the Spur 64-bit VM, which must use
>> signedIntFromLong64 to test for a negative header.
> 
> 
> Just a strange spark of an idea thats been floating in my head for a
> while regarding use of multiple CPU cores (it doesn't need a response
> - it just helps quiet my thoughts to share them...)
> 
> The main problem with multiple native threads is concurrent
> modification objectmemory, plus most of the Image is not designed for
> such parallel execution,
> but...
> 
> What if you could have a bytecode set that had all the bytecodes which
> modify objectmemory stripped out, so that only stack operations were
> permitted. And if a forked Smalltalk Process could be restricted to
> that bytecodeset (swapping the bytecode set when the Process is woken
> in #transferTo:), then you kindof enforce a functional style of
> programming for that Process that could not interfere with
> objectmemory.
> 
> This might be suitable for some forms of intensive data processing
> that crunch a lot of data down to a small result.  Maybe it would be
> difficult for such a forked Process to deal with the main UI Process
> changing objectmemory underfeet.
> 
> cheers -ben





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