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Multi-threaded VM

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Michael van der Gulik-2

Multi-threaded VM

On 10/27/07, Rob Withers <[hidden email]> wrote:

----- Original Message -----
From: "Peter William Lount" <[hidden email]>

> You're plan sounds excellent. Thank you for taking up the task of making
> Squeak VM multi-threaded with native threads!
>
> If you need anything...

I don't want to make it sound like I can't use some help, especially if it's
offered.  I can't do this alone.  Forget it, especially with the day job.
No, I figure it to be a 2 year task, at least.  But I would rather build
something than talk about all the theory.  I fleshed out the phases I posted
earlier with what I thought were some more managable tasks.  I'd like to
point out that Phase 3, implementing the multithreaded vm, is entirely
independent of SqueakElib and would be useable by anyone wanting to do
multithreading.

Here's the new page, add what you like, help where you can, holler to talk
it over: http://wiki.squeak.org/squeak/6011

Hi Rob.

I think that many other people would be interested in this. I suggest making stage 3 here a separate project in its own right. If it is stable and works well, I could see it becoming the official Squeak VM. Also keep integration with Exupery in mind.

I also recommend starting this project by changing the behaviour of ProcessorScheduler to behave in the same way as the multi-threaded VM. Currently code can assume that a lower priority process won't run while a higher priority process is busy; this assumption would no longer exist in the multi-threaded VM. This would be a reasonably simple change and I believe this may pick up several concurrency issues in the image.

Gulik.

--
http://people.squeakfoundation.org/person/mikevdg
http://gulik.pbwiki.com/

Rob Withers

Re: Multi-threaded VM

Hey Gulik,

I think that's a great idea. I moved the appropriate section to a new wiki page. http://wiki.squeak.org/squeak/6012

Cheers,

Rob

----- Original Message -----

From: [hidden email]

I think that many other people would be interested in this. I suggest making stage 3 here a separate project in its own right. If it is stable and works well, I could see it becoming the official Squeak VM. Also keep integration with Exupery in mind.

I also recommend starting this project by changing the behaviour of ProcessorScheduler to behave in the same way as the multi-threaded VM. Currently code can assume that a lower priority process won't run while a higher priority process is busy; this assumption would no longer exist in the multi-threaded VM. This would be a reasonably simple change and I believe this may pick up several concurrency issues in the image.

Sebastian Sastre-2

RE: Multi-threaded VM

Hi Rob, all,

a concrete initiative after so much discussion. I'm happy to hear that. I think being conservative like the N interpreters model is a good desicion at this, not so mature in multicore-stage. It buys time for more long run ones.

All the best for the teams!

Sebastian Sastre

De: [hidden email] [mailto:[hidden email]] En nombre de Rob Withers
Enviado el: Viernes, 26 de Octubre de 2007 22:29
Para: The general-purpose Squeak developers list
Asunto: Re: Multi-threaded VM

Hey Gulik,

I think that's a great idea. I moved the appropriate section to a new wiki page. http://wiki.squeak.org/squeak/6012

Cheers,

Rob

----- Original Message -----

From: [hidden email]

I think that many other people would be interested in this. I suggest making stage 3 here a separate project in its own right. If it is stable and works well, I could see it becoming the official Squeak VM. Also keep integration with Exupery in mind.

I also recommend starting this project by changing the behaviour of ProcessorScheduler to behave in the same way as the multi-threaded VM. Currently code can assume that a lower priority process won't run while a higher priority process is busy; this assumption would no longer exist in the multi-threaded VM. This would be a reasonably simple change and I believe this may pick up several concurrency issues in the image.

Bryce Kampjes

Multi-threaded VM

In reply to this post by Michael van der Gulik-2

Michael van der Gulik writes:
> Hi Rob.
>
> I think that many other people would be interested in this. I suggest making
> stage 3 here a separate project in its own right. If it is stable and works
> well, I could see it becoming the official Squeak VM. Also keep integration
> with Exupery in mind.

So long as there are no object memory changes then Exupery should be
easy to port to it. The only thing to be aware of is Context objects
that are being executed are not accurately populated. This is not
a problem for a single threaded VM as it's impossible to reflect
on a context without exiting it to execute the primitive.

That said, I don't think it would be that hard to make the VM multi
threaded. It would probably require a GC rewrite but such a rewrite
could also make single threaded execution faster and allow for a
mostly background old space collector. I've thought about such a
rewrite when looking at some memory access sequences but it would be
after Exupery 3.0 in my list. Squeak's GC is a good fit for the
current interpreter but may start looking slow if execution was 10
times faster.

Bryce