What about much coarser level threading? Was Re: Questions on Squeak's threading architecture

Tim Rowledge tim at sumeru.stanford.edu
Wed Aug 4 21:11:32 UTC 2004


Ed Boyce <edboyce at bu.edu> wrote:

>      I have a follow-up question if I may: What about parallelizing 
> things at a much coarser level?  Like within an SMP machine running a 
> SMP capable OS, load N copies of the whole Squeak VM (or perhaps a pared 
> down core of it), each into its own protected memory local to its very 
> own processor on which it runs as a process that is tied to that 
> processor, and then allow certain high-level userland objects to pass 
> messages to cousin objects running on the VMs of other Squeak images on 
> other processors through a piece of "globally" shared memory.  I say 
> "let certain objects" do this, because those objects would have to be 
> designed to play nice within their specially designed message sharing 
> space, and the host OS probably needs some kind of NUMA support (which 
> Linux does have).
I guess that would devolve to pretty much what HP did for DistributedST
-  use some sockets to communicate and away you go. Craig Latta has
also been doing some interesting inter-image coomunications for his
Squat system and indeed there are things like Nebraska that provide
another sort of inter-image messaging.

> 
>      So, does the Squeak VM use any system-absolute global variables 
> that would prevent one from running multiple instances of itself as 
> separate processor-bound processes on a SMP supercomputer?
I regularly run several instances of Squeak on my decidedly
non-supercomputer RISC OS machine so at least for that VM it is
possible; I know of no problems on other OSs to stop you doing
likewise. On suitable systems I'd iamgine you would get some advantage
of code sharing too. Cincom VisualWorks also provides some explicit
memory mapping/sharing for the image, work which was originally done
for Sequent (do they even exist anymore) to save memory space when
running hundreds of images at once.


tim
--
Tim Rowledge, tim at sumeru.stanford.edu, http://sumeru.stanford.edu/tim
A successful tool is used to do something undreamed of by its author.  - Johnson



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