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More registers in modern day CPUs
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Date: 2007-12-04 (14:37)
From: Basile STARYNKEVITCH <basile@s...>
Subject: Re: [Caml-list] minithread (was OCaml on Sony PS3)
Christophe Raffalli wrote:
> I propose the following idea for OCaml on Cell PowerPC or multicore
> machine (this is just an idea,
> there ay be a lot of thing I did not see ... in other word there is
> probably a lot of work to do, but may be not too much):
> - Create two functions and one data type to start "mini-thread":

As David MENTRE explained, this is not very realistic.

However, (one of the) the CELL coprocessor -eg SPU) might be used to 
implemented Ocaml garbage collector.

A copying GC has to move quite a lot of data, and it could be possible 
that CELL's coprocessors could be useful for that (assuming that they 
access memory as quickly as the processor).

I don't know if Gallium has resources for that (I suppose not, except 
perhaps maybe for an internship?), and I have no idea if it is easily 
doable or nearly impossible (maybe the current SPU limitations -in 
particular code size- are too strong).

Anyway, it might not help that much performance on Cells systems (eg 
PS3) because the GC is probably at most eating less than half of the 
resources (Damien & Xavier told me recently that the GC is usually using 
less than 20% of CPU, the KnuthBendix test case on ocamlopt being 
unusual to eat about a third of the CPU time). The Ocaml GC is quite 
good (a big bravo to Damien Doligez & Xavier Leroy).

I still think that SPU on PS3 are only useful for games, or specialized 
(e.g. graphical) applications.

Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
8, rue de la Faiencerie, 92340 Bourg La Reine, France
*** opinions {are only mines, sont seulement les miennes} ***