gmp-discuss Digest, Vol 44, Issue 12

Wed Apr 18 19:50:07 CEST 2007

Hi.
I am from EPFL where we are trying to implement GMP-ECM on the PS3. There is
already a version of Linux which has been installed. Our idea was to run one
curve per processor. I would be interested in looking at the some code that
has already been adapted to Cell processor or the PowerPC architecture which
uses the GMP library.
Thanks.

On 18/04/07, gmp-discuss-request at swox.com <gmp-discuss-request at swox.com>
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> Today's Topics:
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>    1. GMP on the Cell processor (Torbjorn Granlund)
>    2. Re: GMP on the Cell processor (Michael Abshoff)
>    3. Re: GMP on the Cell processor (Paul Leyland)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: 17 Apr 2007 21:15:26 +0200
> From: Torbjorn Granlund <tg at swox.com>
> Subject: GMP on the Cell processor
> To: gmp-discuss at swox.com
> Message-ID: <86bqhm6cdt.fsf at king.swox.se>
> Content-Type: text/plain; charset=iso-8859-1
>
>   Has anyone on this list thought of porting GMP to the Cell processor?
>   Would anyone be interested in using GMP if it was on the Cell?
>
> I think it would be tricky to make a port that would do justice to the
> Cell.  The parallelism in GMP is fine-grained, at least as long as the
> operands are not really huge.
>
> If you want to work on a GMP Cell port, please start by studying how
> to write a plain basecase multiplication (mpn_mul_basecase) for the
> processor.  The divide-and-conquer structure of most algorithms in GMP
> will make use of of mpn_mul_basecase.
>
>   On a similar note, is there a version of GMP for the Altivec
>   which is this vector extension for some (but not all) PowerPC
>   CPU's ?
>
> GMP 4.2 makes use of Altivec when it is available.  (There are some
> flaws in configure that made the altivec recognition unreliable,
> though.)
>
> --
> Torbj?rn
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 17 Apr 2007 22:16:07 +0200 (CEST)
> From: "Michael Abshoff"
>         <Michael.Abshoff at fsmath.mathematik.uni-dortmund.de>
> Subject: Re: GMP on the Cell processor
> To: gmp-discuss at swox.com
> Message-ID:
>         <
> 63903.80.144.208.181.1176840967.squirrel at fsmath.mathematik.uni-dortmund.de
> >
>
> Content-Type: text/plain;charset=iso-8859-1
>
> Torbjorn Granlund wrote:
> >   On a similar note, is there a version of GMP for the Altivec
> >   which is this vector extension for some (but not all) PowerPC
> >   CPU's ?
> >
> > GMP 4.2 makes use of Altivec when it is available.  (There are some
> > flaws in configure that made the altivec recognition unreliable,
> > though.)
> >
>
> The Cell is a hyprid of a dual Core PowerCore (in order) and up to 8 SPEs
> (also in order). The great performance for numerical applications comes
> from the fact that you can achieve up to 200 GFlops *single* precision and
> about 1/14 of that for *double* precision with hand tuned code that uses
> all the SPEs in parallel. The Power Core just feeds the SPEs. The SPEs
> also supposedly provide integer operations and because each SPE has 128
> 128bit registers there is certainly potential. Cell blades are rather
> costly (dual Cell from IBM at around ~15K$), but you can get a PCI-Express
> card with a single Cell for around 4K$. To play around there is also an
> emulator (free as in beer) and a toolchain based on gcc (free as in
> freedom ;) that lets you play around provided you have some decent
> hardware (1.5GHZ PPC, x86, x86-64, 1+G Ram). The emulator supposedly gives
> you something that is very close (~2%) to the physical CPU because it also
> takes into consideration DMA transfers, cache misses and all the other fun
> stuff.
>
> I am currently starting to play around with the emulator for some
> numerical  project group I am working with, but provided somebody does
> start to port I would certainly be willing to test & debug and maybe code
> a little. I will also have (limited) access to some real hardware in the
> future. Because I also do work on other open source projects I do not have
> whole lot of time to do so.
>
> If you own a PS3 you can install Linux and have access to 6 SPEs because
> the hypervisor of the PS3 only gives you access to those 6 while the 7th
> is reserved for hypervisor. But it is a relatively cheap way to get one's
> hands on some real Cell hardware.
>
> Hope that helps,
>
> Michael
>
> > --
> > Torbj?rn
> > _______________________________________________
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> > gmp-discuss at swox.com
> > https://gmplib.org/mailman/listinfo/gmp-discuss
> >
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: 17 Apr 2007 21:18:22 +0100
> From: Paul Leyland <paul at leyland.vispa.com>
> Subject: Re: GMP on the Cell processor
> To: Torbjorn Granlund <tg at swox.com>
> Cc: gmp-discuss at swox.com
> Message-ID: <1176841102.17051.26.camel at athlon>
> Content-Type: text/plain; charset="us-ascii"
>
> On Tue, 2007-04-17 at 20:15, Torbjorn Granlund wrote:
> >   Has anyone on this list thought of porting GMP to the Cell processor?
> >   Would anyone be interested in using GMP if it was on the Cell?
> >
> > I think it would be tricky to make a port that would do justice to the
> > Cell.  The parallelism in GMP is fine-grained, at least as long as the
> > operands are not really huge.
>
> I've been giving it some thought recently, but the pressure of Real Life
> (TM) and, especially, Real Work has been such that the thought hasn't
> got very far yet.
>
> Your (Torbjorn) analysis is accurate but not the whole story, IMO.
>
> My interest is primarily in integer factorization, several algorithms
> for which are trivially parallelizable and computationally demanding (as
> opposed to memory-intensive).  ECM is probably the best example but
> there are others, including some which are subroutines for other
> algorithms such as NFS.  Other algorithms are not entirely trivial to
> parallelize but the Chinese Remainder Theorem provides an obvious entry
> point into their parallelization.
>
> Running 7 copies of stage 1 of ECM suimultaneously, each with the same N
> but different curves, on the SPUs of a PS3 using their local memory is
> *very* attractive.   Their second stages, which are very memory-hungry,
> would then be farmed out either to the main PPC or to other more
> conventional machines.
>
> GMP for the SPU, a stripped down version if necessary to get it to fit
> in the limited memory, would be very welcome indeed.
>
>
> Paul
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