Let's talk about this in Dublin. I can probably help with the m4
magic, but I need to understand exactly what needs to be done first.
On Aug 16, 2008, at 11:51 AM, Terry Dontje wrote:
George Bosilca wrote:
The intent of the memcpy framework is to allow a selection between
several memcpy at runtime. Of course, there will be a preselection
at compile time, but all versions that can compile on a given
architecture will be benchmarked at runtime and the best one will
be selected. There is a file with several versions of memcpy for
x86 (32 and 64) somewhere around (I should have one if interested),
that can be used as a starting point.
Ok, I guess I need to look at this code. I wonder if there may be
cases for Sun's machines in which this benchmark could end up
picking the wrong memcpy?
The only thing we need is a volunteer to build the m4 magic.
Figuring out what we can compile if kind of tricky, as some of the
functions are in assembly, some others in C, and some others a
mixture (the MMX headers).
Isn't the atomic code very similar? If I get to this point before
anyone else I probably will volunteer.
--td
george.
On Aug 16, 2008, at 3:19 PM, Terry Dontje wrote:
Hi Tim,
Thanks for bringing the below up and asking for a redirection to
the devel list. I think looking/using the MCA memcpy framework
would be a good thing to do and maybe we can work on this together
once I get out from under some commitments. However, some of the
challenges that originally scared me away from looking at the
memcpy MCA is whether we really want all the OMPI memcpy's to be
replaced or just specific ones. Also, I was concerned on trying
to figure out which version of memcpy I should be using. I
believe currently things are done such that you get one version
based on which system you compile on. For Sun there may be
several different SPARC platforms that would need to use different
memcpy code but we would like to just ship one set of bits.
Not saying the above not doable under the memcpy MCA framework
just that it somewhat scared me away from thinking about it at
first glance.
--td
Date: Fri, 15 Aug 2008 12:08:18 -0400 From: "Tim Mattox" <timat...@open-mpi.org
> Subject: Re: [OMPI users] SM btl slows down bandwidth? To:
"Open MPI Users" <us...@open-mpi.org> Message-ID: <ea86ce220808150908t62818a21k32c49b9b6f07...@mail.gmail.com
> Content-Type: text/plain; charset=ISO-8859-1 Hi Terry (and
others), I have previously explored this some on Linux/X86-64 and
concluded that Open MPI needs to supply it's own memcpy routine
to get good sm performance, since the memcpy supplied by glibc is
not even close to optimal. We have an unused MCA framework
already set up to supply an opal_memcpy. AFAIK, George and Brian
did the original work to set up that framework. It has been on my
to-do list for awhile to start implementing opal_memcpy
components for the architectures I have access to, and to modify
OMPI to actually use opal_memcpy where ti makes sense. Terry, I
presume what you suggest could be dealt with similarly when we
are running/building on SPARC. Any followup discussion on this
should probably happen on the developer mailing list. On Thu, Aug
14, 2008 at 12:19 PM, Terry Dontje <terry.don...@sun.com> wrote:
> Interestingly enough on the SPARC platform the Solaris
memcpy's actually use
> non-temporal stores for copies >= 64KB. By default some of
the mca
> parameters to the sm BTL stop at 32KB. I've done
experimentations of
> bumping the sm segment sizes to above 64K and seen incredible
speedup on our
> M9000 platforms. I am looking for some nice way to integrate
a memcpy that
> lowers this boundary to 32KB or lower into Open MPI.
> I have not looked into whether Solaris x86/x64 memcpy's use
the non-temporal
> stores or not.
>
> --td
>>
>> Message: 1
>> Date: Thu, 14 Aug 2008 09:28:59 -0400
>> From: Jeff Squyres <jsquy...@cisco.com>
>> Subject: Re: [OMPI users] SM btl slows down bandwidth?
>> To: rbbr...@sandia.gov, Open MPI Users <us...@open-mpi.org>
>> Message-ID: <562557eb-857c-4ca8-97ad-f294c7fed...@cisco.com>
>> Content-Type: text/plain; charset=US-ASCII; format=flowed;
delsp=yes
>>
>> At this time, we are not using non-temporal stores for
shared memory
>> operations.
>>
>>
>> On Aug 13, 2008, at 11:46 AM, Ron Brightwell wrote:
>>
>>
>>>>
>>>> >> [...]
>>>> >>
>>>> >> MPICH2 manages to get about 5GB/s in shared memory
performance on the
>>>> >> Xeon 5420 system.
>>>>
>>>
>>> >
>>> > Does the sm btl use a memcpy with non-temporal stores
like MPICH2?
>>> > This can be a big win for bandwidth benchmarks that
don't actually
>>> > touch their receive buffers at all...
>>> >
>>> > -Ron
>>> >
>>> >
>>> > _______________________________________________
>>> > users mailing list
>>> > us...@open-mpi.org
>>> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>>>
>>
>>
>> -- Jeff Squyres Cisco Systems
>
> _______________________________________________
> users mailing list
> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users
>
-- Tim Mattox, Ph.D. - http://homepage.mac.com/tmattox/ tmat...@gmail.com
|| timat...@open-mpi.org I'm a bright... http://www.the-brights.net/
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