I would guess that for Open MPI v1.1, we will use more vmem than
MPT. Our strategy early on was get a huge buffer and never run out
of resources. Obviously, that's not a good long term plan ;). We've
scaled this down considerably in v1.2 (now in beta), where we by
default use about 16MB/process for shared memory, up to 512MB. THis
can be tuned down quite a bit -- we need about 128KB / process of
shared memory space to successfully run, and probably 4-8MB to run
with any efficiency.
Brian
On Jan 16, 2007, at 10:49 PM, <aaron.mcdono...@csiro.au>
<aaron.mcdono...@csiro.au> wrote:
I found that MPT uses a *lot* of vmem for buffering/mem mapping. We
schedule based on requested vmem, so this can be a problem. Do you
know
how vmem usage for buffering compares with OpenMPI?
Cheers,
Aaron
-----Original Message-----
From: users-boun...@open-mpi.org [mailto:users-bounces@open-
mpi.org] On
Behalf Of Brian W. Barrett
Sent: Wednesday, 17 January 2007 1:49 PM
To: Open MPI Users
Subject: Re: [OMPI users] openmpi on altix
On Jan 16, 2007, at 4:29 PM, Brock Palen wrote:
What is the state of openMPI on a sgi altix? How does it compare to
mpt. I assume for all operations OMPI will use the sm btl thus all
others (other than self) could be disabled. Is there any other
tweaks users use? Or is OMPI even recommend on at Altix?
We've run Open MPI on the Altix here at Los Alamos. For point-to-
point communication, we're slightly slower than MPT. But for
collectives, we're much slower. We just haven't done any work on
shared memory collectives, especially on platforms where the memory
hierarchies are as deep as they are on the Altix. That being said,
it should work and is a viable option if there's a feature of Open
MPI that a user needs that is not available in MPT.
Brian
--
Brian Barrett
Open MPI Team, CCS-1
Los Alamos National Laboratory
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