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Subject: [OMPI devel] processor affinity -- OpenMPI/batch system integration
From: Rayson Ho (rayrayson_at_[hidden])
Date: 2008-01-09 15:59:35


Hello,

I'm from the Sun Grid Engine (SGE) project (
http://gridengine.sunsource.net ). I am working on processor affinity
support for SGE.

In 2005, we had some discussions on the SGE mailing list with Jeff on
this topic. As quad-core processors are available from AMD and Intel,
and higher core count per socket is coming soon, I would like to see
what we can do to come up with a simple interface for the SGE 6.2
release, which will be available in Q2 this year (or at least into an
"update" release of SGE6.2 if we couldn't get the changes in on time).

The discussions we had before:
http://gridengine.sunsource.net/servlets/BrowseList?list=dev&by=thread&from=7081
http://gridengine.sunsource.net/servlets/BrowseList?list=dev&by=thread&from=4803

I looked at the SGE code, the simplest we can do is to set an
environment variable to tell the task group the processor mask of the
node before we start each task group. Is it good enough for OpenMPI??

After reading the OpenMPI code, I believe what we need to do is that
in ompi/runtime/ompi_mpi_init.c , we need to add an else case:

 if (ompi_mpi_paffinity_alone) {
   ...
 }
 else
 {
   // get processor affinity information from batch system via the env var
   ...
 }

Thanks,
Rayson