Newsgroups: comp.parallel.mpi
From: Jen Mante <jrm51@columbia.edu>
Subject: ch_shmem on Origin/IRIX 6.4
Organization: NAS/NASA Ames Research Center
Date: Mon, 09 Mar 1998 11:32:25 -0800
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Message-ID: <350443C9.41C6@columbia.edu>

Hi,

I'm experiencing a few anomolies when using the shared memory
device on a 64 processor Origin with the shared memory device.

There's a case with a NAS parallel benchmark (BT) that works
just fine with 1,4, and 16 processors but just flakes out with 25.
This works fine with SGI's MPI.  I really don't think it's a
bug in the benchmark that is only showing up due to some timing
difference, so I was wondering if anyone had experienced a similar
problem with using a number of processors (say > 16).  (This
problem doesn't show up with the p4 device.)

Also, the shmem device doesn't want to let me run with more
than 32 processors.  Enabling >32 looks like a relatively easy 
change to make in the device, perhaps just redefining a constant? 
Has anyone done this?

Thanks,

--
Lou Zechtzer
lou@nas.nasa.gov