[mvapich-discuss] pthreads and mvapich?

[Gil Bloch]

> -----Original Message-----
> From: mvapich-discuss-bounces at cse.ohio-state.edu
[mailto:mvapich-discuss-
> bounces at cse.ohio-state.edu] On Behalf Of Tim Hartley
> Sent: Monday, November 26, 2007 9:43 AM
> To: mvapich-discuss at cse.ohio-state.edu
> Subject: [mvapich-discuss] pthreads and mvapich?
> 
> Hi all,
> 
> I'm new to the list and am having a strange problem when running
> pthreads in an MPI process.  The MPI calls are made safely, i.e. only
> from the initial process.  The pthreads are just workers.  However, on
> a multicore system, the pthreads always get scheduled on the same
> core.  That is, multiple pthreads do not get scheduled on more than
> one core concurrently.  I'm mainly curious if anyone has run into this
> before.

It seems like the MVAPICH process affinity feature prevent your process
from using all cores in the node. Can you try using the following flag
to disable affinity?
VIADEV_USE_AFFINITY=0

- Gil

> 
> This is mvapich 0.9.9, gcc 4.1.1, AMD Athlon(tm) 64 X2 Dual Core
> Processor 4600+.  I can provide more information if necessary. I can
> provide small sample programs, and screenshots of top, too.
> 
> Sadly, I won't be able to recompile mvapich, because I can't find the
> infiniband driver on the system.
> 
> Thanks,
> Tim Hartley
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