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From: Heywood, Todd (heywood_at_[hidden])
Date: 2007-03-21 17:08:25


P.s. I should have said this this is a pretty course-grained application,
and netstat doesn't show much communication going on (except in stages).

On 3/21/07 4:21 PM, "Heywood, Todd" <heywood_at_[hidden]> wrote:

> I noticed that my OpenMPI processes are using larger amounts of system time
> than user time (via vmstat, top). I'm running on dual-core, dual-CPU
> Opterons, with 4 slots per node, where the program has the nodes to
> themselves. A closer look showed that they are constantly switching between
> run and sleep states with 4-8 page faults per second.
>
> Why would this be? It doesn't happen with 4 sequential jobs running on a
> node, where I get 99% user time, maybe 1% system time.
>
> The processes have plenty of memory. This behavior occurs whether I use
> processor/memory affinity or not (there is no oversubscription).
>
> Thanks,
>
> Todd
>
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