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Subject: Re: [OMPI devel] Heads up on new feature to 1.3.4
From: Eugene Loh (Eugene.Loh_at_[hidden])
Date: 2009-08-17 10:52:32


Jeff Squyres wrote:

> On Aug 16, 2009, at 11:02 PM, Ralph Castain wrote:
>
>> UNLESS you have a threaded application, in which case -any- binding
>> can be highly detrimental to performance.
>
> I'm not quite sure I understand this statement. Binding is not
> inherently contrary to multi-threaded applications.

I think the concern is that if a process binds to a particular core and
all threads inherit the same binding, then all threads will bind to the
same core, inhibiting multithreading speedups (at best).

If you bind to sockets rather than specific cores, even if multiple
threads inherit the same binding, the contention will be less.