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Subject: Re: [OMPI users] Pros and cons of --enable-heterogeneous
From: David Ronis (David.Ronis_at_[hidden])
Date: 2010-10-07 17:27:37

Ralph, thanks for the reply.

If I build with enable-heterogeneous and then decide to run on a
homogeneous set of nodes, does the additional "overhead" go away or
become completely negligible; i.e., if no conversion is necessary.


On Thu, 2010-10-07 at 15:17 -0600, Ralph Castain wrote:
> Hetero operations tend to lose a little performance due to the need to
> convert data, but otherwise there is no real negative. We don't do it
> by default solely because the majority of installations don't need to,
> and there is no reason to lose even a little performance if it isn't
> necessary.
> If you want an application to be able to span that mix, then you'll
> need to set that configure flag.
> On Thu, Oct 7, 2010 at 1:44 PM, David Ronis <David.Ronis_at_[hidden]>
> wrote:
> I have various boxes that run openmpi and I can't seem to use
> all of
> them at once because they have different CPU's (e.g.,
> pentiums, athlons
> (both 32 bit) vs Intel I7 (64 bit)). I'm about the build
> 1.4.3 and was
> wondering if I should add --enable-heterogenous to the
> configure flags.
> Any advice as to why or why not would be appreciated.
> David
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