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Subject: Re: [OMPI devel] RFC: convert send to ssend
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-08-24 13:25:52

On Aug 24, 2009, at 11:35 AM, George Bosilca wrote:

> As a side note, a very similar effect can be obtained by decreasing
> the eager size of the BTLs to be equal to the size of the match
> header, which is about 24 bytes.

I disagree with this statement. ;-)

We currently don't export the BTL or PML header size, so you can't
possibly know what value to set the eager limit to. And even if we
did, as the conversation between you, me, and Brian from the last
Chicago Forum meeting proved, the exact definition of "eager_limit" is
a fairly nebulous thing.

My point is that this is a fairly trivial-to-implement feature. It
can even be done in a way that doesn't impact performance at all
(default to compile out). We all know that there are many MPI
correctness tools that are available, but it can be difficult to get
users to actually use them. If they can flip a switch a mpirun time
to turn on some semantic checking, that's a Good Thing.

Jeff Squyres