[Mpi-forum] MPI_Mprobe workaround

[Torsten Hoefler]

Jeff,

> Hmm, it seems I've stumbled upon a variant of Listing 1.1 in your paper :-)
Yes.

> I'm a big fan of buffer pools, so I am unfazed by the potential
> performance impact of sbrk().  If you need to malloc() so much memory
> that sbrk() is called, I suspect that the message transfer time is
> going to take longer than a system call.  
Keep in mind that you may (hopefully!) have multiple interfaces. If the
network bandwidth does not scale with the number of cores that one may
have all kinds of different issues.

The paper shows also that the benefit if Mprobe (using std malloc) can
be measured, even on yesterday's systems (eight cores if I remember
correctly).

> But I confess to being somewhat ignorant of the performance of slow,
> general purpose operating systems like Linux.
You forgot "widely available" and "portable" in this list ;-).

Torsten

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Torsten Hoefler         | Performance Modeling and Simulation Lead
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