Re: [OMPI devel] collective problems

[George Bosilca]

Decrease the latency is the main reason. If we delay the MPI completion, then we always have to call opal_progress at least once in order to allow the BTL to trigger the callback. In the current implementation, we never call opal_progress on small messages, unless there is some kind of resource starvation.

  Thanks,
    george.

On Nov 8, 2007, at 11:09 AM, Andrew Friedley wrote:

Brian Barrett wrote:

Personally, I'd rather just not mark MPI completion until a local

we came up with a way for back pressure from the BTL to say "it's not
on the wire yet".  This is more complicated than just not marking MPI
completion early, but why would we do something that helps real apps
at the expense of benchmarks?  That would just be silly!

completion callback from the BTL. But others don't like that idea, so

FWIW this issue is also very relevant for the UD BTL, especially with

send-side completion semantics).  I missed it, what was the reasoning
for not marking MPI completion until a callback from the BTL?

Andrew
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some new work I've done in the last week (currently having problems with

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