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Subject: Re: [OMPI users] openmpi credits for eager messages
From: Gleb Natapov (glebn_at_[hidden])
Date: 2008-02-04 15:17:01


On Mon, Feb 04, 2008 at 02:54:46PM -0500, Richard Treumann wrote:
> In my example, each sender task 1 to n-1 will have one rendezvous message
> to task 0 at a time. The MPI standard suggests descriptors be small enough
> and there be enough descriptor space for reasonable programs . The
> standard is clear that unreasonable programs can run out of space and fail.
> The standard does not try to quantify reasonableness.
You are right about your example, but I was not talking specifically about it.
Your example should work with Open MPI over IB/TCP because while rank 0 sleeps
without calling progress, transport layer flow control should throttle senders.
(SM doesn't have flow control that is why it fails.) What I was trying to say that
in MPI a process can't fully control its resource usage.

--
			Gleb.