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Subject: Re: [OMPI devel] sm BTL flow management
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-06-23 23:58:45

Not sure I can address that broader issue, but would you like us to
acid test your fix?

Be happy to put it through the wringer... :-)


On Jun 23, 2009, at 7:40 PM, Eugene Loh wrote:

> I have a fix for ticket 1944 working, but the broader problem is
> unpleasant. E.g., let's say we have zillions of uncountered Bcasts
> or something. Say, the root is repeatedly emitting sends, but never
> polling its in-coming FIFO. Return fragments will be accumulating,
> the FIFO will be congested, pending-send queues on peer processes
> will be growing, etc. The code now handles this (by growing the
> pending-send queues and eventually draining them, pre-1.3.2 we would
> also have handled this by growing the FIFO and using up the shared
> memory), but the whole thing is disturbing. E.g., queues might
> drain only when the root reaches MPI_Finalize. (Okay, unclear to me
> what sort of real application would have communications only from
> one process going out.)
> So, is this (one-way communications, e.g., repeated Bcasts)
> pathological and not worth worrying about. Or, are other solutions
> worth considering? E.g., I'd like to have a sending process run
> mca_btl_sm_component_progress occasionally, even if it is
> successfully completing its sends.
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