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Subject: Re: [OMPI devel] Ticket 1224: disable early completion in v1.2.x series
From: Shipman, Galen M. (gshipman_at_[hidden])
Date: 2008-03-03 12:48:40


Unfortunately this adds an "if" to the critical path.
You should at least use OPAL_UNLIKELY..

On Mar 3, 2008, at 12:28 PM, Jeff Squyres wrote:

> The topic of the "early completion" behavior in OB1 for IB
> optimizations has come up several times in the v1.2 series (it causes
> problems in some scenarios).
>
> - leave the default the way it is now (early completions enabled)
> - add an MCA parameter for disabling early completions
>
> I mention this now because I had a customer complain about it over the
> weekend. :-)
>
> Gleb and I propose the patch in https://svn.open-mpi.org/trac/ompi/
> ticket/1224
> for the v1.2 series. The new OB1 MCA parameter
> pml_ob1_use_early_completions defaults to 1 (preserving the same
> behavior as the rest of the v1.2 series), but it can be set to 0 if
> the early completions on IB are creating problems for specific
> applications.
>
> It would be good to get this functionality in a real release (e.g.,
> v1.2.6).
>
> Note that this MCA parameter is not necessary for the upcoming v1.3
> series because of changes in ob1 and the openib btl.
>
> --
> Jeff Squyres
> Cisco Systems
>
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