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Subject: Re: [OMPI devel] [PATCH] openib: clean-up connect to allow for new cm's
From: Gleb Natapov (glebn_at_[hidden])
Date: 2007-12-12 08:41:17

On Wed, Dec 12, 2007 at 03:37:26PM +0200, Pavel Shamis (Pasha) wrote:
> Gleb Natapov wrote:
> > On Tue, Dec 11, 2007 at 08:16:07PM -0500, Jeff Squyres wrote:
> >
> >> Isn't there a better way somehow? Perhaps we should have "select"
> >> call *all* the functions and accept back a priority. The one with the
> >> highest priority then wins. This is quite similar to much of the
> >> other selection logic in OMPI.
> >>
> >> Sidenote: Keep in mind that there are some changes coming to select
> >> CPCs on a per-endpoint basis (I can't look up the trac ticket right
> >> now...). This makes things a little complicated -- do we need
> >> btl_openib_cpc_include and btl_openib_cpc_exclude MCA params to
> >> include/exclude CPCs (because you might need more than one CPC in a
> >> single job)? That wouldn't be hard to do.
> >>
> >> But then what to do about if someone sets to use some XRC QPs and
> >> selects to use OOB or RDMA CM? How do we catch this and print an
> >> error? It doesn't seem right to put the "if num_xrc_qps>0" check in
> >> every CPC. What happens if you try to make an XRC QP when not using
> >> xoob? Where is the error detected and what kind of error message do
> >> we print?
> >>
> >>
> > In my opinion "X" notation for QP specification should be removed. I
> > didn't want this to prevent XRC merging so I haven't raced this point.
> > It is enough to have two types of QPs "P" - SW credit management "S" -
> > HW credit management.
> How will you decide witch QP type to use ? (SRQ or XRC)
If both sides support XOOB and priority of XOOB is higher then all other CPC
then create XRC, otherwise use regular RC.