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Subject: Re: [OMPI devel] [PATCH] openib: clean-up connect to allow for new cm's
From: Pavel Shamis (Pasha) (pasha_at_[hidden])
Date: 2007-12-12 08:37:26

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)

> I think connection management should work like
> this: Each BTL knows what type of CPC it can use and it should share
> this info during modex stage. During connection establishment modex info
> is used to figure out the list of CPCs that both endpoints support and one
> with highest prio is selected.
ok for me.
> --
> Gleb.
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