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Subject: Re: [OMPI devel] OMPI OpenIB Credit Schema breaks Chelsio HW
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-03-10 11:03:27


On Mar 10, 2008, at 9:50 AM, Steve Wise wrote:

> (just thinking out loud here): The OMPi code could be designed to
> _not_
> assume recv's are posted until the CPC indicates they are ready. IE
> sort
> of asynchronous behavior. When the recvs are ready, the CPC could
> up-call the btl and then the credits could be updated. This sounds
> painful though :)

That's the way it works, but only for the initial credits. The CPC is
not involved beyond that.

So it's likely that you'll still have this problem after initial
wireup for OMPI PP QP's (except as I noted below, if we only allow
that chelsio rnic to only have one PP QP and it has to be qp 0).

> On the single-QP angle, Can I just run OMPI with only specifying 1 QP?
> Or will that require coding changes?

No coding changes required; just change the value of
mca_btl_openib_receive_queues.

-- 
Jeff Squyres
Cisco Systems