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Subject: Re: [OMPI devel] trunk hangs since r19010
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2008-07-28 12:22:01

On Jul 28, 2008, at 11:05 AM, Ralph Castain wrote:

>> only openib works for me too,
>> but Glebs said to me once that it's illigal and I always need to
>> use self btl.
> Don't know - could be true. But if that is true, then we should
> check to see if that condition is met and error out - with an
> appropriate message - if so. Otherwise, how is a user supposed to
> know this condition?

This used to be true, but I think we changed it a while ago (Pasha: do
you remember?) because Mellanox HCAs are capable of send-to-self
(process) and there were no code changes necessary to enable it. So
it allowed a slightly simpler command line. This was quite a while
ago, IIRC.

All current iWARP adapters do not allow loopback communication at all
(i.e., communication to either the same proc or other procs on the
same host), so we added the following test in openib's add_procs:

         if (IBV_TRANSPORT_IWARP == openib_btl->device->ib_dev-
>transport_type &&
             0 != (ompi_proc->proc_flags && OMPI_PROC_FLAG_LOCAL)) {

(meaning: skip this proc if it's on the same host; let btl self handle
it, etc.)

Jeff Squyres
Cisco Systems