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Subject: Re: [OMPI users] Mapping ranks to hosts (from MPI error messages)
From: Sasso, John (GE Power & Water, Non-GE) (John1.Sasso_at_[hidden])
Date: 2014-03-28 09:47:06

Thanks again! I tried --display-devel-map and I think it provides a bit too much info for our needs. However, it is nice to know.

BTW, some interesting behavior in using "--report-bindings --bind-to-core" vs "--display-map".

* If I use "--report-bindings --bind-to-core" but the MPI tasks on a host fail to start up, then nothing is reported. For example, I had a problem where a job started across 4 hosts but the hosts could not communicate with one another via TCP/IP.

* If I use "--display-map" then the mapping is shown, even in the failure case I mentioned in the last bullet.

* What is nice about "--report-bindings --bind-to-core" over "--display-map" is that it will report the binding of each rank to CPU, whereas the latter will show you what ranks are running on a given host. For our needs, this may be sufficient, tho it would be nice to have the CPU bindings shown as well

* If using "--report-bindings --bind-to-core" with OpenMPI 1.4.1 then the bindings on just the head node are shown. In 1.6.1, full bindings across all hosts are shown. (I'd have to read release notes on this...)


-----Original Message-----
From: users [mailto:users-bounces_at_[hidden]] On Behalf Of Ralph Castain
Sent: Thursday, March 27, 2014 7:01 PM
To: Open MPI Users
Subject: Re: [OMPI users] Mapping ranks to hosts (from MPI error messages)'s Jeff's fault!

Fwiw you can get even more detailed mapping info with --display-devel-map

Sent from my iPhone

> On Mar 27, 2014, at 2:58 PM, "Jeff Squyres (jsquyres)" <jsquyres_at_[hidden]> wrote:
>> On Mar 27, 2014, at 4:06 PM, "Sasso, John (GE Power & Water, Non-GE)" <John1.Sasso_at_[hidden]> wrote:
>> Yes, I noticed that I could not find --display-map in any of the man pages. Intentional?
> Oops; nope. I'll ask Ralph to add it...
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
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> users mailing list
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