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Subject: Re: [OMPI users] Running OpenMPI on SGI Altix with 4096 cores : very poor performance
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-01-07 09:50:10


Can you run with np=8?

On Jan 7, 2011, at 9:49 AM, Gilbert Grosdidier wrote:

> Hi Jeff,
>
> Thanks for taking care of this.
>
> Here is what I got on a worker node:
>
> > mpirun --mca mpi_paffinity_alone 1 /opt/software/SGI/hwloc/1.1rc6r3028/bin/hwloc-bind --get
> 0x00000001
>
> Is this what is expected, please ? Or should I try yet another command ?
>
> Thanks, Regards, Gilbert.
>
>
>
> Le 7 janv. 11 à 15:35, Jeff Squyres a écrit :
>
>> On Jan 6, 2011, at 11:23 PM, Gilbert Grosdidier wrote:
>>
>>>> lstopo
>>> Machine (35GB)
>>> NUMANode L#0 (P#0 18GB) + Socket L#0 + L3 L#0 (8192KB)
>>> L2 L#0 (256KB) + L1 L#0 (32KB) + Core L#0
>>> PU L#0 (P#0)
>>> PU L#1 (P#8)
>>> L2 L#1 (256KB) + L1 L#1 (32KB) + Core L#1
>>> PU L#2 (P#1)
>>> PU L#3 (P#9)
>>> L2 L#2 (256KB) + L1 L#2 (32KB) + Core L#2
>>> PU L#4 (P#2)
>>> PU L#5 (P#10)
>>> L2 L#3 (256KB) + L1 L#3 (32KB) + Core L#3
>>> PU L#6 (P#3)
>>> PU L#7 (P#11)
>> [snip]
>>
>> Well, this might disprove my theory. :-\ The OS indexing is not contiguous on the hyperthreads, so I might be wrong about what happened here. Try this:
>>
>> mpirun --mca mpi_paffinity_alone 1 hwloc-bind --get
>>
>> You can even run that on just one node; let's see what you get. This will tell us what each process is *actually* bound to. hwloc-bind --get will report a bitmask of the P#'s from above. So if we see 001, 010, 011, ...etc, then my theory of OMPI binding 1 proc per hyperthread (vs. 1 proc per core) is incorrect.
>>
>> --
>> Jeff Squyres
>> jsquyres_at_[hidden]
>> For corporate legal information go to:
>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>
>
> --
> *---------------------------------------------------------------------*
> Gilbert Grosdidier Gilbert.Grosdidier_at_[hidden]
> LAL / IN2P3 / CNRS Phone : +33 1 6446 8909
> Faculté des Sciences, Bat. 200 Fax : +33 1 6446 8546
> B.P. 34, F-91898 Orsay Cedex (FRANCE)
> *---------------------------------------------------------------------*
>
>
>
>
>

-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/