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Subject: Re: [OMPI users] MPI jobs ending up in one node
From: Peter Teoh (htmldeveloper_at_[hidden])
Date: 2009-03-14 04:48:57 is in Intel MPI library. Thanks!!!

On Fri, Mar 13, 2009 at 9:47 PM, Ralph Castain <rhc_at_[hidden]> wrote:
> Hmmm...your comments don't sound like anything relating to Open MPI. Are you
> sure you are not using some other MPI?
> Our mpiexec isn't a script, for example, nor do we have anything named
> :-)
> On Mar 13, 2009, at 4:00 AM, Peter Teoh wrote:
>> I saw the following problem posed somewhere - can anyone shed some
>> light?   Thanks.
>> I have a cluster of 8-sock quad core systems running Redhat 5.2. It
>> seems that whenever I try to run multiple MPI jobs to a single node
>> all the jobs end up running on the same processors. For example, if I
>> were to submit 4 8-way jobs to a single box they all end up in CPUs 0
>> to 7, leaving 8 to 31 idle.
>> I then tried all sorts of I_MPI_PIN_PROCESSOR_LIST combinations but
>> short of explicitly listing out the processors at each run, they all
>> end up still hanging on to CPUs 0-7. Browsing through the mpiexec
>> script, I realise that it is doing a taskset on each run.
>> As my jobs are all submitted through a scheduler (PBS in this case) I
>> cannot possibly know at job submission time which CPUs are not used.
>> So is there a simple way to tell mpiexec to set the taskset affinity
>> correctly at each run so that it will choose only the idle processors?
>> Thanks.
>> --
>> Regards,
>> Peter Teoh
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
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Peter Teoh