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Subject: Re: [OMPI users] pinning processes by default
From: Albert Solernou (albert.solernou_at_[hidden])
Date: 2014-05-23 09:58:01


Hi,
thanks a lot for your quick answers, and I see my error, it is
"--bind-to none" instead of "--bind-to-none".

However, I need to be able to run "mpirun -np 2" without any binding
argument and get a "--bind-to none" behaviour. I don't know if I can
export an environment variable to do that, and I don't mind to
re-compile with some flag I missed or to alter the code.

Any suggestion?

Albert

On 23/05/14 14:32, Ralph Castain wrote:
> Note that the lama mapper described in those slides may not work as it hasn't been maintained in a while. However, you can use the map-by and bind-to options to do the same things.
>
> If you want to disable binding, you can do so by adding "--bind-to none" to the cmd line, or via the MCA param "hwloc_base_binding_policy=none"
>
> If you want to bind your process to multiple cores (say one per thread), then you can use "--map-by core:pe=N". Many hybrid users prefer to bind to a socket, with one process for each socket - that can be done with "--map-by socket --bind-to socket". This keeps all the threads in the same NUMA domain. If you aren't sure that each socket is its own NUMA domain, you can alternatively "--map-by numa --bind-to numa" - that'll keep you in your own NUMA domain regardless of whether that's at the socket level or elsewhere.
>
> I'm working on adding a full description of the mapping/binding system to our web site.
>
> HTH
> Ralph
>
> On May 23, 2014, at 6:22 AM, Brock Palen <brockp_at_[hidden]> wrote:
>
>> Albert,
>>
>> Actually doing affinity correctly for hybrid got easier in OpenMPI 1.7 and newer, In the past you had to make a lot of assumptions, stride by node etc,
>>
>> Now you can define a layout:
>>
>> http://blogs.cisco.com/performance/eurompi13-cisco-slides-open-mpi-process-affinity-user-interface/
>>
>> Brock Palen
>> www.umich.edu/~brockp
>> CAEN Advanced Computing
>> XSEDE Campus Champion
>> brockp_at_[hidden]
>> (734)936-1985
>>
>>
>>
>> On May 23, 2014, at 9:19 AM, Albert Solernou <albert.solernou_at_[hidden]> wrote:
>>
>>> Hi,
>>> after compiling and installing OpenMPI 1.8.1, I find that OpenMPI is pinning processes onto cores. Although this may be
>>> desirable on some cases, it is a complete disaster when runnning hybrid OpenMP-MPI applications. Therefore, I want to disable this behaviour, but don't know how.
>>>
>>> I configured OpenMPI with:
>>> ./configure \
>>> --prefix=$OPENMPI_HOME \
>>> --with-psm \
>>> --with-tm=/system/software/arcus/lib/PBS/11.3.0.121723 \
>>> --enable-mpirun-prefix-by-default \
>>> --enable-mpi-thread-multiple
>>>
>>> and:
>>> ompi_info | grep paffinity
>>> does not report anything. However,
>>> mpirun -np 2 --report-bindings ./wrk
>>> reports bindings:
>>> [login3:04574] MCW rank 1 bound to socket 0[core 1[hwt 0-1]]: [../BB/../../../../../..][../../../../../../../..]
>>> [login3:04574] MCW rank 0 bound to socket 0[core 0[hwt 0-1]]: [BB/../../../../../../..][../../../../../../../..]
>>> but they cannot be disabled as:
>>> mpirun -np 2 --bind-to-none ./wrk
>>> returns:
>>> mpirun: Error: unknown option "--bind-to-none"
>>>
>>> Any idea on what went wrong?
>>>
>>> Best,
>>> Albert
>>>
>>> --
>>> ---------------------------------
>>> Dr. Albert Solernou
>>> Research Associate
>>> Oxford Supercomputing Centre,
>>> University of Oxford
>>> Tel: +44 (0)1865 610631
>>> ---------------------------------
>>> _______________________________________________
>>> users mailing list
>>> users_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
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-- 
---------------------------------
   Dr. Albert Solernou
   Research Associate
   Oxford Supercomputing Centre,
   University of Oxford
   Tel: +44 (0)1865 610631
---------------------------------