[mpich-discuss] Affinity with MPICH_ASYNC_PROGRESS

[Jeff Hammond]

My understanding, having looked at the code for this, is that no
thread binding is set.  The OS will hopefully do the right thing when
the cores are undersubscribed, but I see no thread affinity code in
the MPICH source for the comm threads.  MVAPICH has some additional
(i.e. non-MPICH) affinity code but I think it is mostly for
process-binding.

I have a modified version of MPICH that allows the user to set the
affinity of the comm threads explicitly.  I was interested in pinning
all of the comm threads to one core and letting them fight for time.
For example, on an 8-core node, I was hoping to get async progress on
7 processes by pinning 7 comm threads to the 8th core.

My patches for setting comm thread affinity are pretty simple.  I
assume you want me to share them?

Jeff

On Sat, Feb 23, 2013 at 6:23 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> Do the Hydra affinity settings apply to the internal comm thread created
> using MPICH_ASYNC_PROGRESS? Is there a way to set affinity for the comm
> threads so that they do not compete with application threads?
>
> http://wiki.mpich.org/mpich/index.php/Using_the_Hydra_Process_Manager#Process-core_Binding
>
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-- 
Jeff Hammond
Argonne Leadership Computing Facility
University of Chicago Computation Institute
jhammond at alcf.anl.gov / (630) 252-5381
http://www.linkedin.com/in/jeffhammond
https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond