Samuel K. Gutierrez
Los Alamos National Laboratory
On Jun 9, 2010, at 9:58 AM, Sylvain Jeaugey wrote:
> As stated at the conf call, I did some performance testing on a 32
> cores node.
> So, here is graph showing 500 timings of an allreduce operation
> (repeated 15,000 times for good timing) with sysv, mmap on /dev/shm
> and mmap on /tmp.
> What is shows :
> - sysv has the better performance ;
> - having the mmap file in /dev/shm is very close to sysv. We only
> have +0.1 us for a complete allreduce operation, but it seems
> stable. The noise is identical to sysv (must be OS noise) ;
> - having the mmap file in /tmp (ext3) decreases performance (+0.4 us
> compared to /dev/shm) and seems prone to some "other" noise.
> Warning : the graph does not start at 0.
> On Tue, 27 Apr 2010, Samuel K. Gutierrez wrote:
>> With Jeff and Ralph's help, I have completed a System V shared
>> memory component for Open MPI. I have conducted some preliminary
>> tests on our systems, but would like to get test results from a
>> broader audience.
>> As it stands, mmap is the defaul, but System V shared memory can be
>> activated using: -mca mpi_common_sm sysv
>> Input is greatly appreciated!
>> Samuel K. Gutierrez
>> Los Alamos National Laboratory
>> devel mailing list
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