FWIW, if you looking for “MPI tasks” instead of OS processes, FG-MPI, which is a derivative of MPICH has done 100 million MPI tasks. http://www.mpich.org/2013/01/15/over-100-million-processes-with-mpich/ They had to make some changes to MPICH, which they are in the process of contributing back. —- Pavan On Oct 31, 2013, at 3:18 PM, Jeff Hammond <[email protected]> wrote:

Yes, we can :-) I've run 64 ppn on 48 racks of Mira, which is 3145728 MPI threads. But this is not the best one can do...

From http://www.cs.rpi.edu/~chrisc/COURSES/PARALLEL/SPRING-2013/papers/sequoia-ro...:

"The benchmark has 251 million PHOLD logical processes and was executed in several congurations up to a peak of 7.86 million MPI tasks running on 1,966,080 cores."

You'll need to get on to Tianhe-1 if you want to run on more _hardware_ threads that that.

Jeff

On Thu, Oct 31, 2013 at 1:59 PM, Bob Ilgner <[email protected]> wrote:

...

Hi Pavan,

With reference to your MPI on a million processors article, what is the largest number of threads that you have encountered on a system.

I have run 500 000 MPI threads on an IBM system. Can any of you guys out there top that ?

Regards, bob

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