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MPI run-time at large scale

June 28, 2011 at 5:00 am PST

With the news that Open MPI is being used on the K supercomputer (i.e., the #1 machine on the June 2011 Top500 list), another colleague of mine, Ralph Castain — who focuses on the run-time system in Open MPI — pointed out that K has over 80,000 processors (over 640K cores!).  That’s ginormous.

He was musing to me that it would be fascinating to see some of K’s run-time data for what most people don’t consider too interesting / sexy: MPI job launch performance.

For example, another public use of Open MPI is on Los Alamos National Lab’s RoadRunner, which has 3,000+ nodes at 4 processes per node (remember RoadRunner?  It was #1 for a while, too).

It’s worth noting that Open MPI starts up full-scale jobs on RoadRunner — meaning that all processes complete MPI_INIT — in less than 1 minute.

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Open MPI powers 8 petaflops

June 25, 2011 at 6:20 pm PST

A huge congratulations goes goes out to the RIKEN Advanced Institute for Computational Science and Fujitsu teams who saw the K supercomputer achieve over 8 petaflops in the June 2011 Top500 list, published this past week.

8 petaflops absolutely demolishes the prior record of about 2.5 petaflops.  Well done!

A sharp-eyed user pointed out the fact that Open MPI was referenced in the “Programming on K Computer” Fujitsu slides (which is part of the overall SC10 Presentation Download Fujitsu site).  I pinged my Fujitsu colleague on the MPI Forum, Shinji Sumimoto, to ask for a few more details — does K actually use Open MPI with some customizations for their specialized network?  And did Open MPI power the 8 petaflop runs at an amazing 93% efficiency?

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