Hi Rob, Can we increase the number of open files on Mira to 1 million? Currently the number of open files is set to be 65536, and users can increase it manually to its hard limitation of 81920. Can we increase this hard limitation to 1 million for Mira for a one week test on MPI IO in Mira? Thanks. --------------- /etc/security/limits.conf--------------------------------- root soft nofile 65536 root hard nofile 81920 <-- Best, [email protected] From: Latham, Robert J. Date: 2017-04-19 22:35 To: [email protected] Subject: Re: [mpich-discuss] Installation on Blue Gene/Q On Wed, 2017-04-19 at 13:58 +0200, pramod kumbhar wrote:
Hi Rob,
Is this already installed/avaialble on MIRA? I would like to try this to check some mpi i/o hints.
Yes, there are several versions available: manual progress optimized: /projects/aurora_app/mpich3-ch4-ofi/install/gnu/bin auto progress optimized: /projects/aurora_app/mpich3-ch4-ofi/install-auto/gnu/bin manual progress debug: /projects/aurora_app/mpich3-ch4-ofi/install/gnu.debug/bin auto progress debug: /projects/aurora_app/mpich3-ch4-ofi/install-auto/gnu.debug/bin There are some performance considerations (both positive and negative) to consider: Current performance improvements versus [IBM's vendor-supplied MPICH]: 1.) Pt2pt latency - better than 2x speedup for small messages, large ones with few ranks-per-node less so due to detriment #2 listed below. 2.) RMA latency - exponentially better for small messages, then becomes gradually even for large messages in the case of put and get. Current performance detriments versus [IBM's vendor-supplied MPICH]: 1.) No optimized collectives -- all collectives are pt2pt algorithms in MPICH CH4. There is a plan to develop optimized collectives via OFI triggered operations but that work wouldn't begin until the April-May timeframe at the earliest. There is also a plan to make optimized pt2pt collectives available sooner. 2.) Only 1 rget injection fifo utilized per rank to pt2pt communication --- pami can utilize up all 11 to maximize internode bandwidth, you would mainly see this have an impact if you are running < 8 ranks per node and passing large messages. ==rob _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss