This is the wrong email list for such a question. Please contact ALCF support regarding Mira. Jeff On Thu, Apr 20, 2017 at 1:35 AM, [email protected] <[email protected]> wrote:

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. <[email protected]> *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

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-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss