Re: upcrun + sockets

From: Paul H. Hargrove (PHHargrove_at_lbl_dot_gov)
Date: Tue Jun 09 2009 - 12:25:04 PDT

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      We do not have direct control of process/thread pinning via upcrun.  
    In particular the only placement-related arguments we pass to aprun are 
    -n and -N.  However, on the Cray XT one can launch Berkeley UPC 
    applications directly with aprun, for instance to use the -S and -d 
    options.  The only thing to keep in mind if one does so is that many of 
    the options to upcrun operate by setting environment variables.  So, if 
    you use any non-default options to upcrun you should run 'upcrun -show 
    <your args>' and look for lines beginning with "*** upcrun setting:", to 
    find the env vars that are being used (you can safely ignore UPC_NODES 
    and GASNET_SSH_SERVERS, which don't affect anything on the Cray XT).
      Let us know if you need more information.
    Gabriele Jost wrote:
    > Hello!
    > Does upcrun support placing threads/processing on different sockets of a multi-core node? Like, on a Cray XT5 (just as an example), I can specify "aprun -S 1" to ensure that 1 MPI process is placed on each socket. I know about "upcrun -c 2" to use only 2 cores, but I guess this does not mean 1 core on each socket.
    > Thanks in advance,
    > Gabriele
    Paul H. Hargrove                          PHHargrove_at_lbl_dot_gov
    Future Technologies Group                 Tel: +1-510-495-2352
    HPC Research Department                   Fax: +1-510-486-6900
    Lawrence Berkeley National Laboratory     

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