Berkeley UPC on Cray XD1

From: Adam Leko (leko_at_hcs_dot_ufl_dot_edu)
Date: Sat Oct 07 2006 - 15:22:49 PDT

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    What's the best way to run Berkeley UPC on a Cray XD1?  I notice from 
    the GASNet conduit there is support for the MPI and SMP conduits.  I 
    think the built-in MPICH on the XD1 takes advantage of the RapidArray, 
    and it seems to have pretty good performance (advertised 1.7us latency, 
    and on a chassis I've seen even less in unscientific measurements).  The 
    MPI conduit currently has OK performance but has some anomolies which 
    might be due to the polling-based implementation interacting with the 
    specialized MPICH version.
    Are there any other options that better suit the XD1 hardware?  I'm not 
    sure if RapidArray is going to make it into any future Cray products, 
    but if so it seems worth supporting.  Our lab is interested because we 
    might be doing something with both UPC and reconfigurable computing, and 
    a platform with excellent RC and good UPC support is interesting.
    Some notes: The Cray website claims support for SHMEM, but it is
    provided via GPSHMEM and a BUPC -> SHMEM conduit -> GPSHMEM -> ARMCI
    solution seems kind of gross.  There's also a "Global Arrays" interface
    which looks like it is also layered above ARMCI.  However, either
    option seems better suited than the MPI conduit.
    (As a side note, anyone with an HCS lab account can access our XD1 at but let us know before you pound it with long jobs)
    -Adam Leko

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