mmap performance issue with 5.1B

From: Hegarty, John (John.Hegarty_at_pearson.com)
Date: 04/29/03

  • Next message: Murthy Hebbar: "DS20 system hangs" 
    Date: Tue, 29 Apr 2003 14:25:28 -0500
To: tru64-unix-managers@ornl.gov

    Hi managers,
     
    We've just upgraded from an alpha running 4.0F to an EV45 running 5.1B with
    the latest patch kit installed. The applications we run mmap a 400M file
    which they use for shared data structures. This mmap file is locked into
    memory with the mlockall routine. Now that we are running 5.1B we are having
    serious performance issues when under load and what I suspect is happening
    is that the system is writing the file back to disk approximately every 30
    seconds. Under 4.0F that was apparently done when the last program detached
    the mmap as near as we can determine. We have tried setting
    AdvfsSyncMmapPages = 0 and new_wire_method = 0 and neither has helped the
    situation, the system still puts all the programs into an uninterruptible
    sleep and we see large amounts of disk activity on the volume containing the
    mmap file every half minute or so. We also tried moving the mmap file to a
    UFS volume which helped somewhat but the performance is still not at all
    comparable to what it was under 4.0F. Any suggestions?
     
    Thanks in advance,
    John Hegarty

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