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  1. #1
    Join Date
    Aug 2008
    Location
    Toronto, Canada
    Posts
    2,367

    Unanswered: "max locked memory" ulimit

    "ulimit -a" for a db2 instance on Linux RHEL:

    User Limits, 'ulimit -a'

    core file size (blocks, -c) 0
    data seg size (kbytes, -d) unlimited
    scheduling priority (-e) 0
    file size (blocks, -f) unlimited
    pending signals (-i) 141312
    max locked memory (kbytes, -l) 32
    max memory size (kbytes, -m) unlimited
    open files (-n) 1024
    pipe size (512 bytes, -p) 8
    POSIX message queues (bytes, -q) 819200
    real-time priority (-r) 0
    stack size (kbytes, -s) 10240
    cpu time (seconds, -t) unlimited
    max user processes (-u) 141312
    virtual memory (kbytes, -v) unlimited
    file locks (-x) unlimited


    On some systems, I see "max locked memory" set to some value (ie. 16, 32) and on some it's set to unlimited.


    From man pages:
    -l The maximum size that may be locked into memory


    From http://training.intersystems.com/tut...GCI_unixparms:

    "Locked-in Memory
    On Linux platforms if you configure Caché to lock the shared memory segment in memory to prevent paging, you must increase the maximum size that may be locked into memory (the memlock parameter). "


    Based on my understanding, "max locked memory" is the maximum amount of memory a process can pin. Does it mean that if a process makes a request to pin more memory that what's specified by this parameter, memory allocation will fail? Anyone knows?

  2. #2
    Join Date
    Apr 2010
    Posts
    10
    Not sure memory allocation will fail, if the process makes a request to pin more memory that what's specified by this parameter.


    But if its fail as an workaround you can set the "max locked memory" for a user to unlimited.

    > su
    > ulimit -l unlimited
    > exit
    > ulimit -a

    or you can also set by leave /etc/security/limits.conf empty

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