PMON Consuming 50% CPU
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Thread: PMON Consuming 50% CPU

  1. #1
    Join Date
    Apr 2001
    Location
    London
    Posts
    725
    Oracle8.1.6
    SCO UX 7.1.1
    IGB Memmory
    2 Processors

    I have noticed PMON is consuming 50% CPU time, even when only a few users are connected.

    There are no trace files produced.

    Usually around 130 users logged on.

    Can anyone give me any queries/tuning tips to help establish what it is doing and why it is consuming so much CPU

    Thanks

    Suresh
    Once you have eliminated all of the impossible,
    whatever remains however improbable,
    must be true.

  2. #2
    Join Date
    Jun 2000
    Location
    Maputo, Maputo-Mozambique
    Posts
    96
    There is no money back guarentee on this one, but i think it can hep

    The following procedure provides a process dump for the Oracle database
    and shows all statistics for the PMON background process. Follow these
    steps:

    1. Start by issuing the ORADEBUG SETORAPID command to process 2. Process
    number 2 is the Oracle Process Monitor (PMON).

    SVRMGR> oradebug setorapid 2
    Unix process pid: 25159, image: ora_pmon_test

    2. Issue the PROCSTAT command to generate the statistics.

    SVRMGR> oradebug procstat
    Statement processed.

    3. Use the TRACEFILE_NAME command to find the location of the trace
    file.

    SVRMGR> oradebug TRACEFILE_NAME
    /app/oracle/admin/orcl/bdump/pmon_25159.trc

    Here's the listing from this procedure. As you can see, this provides
    detailed information regarding important PMON activities.

    SQL> !cat /u01/app/oracle/admin/prodc1/bdump/prodc1_pmon_25159.trc
    Dump file /u01/app/oracle/admin/prodc1/bdump/prodc1_pmon_25159.trc
    Oracle8i Enterprise Edition Release 8.1.6.1.0 - 64bit Production
    With the Partitioning option
    JServer Release 8.1.6.1.0 - 64bit Production
    ORACLE_HOME = /u01/app/oracle/product/8.1.6_64
    System name: SunOS
    Node name: burleson-01
    Release: 5.8
    Version: Generic_108528-03
    Machine: sun4u
    Instance name: prodc1
    Redo thread mounted by this instance: 1
    Oracle process number: 2
    Unix process pid: 25159, image: oracle@burleson-01 (PMON)

    *** 2001-07-04 12:13:25.042
    *** SESSION ID:(1.1) 2001-07-04 12:13:24.979
    ----- Dump of Process Statistics -----
    User level CPU time = 121
    System call CPU time = 47
    Other system trap CPU time = 0
    Text page fault sleep time = 0
    Data page fault sleep time = 0
    Kernel page fault sleep time = 0
    User lock wait sleep time = 0
    All other sleep time = 562367527
    Wait-cpu (latency) time = 0
    Minor page faults = 0
    Major page faults = 346
    Swaps = 0
    Input blocks = 251
    Output blocks = 0
    Messages sent = 0
    Messages received = 0
    Signals received = 1827660
    Voluntary context switches = 1828280
    Involuntary context switches = 58531459
    System calls = 141934171
    Chars read and written = 28650
    Process heap size = 1425416
    Process stack size = 565248


    Regrads
    Alexandre
    In god i trust

  3. #3
    Join Date
    Nov 2000
    Posts
    245

    Can I use oradebug to check the listener cpu usage? if yes, how.

    thanks

  4. #4
    Join Date
    Apr 2001
    Location
    London
    Posts
    725
    Thanks for your help alexandre.
    Once you have eliminated all of the impossible,
    whatever remains however improbable,
    must be true.

  5. #5
    Join Date
    Apr 2001
    Location
    London
    Posts
    725
    Hi Alexnadre..

    I take it that this has no overhead..

    Does the oradebug command simply take a dump (snapshot) or does it continue adding info to trace file ?

    Is there a need to stop it ?

    Thanks
    Suresh
    Once you have eliminated all of the impossible,
    whatever remains however improbable,
    must be true.

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