high CPU % in kernel mode - SUN

This is a discussion on high CPU % in kernel mode - SUN ; Hi, guys, When I run iostat or vmstat, I find 20% CPU is constantly in sysem mode (the sy column in the output). The user mode is less than 2%. In hours the system runs like that. I am trying ...

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Thread: high CPU % in kernel mode

  1. high CPU % in kernel mode

    Hi, guys,

    When I run iostat or vmstat, I find 20% CPU is constantly in sysem mode

    (the sy column in the output). The user mode is less than 2%. In hours

    the system runs like that. I am trying to figure out why the machine is

    constantly in kernel mode and what it is doing. When I use ps or
    prstat, the highest CPU usage of all the processes (including the
    system daemons) is around 1%. Most of them are 0.1%. I just don't know
    which process is contributing to the 20% kernel mode CPU usage.


    The machine is a 8 CPU box running solaris 8. It is a NFS client, not
    NFS server.


    I read some articles which say if the kernel mode CPu usage is
    constantly much hogher than the user mode, most likely the machine has
    some problem.


    Here come my questions:


    1) does CPU usage (%) reported by ps or prstat include the kernel mode
    CPU usage, if the process is make system calls?


    2) Do we have any way to figure out what the system is busy with?


    Thanks.


  2. Re: high CPU % in kernel mode


    bill_j_chen@yahoo.com wrote:

    >
    > 1) does CPU usage (%) reported by ps or prstat include the kernel mode
    > CPU usage, if the process is make system calls?


    yes

    > 2) Do we have any way to figure out what the system is busy with?
    >


    I like to start with:

    /usr/dt/bin/sdtprocess

    drop the sample time down to 5 seconds and you will get a good feel for
    what is running when and what sort of resources are being used.


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