Technical information about /onecpu option in boot.ini

Discussion in 'Windows XP Hardware' started by Vampy20, Jul 17, 2008.

  1. Vampy20

    Vampy20 Guest

    In Windows XP you can set the option /onecpu in the boot.ini file, to force
    Windows to run on one cpu when running on a multicore system.

    Can anybody give me link to a page or document where I can get some
    information about what exactly happens when booting with this option?

    I want to know if the second (or the other) core(s) are disabled or not. Is
    it possible that a other program can run on the other cores??

    Thanks,
    Vampy
     
    Vampy20, Jul 17, 2008
    #1
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  2. Vampy20 wrote:
    > In Windows XP you can set the option /onecpu in the boot.ini file,
    > to force Windows to run on one cpu when running on a multicore
    > system.
    >
    > Can anybody give me link to a page or document where I can get some
    > information about what exactly happens when booting with this
    > option?
    >
    > I want to know if the second (or the other) core(s) are disabled or
    > not. Is it possible that a other program can run on the other
    > cores??


    The boot.ini options will only allow Windows to see/utilize however many
    CPU/cores you specify. (/numproc= is the one you should probably be using.)

    /NUMPROC=
    This switch sets the number of processors that Windows NT will run at
    startup. This will help test out performance problems and defective CPUs.
    For example, /NUMPROC=3

    /ONECPU
    This switch is part of Compaq's HAL. The switch tells Windows NT to use only
    1 CPU at startup. This will enable you to run a single CPU in a multikernel
    configuration. For example, /ONECPU.

    If you use /numproc=1 on a system with multiple cores - you end up with only
    one core being used and the other cores are *not* available in your windows
    session. You can set the affinity manually through task manager for a given
    process - or you can use one of many applications to start an application
    with different affinity depending on your needs.

    --
    Shenan Stanley
    MS-MVP
    --
    How To Ask Questions The Smart Way
    http://www.catb.org/~esr/faqs/smart-questions.html
     
    Shenan Stanley, Jul 17, 2008
    #2
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