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    SubjectRE: Why HZ on i386 is 100 ?
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    On Tue, 2002-04-16 at 09:18, BALBIR SINGH wrote:
    > I remember seeing somewhere unix system VII used to have HZ set to 60
    > for the machines built in the 70's. I wonder if todays pentium iiis and ivs
    > should still use HZ of 100, though their internal clock is in GHz.
    >
    > I think somethings in the kernel may be tuned for the value of HZ, these
    > things would be arch specific.
    >
    > Increasing the HZ on your system should change the scheduling behaviour,
    > it could lead to more aggresive scheduling and could affect the
    > behaviour of the VM subsystem if scheduling happens more frequently. I am
    > just guessing, I do not know.
    >

    I remember reading that a higher HZ value will make your machine more
    responsive, but will also mean that each running process will have a
    smaller CPU time slice and that the kernel will spend more CPU time
    scheduling at the expense of processes.


    HTH

    Liam Girdwood

    > Changing though trivial would require a good look at all the code that
    > uses HZ.
    >
    > Comments,
    > Balbir
    >
    > |-----Original Message-----
    > |From: linux-kernel-owner@vger.kernel.org
    > |[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of William Lee
    > |Irwin III
    > |Sent: Tuesday, April 16, 2002 1:45 PM
    > |To: Olaf Fraczyk
    > |Cc: linux-kernel@vger.kernel.org
    > |Subject: Re: Why HZ on i386 is 100 ?
    > |
    > |
    > |On Tue, Apr 16, 2002 at 09:47:48AM +0200, Olaf Fraczyk wrote:
    > |> Hi,
    > |> I would like to know why exactly this value was choosen.
    > |> Is it safe to change it to eg. 1024? Will it break anything?
    > |> What else should I change to get it working:
    > |> CLOCKS_PER_SEC?
    > |> Please CC me.
    > |> Regards,
    > |> Olaf Fraczyk
    > |
    > |I tried a few times running with HZ == 1024 for some testing (or I guess
    > |just to see what happened). I didn't see any problems, even without the
    > |obscure CLOCKS_PER_SEC ELF business.
    > |
    > |
    > |Cheers,
    > |Bill
    > |-
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    >

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    --
    Liam Girdwood
    l_girdwood@bitwise.co.uk (Work)
    liam@nova-ioe.org (Home)

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