Re: [PATCH 1/13] timestamp fixes

From: Andrew Theurer (habanero_at_us.ibm.com)
Date: 02/28/05

  • Next message: Chad N. Tindel: "Scheduler question in __wake_up_common() - Real Time Apps" 
    Date:	Mon, 28 Feb 2005 12:11:18 -0600
To: mingo@elte.hu, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org

    Nick, can you describe the system you run the DB tests on? Do you have
    any cpu idle time stats and hopefully some context switch rate stats?

    I think I understand the concern [patch 6] of stealing a task from one
    node to an idle cpu in another node, but I wonder if we can have some
    sort of check for idle balance: if the domain/node to steal from has
    some idle cpu somewhere, we do not steal, period. To do this we have a
    cpu_idle bitmask, we update as cpus go idle/busy, and we reference this
    cpu_idle & sd->cpu_mask to see if there's at least one cpu that's idle.

    > Ingo wrote:
    >
    > But i expect fork/clone balancing to be almost certainly a problem. (We
    > didnt get it right for all workloads in 2.6.7, and i think it cannot be
    > gotten right currently either, without userspace API help - but i'd be
    > happy to be proven wrong.)

    Perhaps initially one could balance on fork up to the domain level which
    has task_hot_time=0, up to a shared cache by default. Anything above
    that could require a numactl like preference from userspace.

    -Andrew Theurer
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  • Next message: Chad N. Tindel: "Scheduler question in __wake_up_common() - Real Time Apps"

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