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    SubjectRe: [patch] CFS (Completely Fair Scheduler), v2

    * Gene Heskett <> wrote:

    > This one (v2-rc2) is not a keeper I'm sorry to say, Ingo. v2-rc0 was
    > much better. Watching amanda run with htop, kmails composer is being
    > subjected to 5 to 10 second pauses, and htop says that gzip -best
    > isn't getting more that 15% of the cpu, and the /amandatapes drive is
    > being written to in a regular pattern that seems to be the cause of
    > the pauses according to gkrellm, which also seems to track the size of
    > the writes, and can show anything from 4.3k to 54 megs as being
    > written in one cycle of its screen update.

    ok - fortunately the delta between -v2-rc0 and -v2-final is pretty
    small. One difference is the child-runs-first fix. To restore the
    parent-runs-first logic, do this:

    echo 0 > /proc/sys/kernel/sched_child_runs_first

    does this make any difference?

    If not then pretty much the only other change was the nice level tweak i
    did. Could you try to grab a few snapshots of scheduling state via
    something like:

    while sleep 1; do cat /proc/sched_debug >> to-ingo.txt; done

    (and tell me the PID of the kmail composer, to make sure i'm checking
    the right task's behavior.)

    also, as a separate experiment, could you perhaps run this script as

    cd /proc; for N in [1-9]*; do renice -n 0 $N; done

    this will move all tasks in the system to nice level 0 and should make
    any nice level handling logic in the scheduler irrelevant. Do you have X
    reniced perhaps?

    Lots of system threads have negative or positive nice levels, so once
    you have executed this script, only a reboot will be a practical way to
    restore it to the previous settings.

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      Last update: 2007-04-17 08:21    [W:0.026 / U:9.324 seconds]
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