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    SubjectRe: [tbench regression fixes]: digging out smelly deadmen.
    Hi Ingo.

    On Fri, Oct 10, 2008 at 11:15:11AM +0200, Ingo Molnar (mingo@elte.hu) wrote:

    > >
    > > I use tsc clocksource, also available acpi_pm and jiffies,
    > > with acpi_pm performance is even lower (I stopped test after it dropped
    > > below 340 MB/s mark), jiffies do not work at all, looks like sockets
    > > stuck in time_wait state when this clock source is used, although that
    > > may be some different issue.
    > >
    > > So I think hrticks are guilty, but still not as good as .25 tree without
    > > mentioned changes (455 MB/s) and .24 (475 MB/s).
    >
    > i'm glad that you are looking into this! That is an SMP box, right? If
    > yes then could you try this sched-domains tuning utility i have written
    > yesterday (incidentally):
    >
    > http://redhat.com/~mingo/cfs-scheduler/tune-sched-domains

    I've removed SD_BALANCE_NEWIDLE:
    # ./tune-sched-domains $[191-2]
    changed /proc/sys/kernel/sched_domain/cpu0/domain0/flags: 191 => 189
    SD flag: 189
    + 1: SD_LOAD_BALANCE: Do load balancing on this domain
    - 2: SD_BALANCE_NEWIDLE: Balance when about to become idle
    + 4: SD_BALANCE_EXEC: Balance on exec
    + 8: SD_BALANCE_FORK: Balance on fork, clone
    + 16: SD_WAKE_IDLE: Wake to idle CPU on task wakeup
    + 32: SD_WAKE_AFFINE: Wake task to waking CPU
    - 64: SD_WAKE_BALANCE: Perform balancing at task wakeup
    + 128: SD_SHARE_CPUPOWER: Domain members share cpu power
    changed /proc/sys/kernel/sched_domain/cpu0/domain1/flags: 47 => 189
    SD flag: 189
    + 1: SD_LOAD_BALANCE: Do load balancing on this domain
    - 2: SD_BALANCE_NEWIDLE: Balance when about to become idle
    + 4: SD_BALANCE_EXEC: Balance on exec
    + 8: SD_BALANCE_FORK: Balance on fork, clone
    + 16: SD_WAKE_IDLE: Wake to idle CPU on task wakeup
    + 32: SD_WAKE_AFFINE: Wake task to waking CPU
    - 64: SD_WAKE_BALANCE: Perform balancing at task wakeup
    + 128: SD_SHARE_CPUPOWER: Domain members share cpu power

    And got noticeble improvement (each new line has fixes from previous):

    vanilla 27: 347.222
    no TSO/GSO: 357.331
    no hrticks: 382.983
    no balance: 389.802

    > and please, when tuning such scheduler bits, could you run latest
    > tip/master:
    >
    > http://people.redhat.com/mingo/tip.git/README
    >
    > and you need to have CONFIG_SCHED_DEBUG=y enabled for the tuning knobs.
    >
    > so that it's all in sync with upcoming scheduler changes/tunings/fixes.

    Ok, I've started to pull it down, I will reply back when things are
    ready.

    --
    Evgeniy Polyakov


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