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    SubjectRe: [tbench regression fixes]: digging out smelly deadmen.
    Date
    On Saturday, 25 of October 2008, David Miller wrote:
    > From: "Rafael J. Wysocki" <rjw@sisk.pl>
    > Date: Sat, 25 Oct 2008 00:25:34 +0200
    >
    > > On Friday, 10 of October 2008, Ingo Molnar wrote:
    > > >
    > > > * Evgeniy Polyakov <s0mbre@tservice.net.ru> wrote:
    > > >
    > > > > On Fri, Oct 10, 2008 at 01:42:45PM +0200, Ingo Molnar (mingo@elte.hu) wrote:
    > > > > > > vanilla 27: 347.222
    > > > > > > no TSO/GSO: 357.331
    > > > > > > no hrticks: 382.983
    > > > > > > no balance: 389.802
    > > > > >
    > > > > > okay. The target is 470 MB/sec, right? (Assuming the workload is sane
    > > > > > and 'fixing' it does not mean we have to schedule worse.)
    > > > >
    > > > > Well, that's where I started/stopped, so maybe we will even move
    > > > > further? :)
    > > >
    > > > that's the right attitude ;)
    > >
    > > Can anyone please tell me if there was any conclusion of this thread?
    >
    > I made some more analysis in private with Ingo and Peter Z. and found
    > that the tbench decreases correlate pretty much directly with the
    > ongoing increasing cpu cost of wake_up() and friends in the fair
    > scheduler.
    >
    > The largest increase in computational cost of wakeups came in 2.6.27
    > when the hrtimer bits got added, it more than tripled the cost of a wakeup.
    > In 2.6.28-rc1 the hrtimer feature has been disabled, but I think that
    > should be backports into the 2.6.27-stable branch.

    Thanks a lot for the info.

    Could you please give me a pointer to the commit disabling the hrtimer feature?

    Rafael


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