[lkml]   [2010]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [patch] Remove the per cpu tick skew
    On Tue, Jul 27, 2010 at 9:02 PM, Arjan van de Ven <> wrote:
    > the following patch is a win for power management on x86....
    > ... but since this touches generic code.. are there any
    > other architectures that would be negatively affected by this?

    It was added to avoid contention when all the cpus grabbed the
    xtime_lock (causing latency spikes of timer overhead * number of
    cpus). We don't grab the xtime lock everywhere anymore, so that
    shouldn't bite us, but I'm curious if there are not other global locks
    taken that may see extra contention without this change.

    > Subject: [patch] Remove the per cpu tick skew
    > Historically, Linux has tried to make the regular timer tick on the various
    > CPUs not happen at the same time, to avoid contention on xtime_lock.
    > Nowadays, with the tickless kernel, this contention no longer happens
    > since time keeping and updating are done differently. In addition,
    > this skew is actually hurting power consumption in a measurable
    > way on many-core systems.
    > Signed-off-by: Arjan van de Ven <>

    I'll give it a spin against -rt and see if we show any latency jumps.


     \ /
      Last update: 2010-07-28 22:29    [W:0.020 / U:29.196 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site