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    SubjectRe: [BUG nohz]: wrong user and system time accounting
    On Thu, Mar 30, 2017 at 03:35:22PM +0200, Mike Galbraith wrote:
    > On Thu, 2017-03-30 at 09:02 -0400, Rik van Riel wrote:
    > > On Thu, 2017-03-30 at 14:51 +0200, Frederic Weisbecker wrote:
    >
    > > > Also, why does it raise power consumption issues?
    > >
    > > On a system without either nohz_full or nohz idle
    > > mode, skewed ticks result in CPU cores waking up
    > > at different times, and keeping an idle system
    > > consuming power for more time than it would if all
    > > the ticks happened simultaneously.
    >
    > And if your server farm is mostly idle, that power savings may delay
    > your bankruptcy proceedings by a whole microsecond ;-)
    >
    > Or more seriously, what skew does do on boxen of size X today is
    > something for perf to say. At the time, removal was very bad for my 8
    > socket box, and allegedly caused huge SGI beasts in horrific pain.

    I see.
    Nohz_full is already bad for powersavings anyway. CPU 0 always ticks :-)

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