Messages in this thread | | | Subject | Re: [BUG nohz]: wrong user and system time accounting | From | Mike Galbraith <> | Date | Thu, 30 Mar 2017 15:35:22 +0200 |
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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.
-Mike
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