Messages in this thread | | | Date | Mon, 3 Apr 2017 16:40:49 +0200 | From | Frederic Weisbecker <> | Subject | Re: [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 :-)
| |