Messages in this thread | | | Subject | Re: CFS Bandwidth Control - Test results of cgroups tasks pinned vs unpinnede | From | Peter Zijlstra <> | Date | Fri, 16 Sep 2011 10:28:40 +0200 |
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On Fri, 2011-09-16 at 01:14 -0700, Paul Turner wrote: > On 09/13/11 11:23, Peter Zijlstra wrote: > > On Tue, 2011-09-13 at 23:31 +0530, Srivatsa Vaddagiri wrote: > >> * Peter Zijlstra<a.p.zijlstra@chello.nl> [2011-09-13 16:19:39]: > >> > >>>> Booting with "nohz=off" also helps significantly. > >>>> > >>>> With nohz=on, average idle time (over 1 min) is 10.3% > >>>> With nohz=off, average idle time (over 1 min) is 3.9% > > I think more compelling here is that it looks like nohz load-balance > needs more love.
Quite probable, although I do know we tend to go overboard in going into nohz state too.
> > That's not what I said.. what I said is that the nohz code should also > > use the idle time prognosis.. disabling the tick is a costly operation, > > doing it only to have to undo it costs time, and will be accounted to > > idle time, hence your improvement with nohz=off. > > > > Enabling Venki's CONFIG_IRQ_TIME_ACCOUNTING=y would discount to provide > a definitive answer here yes?
Ah, yes, its all (soft)irq context anyway, no need to also account systemcalls.
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