Re: CFS review

From: Ingo Molnar
Date: Wed Aug 01 2007 - 08:23:37 EST



* Roman Zippel <zippel@xxxxxxxxxxxxxx> wrote:

> On Wed, 1 Aug 2007, Ingo Molnar wrote:
>
> > > [...] e.g. in this example there are three tasks that run only for
> > > about 1ms every 3ms, but they get far more time than should have
> > > gotten fairly:
> > >
> > > 4544 roman 20 0 1796 520 432 S 32.1 0.4 0:21.08 lt
> > > 4545 roman 20 0 1796 344 256 R 32.1 0.3 0:21.07 lt
> > > 4546 roman 20 0 1796 344 256 R 31.7 0.3 0:21.07 lt
> > > 4547 roman 20 0 1532 272 216 R 3.3 0.2 0:01.94 l
> >
> > Mike and me have managed to reproduce similarly looking 'top' output,
> > but it takes some effort: we had to deliberately run a non-TSC
> > sched_clock(), CONFIG_HZ=100, !CONFIG_NO_HZ and !CONFIG_HIGH_RES_TIMERS.
>
> I used my old laptop for these tests, where tsc is indeed disabled due
> to instability. Otherwise the kernel was configured with
> CONFIG_HZ=1000.

please send all the debug info and source code we asked for - thanks!

Ingo
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