Re: question about RCU dynticks_nesting

From: Mike Galbraith
Date: Wed May 06 2015 - 03:01:55 EST


On Wed, 2015-05-06 at 08:52 +0200, Mike Galbraith wrote:
> On Tue, 2015-05-05 at 23:06 -0700, Paul E. McKenney wrote:
>
> > > 100000000 * stat() on isolated cpu
> > >
> > > NO_HZ_FULL off inactive housekeeper nohz_full
> > > real 0m14.266s 0m14.367s 0m20.427s 0m27.921s
> > > user 0m1.756s 0m1.553s 0m1.976s 0m10.447s
> > > sys 0m12.508s 0m12.769s 0m18.400s 0m17.464s
> > > (real) 1.000 1.007 1.431 1.957
>
>
> > Does the attached patch help at all?
>
> nohz_full
> 0m27.073s
> 0m9.423s
> 0m17.602s
>
> Not a complete retest, and a pull in between, but I'd say that's a no.

(well, a second is a nice "at all", just not a _huge_ "at all";)

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