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Message-ID: <1430895708.3693.10.camel@gmail.com>
Subject: Re: question about RCU dynticks_nesting
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: paulmck@linux.vnet.ibm.com
Cc: Rik van Riel <riel@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>,
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        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 06 May 2015 09:01:48 +0200
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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";)