linux-kernel - Re: [BUG] cpufreq: constant cpu

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Message-Id: <1219685675.1979.5.camel@alok-dev1>
Date:	Mon, 25 Aug 2008 10:34:35 -0700
From:	Alok Kataria <akataria@...are.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	davej <davej@...emonkey.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [BUG] cpufreq: constant cpu_khz

On Mon, 2008-08-25 at 05:39 -0700, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@...radead.org> wrote:
> 
> > > I noticed that my sched_clock() was slow on a number of machine, so
> > > I started looking at cpufreq.
> >
> > The below seems to fix the problem for me, but I don't have enough
> > clue to know if its the correct fix, please advise.
> 
> > -     set_cyc2ns_scale(tsc_khz_ref, freq->cpu);
> > +     set_cyc2ns_scale(tsc_khz, freq->cpu);
> 
> hm, that too is due to the tsc.c unification - Alok Cc:-ed. Applied your
> fix to x86/urgent.
> 

Yes the fix is correct, tsc_khz can change in the loop above.
Looking at tsc_64.c before the integration, that too had this bug but
32bit was good. So this is the right fix.

Thanks,
Alok


>         Ingo

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