Re: [BUG] cpufreq: constant cpu_khz

Peter Zijlstra
2008-08-25T19:27:25Z

On Mon, 2008-08-25 at 11:22 -0700, Arjan van de Ven wrote:
> On Mon, 25 Aug 2008 19:57:12 +0200
> Ingo Molnar <mingo@elte.hu> wrote:
>
> >
> > * Dave Jones <davej@codemonkey.org.uk> wrote:
> >
> > > > hm, that too is due to the tsc.c unification - Alok Cc:-ed.
> > > > Applied your fix to x86/urgent.
> > >
> > > ACKed-by: Dave Jones <davej@redhat.com>
> > >
> > > Good catch Peter. I'm puzzled how that bug was latent on 64bit for
> > > so long with no-one realising though.
> >
> > i think it's the combination of these two factors:
> >
> > - bootup frequently is typically full-speed, so we calibrate things
> > right
> >
> > - cpufreq events are relatively slow-scale - and when they trigger
> > the system is definitely not under load. So how precisely the
> > scheduler functions isnt all that important in such scenarios -
> > there's tons of CPU power available.
> >
>
> - many many of the 64 bit capable cpus are constant-tsc anyway

Ironically I noticed it first on 64bit ;-)