Re: [PATCH] timekeeping: drop irq-context clocksource polling

Thomas Gleixner
2007-04-08T08:32:46Z

On Sat, 2007-04-07 at 14:30 -0700, Daniel Walker wrote:
> On Sat, 2007-04-07 at 22:50 +0200, Thomas Gleixner wrote:
> > On Sat, 2007-04-07 at 10:43 -0700, Daniel Walker wrote:
> > > Looks like this path ,
> > >
> > > arch/i386/kernel/tsc.c: time_cpufreq_notifier(); <-- takes xtime_lock
> > > mark_tsc_unstable();
> > > clocksource_change_rating(&clocksource_tsc, 0);
> > > timekeeping_change_clocksource(); <-- takes xtime_lock
> > >
> > >
> > > I'm not sure why the time_cpufreq_notifier is taking the xtime_lock tho .
> >
> > Simply because it fiddles with variables which are relevant for
> > timekeeping.
>
> loops_per_jiffy perhaps?

Oh well, this is a leftover from the days where we tried to use TSC
despite of frequency changes. It still modifies the scale factor of the
tsc clocksource.

I agree that it can be removed as we switch off TSC anyway in that case.

tglx