Re: [PATCH 0/13] Time: Generic Timeofday Subsystem (v B10)

Ingo Molnar
2005-11-15T20:54:13Z

* john stultz <johnstul@us.ibm.com> wrote:

> > idle=poll does seem to fix the major clock drift problem. There may
> > still be an issue, but it's much smaller:
> >
> > 2.6.14-mm2-todb10:
> > 14 Nov 21:50:57 offset: -0.025373 drift: -22404.0 ppm
> > 14 Nov 21:51:59 offset: -1.577053 drift: -24985.4603175 ppm
> > 14 Nov 21:53:00 offset: -3.104569 drift: -25012.9032258 ppm
> >
> > 2.6.14-mm2-todb10 with idle=poll:
> > 14 Nov 21:37:59 offset: 5.9e-05 drift: 63.0 ppm
> > 14 Nov 21:39:00 offset: 0.003207 drift: 51.7903225806 ppm
>
> Hmm. It seems the c3 compensation is triggering when it shouldn't, or
> maybe its over compensating.
>
> I can't reproduce it on my laptop. Do you recall if in previous tests
> you saw anything like this? I'm trying to narrow down if its just a
> difference in hardware or if something in the c3 idle code changed.

it's with an earlier queue of yours, but maybe it's related: i have a
report that HPET causes HRT inaccuracies (e.g. sleeps for 20 msecs last
21 msecs). If all HPET options are turned off in the .config then
everything is fine and accurate.

Ingo