Re: clocksource change of behavior in 2.6.22 compared to 2.6.20 causes massive system clock slowdown

[Alessandro Suardi]

On 7/10/07, john stultz <johnstul@xxxxxxxxxx> wrote:
> On Tue, 2007-07-10 at 00:29 -0700, Andrew Morton wrote:
> > On Mon, 9 Jul 2007 16:27:59 +0200 "Alessandro Suardi" <alessandro.suardi@xxxxxxxxx> wrote:
> >
> > > My oldish AMD K7-800's clock began falling behind after
> > >  rebooting from 2.6.20 (and 109 days uptime with a spotless
> > >  clock) into 2.6.22; time lost is about four minutes each hour.
> > >
> > > Turns out that 2.6.22 marks my TSC as unstable and starts
> > >  using PIT instead. Rebooting 2.6.22 with clocksource=tsc
> > >  gets the original stable system time back.
>
> Alessandro,
> Can you send me dmesg output for 2.6.20 and 2.6.22 (without
> clocksource=tsc)?

Actually, I lied a little bit - it was 2.6.22 with clock=tsc (which
warns on boot about clock= being deprecated in favor of
clocksource= ). I assume behavior is identical for now.

Please find attached the dmesg ring (incomplete, as the
kernel ring size I have seems too small to hold the full
buffer, but it seems to have all the interesting stuff) of
2.6.20, 2.6.22, 2.6.22 with clock=tsc.

If you need more info, just ask. I'll be out of the country
from July 12 to the morning of July 16, and again from
July 17 to July 20, so if you'd rather get at this later on,
it's okay for me ;)

thanks, ciao,

--alessandro

"Did you get married but forgot to get divorced ?"

    (Danny and Dusty, 'The Good Old Days')

Attachment: dmesg-2620
Description: Binary data

Attachment: dmesg-2622
Description: Binary data

Attachment: dmesg-2622-clock.tsc
Description: Binary data