Messages in this thread | | | Date | Wed, 27 Oct 2010 16:26:22 +0200 | From | Markus Trippelsdorf <> | Subject | Re: Clocksource tsc unstable (delta = -8589361717 ns) in current git |
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On Tue, Oct 26, 2010 at 12:18:56PM -0700, john stultz wrote: > On Tue, 2010-10-26 at 17:48 +0200, Thomas Gleixner wrote: > > On Tue, 26 Oct 2010, Markus Trippelsdorf wrote: > > > On Tue, Oct 26, 2010 at 03:18:43PM +0200, Borislav Petkov wrote: > > > > otherwise, I don't see anything strange in your dmesg. Unless tglx has a > > > > better idea, I'd ask you to bisect it. 5618 changesets shouldn't be that > > > > much but I don't know, if the issue appears every several hours it could > > > > still be tedious. > > > > > > That would be a several week long process, as the issue appears ~ every > > > 2 days here on this machine running 24/7. > > > > There is only a single commit in that area post 2.6.36: > > > > 8af3c153baf95374eff20a37f00c59a295b52756 > > > > But I have a hard time how this should make this happen. John ? > > Yea, that one doesn't look connected to me. > > There have been a few cases that I've seen where we can get false > positives for bad TSCs due to the watchdog clocksource having problems > (or the clocksource watchdog thread getting delayed for such a long time > the watchdog clocksource wraps and we then can't validly compare the two > - although this would be hard to trigger with non-rt kernels).
I think the remark above points in the right direction, because the mysterious slowness happened again today (and this time on a vanilla git kernel). But this time no "Clocksource tsc unstable" message appeared in the kernel log. My system recovered by itself and after 2 minutes of slowness it was usable again. (The symptoms were the same as desribed in my first mail: Second long delays when typing and switching from X to the console took many seconds.)
Is there anything I can do to pinpoint the cause of this slowdown should it happen again? (Maybe a perf timechart?)
-- Markus
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