Messages in this thread | | | Date | Tue, 7 Feb 2012 12:07:13 +0100 | Subject | Re: [PATCH] perf: fix assertion failure in x86_pmu_start() | From | Stephane Eranian <> |
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On Tue, Feb 7, 2012 at 11:49 AM, Ingo Molnar <mingo@elte.hu> wrote: > > * Stephane Eranian <eranian@google.com> wrote: > >> On Tue, Feb 7, 2012 at 11:25 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote: >> > Le mardi 07 février 2012 à 09:41 +0100, Ingo Molnar a écrit : >> > >> >> Were these messages introduced by: >> >> >> >> e050e3f0a71b: perf: Fix broken interrupt rate throttling >> >> >> >> as well? >> >> >> >> In any case I'm holding off on applying the patch before this is >> >> resolved. >> > >> > Reverting e050e3f0a71b solves all my problems, no more warnings. >> > >> > $ perf record -a -g hackbench 10 thread 4000 >> > Running with 10*40 (== 400) tasks. >> > Time: 13.181 >> > [ perf record: Woken up 59 times to write data ] >> > [ perf record: Captured and wrote 16.874 MB perf.data (~737228 samples) >> > ] >> > >> > $ perf record -a -g hackbench 10 thread 4000 >> > Running with 10*40 (== 400) tasks. >> > Time: 13.124 >> > [ perf record: Woken up 61 times to write data ] >> > [ perf record: Captured and wrote 16.533 MB perf.data (~722349 samples) >> > ] >> > >> >> What system is this running on? >> The problem is that without e050e3f0a71b interrupt throttling does not work. > > Fixes are not supposed to regress, so if we cannot resolve this > within a couple of days we'll have to revert e050e3f0a71b and > re-try it later. > I suspect in the case of Eric's system, the fact that we do not stop the PMU when adjusting frequency anymore may expose a side-effect of his BIOS "sharing" the PMU with perf_events. But the config value reported by the kernel does not include the INT bit, i.e., the counter does not generate interrupts on overflow, so it should not conflict.
>> I think the key difference is that without the patch, >> frequency adjustment happens with the PMU completely stopped >> whereas with my patch it does not. I suspect this may be the >> issue. I can rework the patch to disable the PMU completely >> while retaining the same workflow. > > Would be nice to try that. > > Thanks, > > Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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