Messages in this thread | | | Date | Wed, 8 Feb 2012 16:23:37 +0100 | Subject | Re: [BUG] perf: perf sched warning possibly due to clock granularity on AMD | From | Stephane Eranian <> |
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On Wed, Feb 8, 2012 at 4:22 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote: > On Wed, Feb 08, 2012 at 04:10:24PM +0100, Stephane Eranian wrote: >> On Wed, Feb 8, 2012 at 4:07 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote: >> > On Mon, Feb 06, 2012 at 02:25:46PM +0100, Stephane Eranian wrote: >> >> Hi, >> >> >> >> I am running 3.3.30-rc2 on an AMD Bulldozer system in 64-bit mode. >> >> I was testing perf sched and I ran into an issue. That issue seems >> >> to exist only on AMD and not on Intel systems. It is not PMU related >> >> because I am doing tracing. >> >> >> >> I am running a simple ping pong test to stress the context switch >> >> code. Two processes exchanging a byte through a pipe (program provided >> >> below). >> >> >> >> Then, I capture a trace using perf sched, and I run sched lat, but >> >> on certain runs, I get: >> >> >> >> $ perf sched rec pong 2 >> >> $ perf sched lat >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: Timestamp below last timeslice flush >> >> Warning: TimesFound 4934 unknown events! >> >> Is this an older tool processing a perf.data file generated by a more recent tool? >> > >> > I've tried to reproduce this on an AMD phenom but haven't got any such >> > warning. >> > >> It does not happen at each run. > > Yeah I tried 5 times but wasn't lucky.
That's not enough!
> >> >> > Is there any chance you could "perf archive" your data and upload it somewhere >> > I can fetch it from? >> > >> I can send you the perf.data in a private Email. > > Thanks!
Will dig it up and send it to you. -- 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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