Messages in this thread | | | Date | Wed, 8 Feb 2012 16:22:03 +0100 | From | Frederic Weisbecker <> | Subject | Re: [BUG] perf: perf sched warning possibly due to clock granularity on AMD |
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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.
> > > 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.
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