Messages in this thread | | | Date | Tue, 1 Oct 2013 10:48:53 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/2] perf tool: don't print bogus data on -e cycles |
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* Ramkumar Ramachandra <artagnon@gmail.com> wrote:
> When only the cycles event is requested: > > $ perf stat -e cycles dd if=/dev/zero of=/dev/null count=1000000 > 1000000+0 records in > 1000000+0 records out > 512000000 bytes (512 MB) copied, 0.26123 s, 2.0 GB/s > > Performance counter stats for 'dd if=/dev/zero of=/dev/null count=1000000': > > 911,626,453 cycles # 0.000 GHz > > 0.262113350 seconds time elapsed > > The 0.000 GHz comment in the output is totally bogus and misleading. It > happens because update_shadow_stats() doesn't touch runtime_nsecs_stats; > it is only written when a requested counter matches a SW_TASK_CLOCK. In > our case, since we have only requested HW_CPU_CYCLES, > runtime_nsecs_stats is unavailable. So, omit printing the comment > altogether. > > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> > Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> > --- > tools/perf/builtin-stat.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-)
Acked-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
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