On Thu, Feb 02, 2017 at 05:09:16PM +0100, Ingo Molnar wrote:
> If there's any doubt about the validity of the measurement I'd suggest doing:
>
> perf stat -a --sync --repeat 3 ...
>
> ... so that there's no perf overhead and skew from the many processes of a
> kernel
> build workload, plus the --sync should reduce IO related noise.
>
> Or:
>
> perf stat --null --sync --repeat 3 ...
>
> ... will only measure elapsed time, but will do that very precisely and with
> very
> little overhead.
Yeah, I was talking to Peter about the -a thing on IRC... I think I'm going to
try that. Here's the full command I was using:
./tools/perf/perf stat -e
task-clock,context-switches,cache-misses,cpu-migrations,page-faults,cycles,instructions,branches,branch-misses
--repeat 3 --sync --pre ~/bin/pre-build-kernel.sh -- make -s -j17 bzImage
I think I stole it from you from some mail thread we had in the past.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
