On Tue, May 14, 2013 at 11:09:03AM +0900, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung....@lge.com>
>
> The perf report is single-threaded, so no need to grab a lock.
> Although the fast path of pthread_mutex_[un]lock() is very fast,
> there's ~3% gain by eliminating it when we have huge sample data.
>
> $ perf record -a -F 100000 -o perf.data.bench -- perf bench sched all
> $ perf record -e cycles:upp -o perf.data.before -- \
> > perf report -i perf.data.bench --stdio > /dev/null
> ... apply this patch ...
> $ perf record -e cycles:upp -o perf.data.after -- \
> > perf report -i perf.data.bench --stdio > /dev/null
> $ perf diff perf.data.{before,after} | grep pthread
> +0.02% libpthread-2.15.so [.] _pthread_cleanup_push_defer
> +0.02% libpthread-2.15.so [.] _pthread_cleanup_pop_restore
> 0.05% -0.05% perf [.] pthread_mutex_unlock@plt
> 0.05% -0.05% perf [.] pthread_mutex_lock@plt
> 1.01% -1.01% libpthread-2.15.so [.] pthread_mutex_lock
> 1.68% -1.68% libpthread-2.15.so [.] __pthread_mutex_unlock_usercnt
> 0.05% -0.05% libpthread-2.15.so [.] pthread_mutex_unlock
>
> Signed-off-by: Namhyung Kim <namhy...@kernel.org>
> ---
> tools/perf/builtin-report.c | 4 ----
> 1 file changed, 4 deletions(-)
nice :)
Acked-by: Jiri Olsa <jo...@redhat.com>
jirka
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