perf report: Don't bother locking when adding hist entries
The 'perf report'command is single-threaded, so no need to grab a lock.
Although the fast path of pthread_mutex_[un]lock() is very fast, there's
a ~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 <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1368497347-9628-6-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
1 file changed