[PATCH 22/66] perf report: Don't bother locking when adding hist entries
From: Arnaldo Carvalho de Melo
Date: Thu May 30 2013 - 12:06:18 EST
From: Namhyung Kim <namhyung.kim@xxxxxxx>
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@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1368497347-9628-6-git-send-email-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-report.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 63febd2..0f0cf24 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -312,8 +312,6 @@ static int process_sample_event(struct perf_tool *tool,
if (rep->cpu_list && !test_bit(sample->cpu, rep->cpu_bitmap))
return 0;
- pthread_mutex_lock(&evsel->hists.lock);
-
if (sort__mode == SORT_MODE__BRANCH) {
ret = perf_report__add_branch_hist_entry(tool, &al, sample,
evsel, machine);
@@ -332,8 +330,6 @@ static int process_sample_event(struct perf_tool *tool,
if (ret < 0)
pr_debug("problem incrementing symbol period, skipping event\n");
}
- pthread_mutex_unlock(&evsel->hists.lock);
-
return ret;
}
--
1.8.1.4
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