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authorNamhyung Kim <namhyung.kim@lge.com>2013-05-14 11:09:03 +0900
committerArnaldo Carvalho de Melo <acme@redhat.com>2013-05-28 16:24:00 +0300
commitf3dd19817e5bbcae81e96571a3d42aa30a1581fb (patch)
tree46ef8e5ffa7347f397961c96751e8c391c50eab7 /tools
parent27a0dcb7adb52473dd98d285a46b764b9219d303 (diff)
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>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/builtin-report.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 63febd24e91..0f0cf2472d9 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;
}