Commit-ID: a1f3d56761df31f0ffeb215b974e26d5613e92a4
Gitweb: http://git.kernel.org/tip/a1f3d56761df31f0ffeb215b974e26d5613e92a4
Author: Namhyung Kim <namhyung@xxxxxxxxxx>
AuthorDate: Fri, 13 May 2016 15:01:03 +0900
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 16 May 2016 23:11:47 -0300
perf stat: Use cpu-clock event for cpu targets
Currently 'perf stat' always counts task-clock event by default. But
it's somewhat confusing for system-wide targets (especially with 'sleep
N' as the 'sleep' task just sleeps and doesn't use cputime). Changing
to cpu-clock event instead for that case makes more sense IMHO.
Before:
# perf stat -a sleep 0.1
Performance counter stats for 'system wide':
403.038603 task-clock (msec) # 4.001 CPUs utilized
150 context-switches # 0.372 K/sec
7 cpu-migrations # 0.017 K/sec
71 page-faults # 0.176 K/sec
23,705,169 cycles # 0.059 GHz
15,888,166 instructions # 0.67 insn per cycle
3,326,078 branches # 8.253 M/sec
87,643 branch-misses # 2.64% of all branches
0.100737009 seconds time elapsed
#
After:
# perf stat -a sleep 0.1
Performance counter stats for 'system wide':
404.271182 cpu-clock (msec) # 4.000 CPUs utilized
143 context-switches # 0.354 K/sec
13 cpu-migrations # 0.032 K/sec
73 page-faults # 0.181 K/sec
22,119,220 cycles # 0.055 GHz
13,622,065 instructions # 0.62 insn per cycle
2,918,769 branches # 7.220 M/sec
85,033 branch-misses # 2.91% of all branches
0.101073089 seconds time elapsed
#
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1463119263-5569-3-git-send-email-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-stat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 16a923c..efdd232 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1905,6 +1905,9 @@ static int add_default_attributes(void)
}
if (!evsel_list->nr_entries) {
+ if (target__has_cpu(&target))
+ default_attrs0[0].config = PERF_COUNT_SW_CPU_CLOCK;
+
if (perf_evlist__add_default_attrs(evsel_list, default_attrs0) < 0)
return -1;
if (pmu_have_event("cpu", "stalled-cycles-frontend")) {
--
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