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| author | Jiri Olsa <jolsa@kernel.org> | 2017-07-26 15:02:06 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2017-07-26 20:25:44 +0300 |
| commit | 82bf311e15d22e2fa45423b1fb4a21cf925381fe (patch) | |
| tree | ed6f171f8cd8f07e3e2966a0116cae3a75929d02 /tools/perf/util/evsel.c | |
| parent | f7794d525447f1e4e4b2228dd29dba084005e6bf (diff) | |
| download | linux-82bf311e15d22e2fa45423b1fb4a21cf925381fe.tar.xz | |
perf stat: Use group read for event groups
Make perf stat use group read if there are groups defined. The group
read will get the values for all member of groups within a single
syscall instead of calling read syscall for every event.
We can see considerable less amount of kernel cycles spent on single
group read, than reading each event separately, like for following perf
stat command:
# perf stat -e {cycles,instructions} -I 10 -a sleep 1
Monitored with "perf stat -r 5 -e '{cycles:u,cycles:k}'"
Before:
24,325,676 cycles:u
297,040,775 cycles:k
1.038554134 seconds time elapsed
After:
25,034,418 cycles:u
158,256,395 cycles:k
1.036864497 seconds time elapsed
The perf_evsel__open fallback changes contributed by Andi Kleen.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170726120206.9099-4-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
| -rw-r--r-- | tools/perf/util/evsel.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 89aecf3a35c7..3735c9e0080d 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -49,6 +49,7 @@ static struct { bool clockid_wrong; bool lbr_flags; bool write_backward; + bool group_read; } perf_missing_features; static clockid_t clockid; @@ -1321,6 +1322,7 @@ perf_evsel__set_count(struct perf_evsel *counter, int cpu, int thread, count->val = val; count->ena = ena; count->run = run; + count->loaded = true; } static int @@ -1677,6 +1679,8 @@ fallback_missing_features: if (perf_missing_features.lbr_flags) evsel->attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS | PERF_SAMPLE_BRANCH_NO_CYCLES); + if (perf_missing_features.group_read && evsel->attr.inherit) + evsel->attr.read_format &= ~(PERF_FORMAT_GROUP|PERF_FORMAT_ID); retry_sample_id: if (perf_missing_features.sample_id_all) evsel->attr.sample_id_all = 0; @@ -1832,6 +1836,12 @@ try_fallback: perf_missing_features.lbr_flags = true; pr_debug2("switching off branch sample type no (cycles/flags)\n"); goto fallback_missing_features; + } else if (!perf_missing_features.group_read && + evsel->attr.inherit && + (evsel->attr.read_format & PERF_FORMAT_GROUP)) { + perf_missing_features.group_read = true; + pr_debug2("switching off group read\n"); + goto fallback_missing_features; } out_close: do { |