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Date: Wed, 4 Sep 2019 15:17:37 +0530
From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
Naveen N Rao <naveen.n.rao@...ux.vnet.ibm.com>
Subject: [PATCH 1/2] perf/stat: Reset previous counts on repeat with interval
When using perf stat with repeat and interval option, perf stat shows
wrong values for events. The wrong values will be shown for the first
interval on the second and subsequent repetitions.
Without fix:
perf stat -r 3 -I 2000 -e faults -e sched:sched_switch -a sleep 5
2.000282489 53 faults
2.000282489 513 sched:sched_switch
4.005478208 3,721 faults
4.005478208 2,666 sched:sched_switch
5.025470933 395 faults
5.025470933 1,307 sched:sched_switch
2.009602825 1,84,46,74,40,73,70,95,47,520 faults <------
2.009602825 1,84,46,74,40,73,70,95,49,568 sched:sched_switch <------
4.019612206 4,730 faults
4.019612206 2,746 sched:sched_switch
5.039615484 3,953 faults
5.039615484 1,496 sched:sched_switch
2.000274620 1,84,46,74,40,73,70,95,47,520 faults <------
2.000274620 1,84,46,74,40,73,70,95,47,520 sched:sched_switch <------
4.000480342 4,282 faults
4.000480342 2,303 sched:sched_switch
5.000916811 1,322 faults
5.000916811 1,064 sched:sched_switch
prev_raw_counts is allocated when using intervals. This is used when
calculating the difference in the counts of events when using interval.
The current counts are stored in prev_raw_counts to calculate the
differences in the next iteration. On the first interval of the second
and subsequent repetitions, prev_raw_counts would be the values stored
in the last interval of the previous repetitions, while the current
counts will only be for the first interval of the current repetition.
Hence there is a possibility of events showing up as big number.
Fix this by resetting prev_raw_counts whenever perf stat repeats the
command.
With fix:
perf stat -r 3 -I 2000 -e faults -e sched:sched_switch -a sleep 5
2.019349347 2,597 faults
2.019349347 2,753 sched:sched_switch
4.019577372 3,098 faults
4.019577372 2,532 sched:sched_switch
5.019415481 1,879 faults
5.019415481 1,356 sched:sched_switch
2.000178813 8,468 faults
2.000178813 2,254 sched:sched_switch
4.000404621 7,440 faults
4.000404621 1,266 sched:sched_switch
5.040196079 2,458 faults
5.040196079 556 sched:sched_switch
2.000191939 6,870 faults
2.000191939 1,170 sched:sched_switch
4.000414103 541 faults
4.000414103 902 sched:sched_switch
5.000809863 450 faults
5.000809863 364 sched:sched_switch
Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
tools/perf/builtin-stat.c | 3 +++
tools/perf/util/stat.c | 17 +++++++++++++++++
tools/perf/util/stat.h | 1 +
3 files changed, 21 insertions(+)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 352cf39d7c2f..eda451842bfd 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1961,6 +1961,9 @@ int cmd_stat(int argc, const char **argv)
fprintf(output, "[ perf stat: executing run #%d ... ]\n",
run_idx + 1);
+ if (run_idx != 0)
+ perf_evlist__reset_prev_raw_counts(evsel_list);
+
status = run_perf_stat(argc, argv, run_idx);
if (forever && status != -1) {
print_counters(NULL, argc, argv);
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index db8a6cf336be..773f29d4f6a7 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -155,6 +155,15 @@ static void perf_evsel__free_prev_raw_counts(struct perf_evsel *evsel)
evsel->prev_raw_counts = NULL;
}
+static void perf_evsel__reset_prev_raw_counts(struct perf_evsel *evsel)
+{
+ if (evsel->prev_raw_counts) {
+ evsel->prev_raw_counts->aggr.val = 0;
+ evsel->prev_raw_counts->aggr.ena = 0;
+ evsel->prev_raw_counts->aggr.run = 0;
+ }
+}
+
static int perf_evsel__alloc_stats(struct perf_evsel *evsel, bool alloc_raw)
{
int ncpus = perf_evsel__nr_cpus(evsel);
@@ -205,6 +214,14 @@ void perf_evlist__reset_stats(struct perf_evlist *evlist)
}
}
+void perf_evlist__reset_prev_raw_counts(struct perf_evlist *evlist)
+{
+ struct perf_evsel *evsel;
+
+ evlist__for_each_entry(evlist, evsel)
+ perf_evsel__reset_prev_raw_counts(evsel);
+}
+
static void zero_per_pkg(struct perf_evsel *counter)
{
if (counter->per_pkg_mask)
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 7032dd1eeac2..9cd0d9cff374 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -194,6 +194,7 @@ void perf_stat__collect_metric_expr(struct perf_evlist *);
int perf_evlist__alloc_stats(struct perf_evlist *evlist, bool alloc_raw);
void perf_evlist__free_stats(struct perf_evlist *evlist);
void perf_evlist__reset_stats(struct perf_evlist *evlist);
+void perf_evlist__reset_prev_raw_counts(struct perf_evlist *evlist);
int perf_stat_process_counter(struct perf_stat_config *config,
struct perf_evsel *counter);
--
2.18.1
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