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perf stat: Fix interval output values

PATCH New Jiri Olsa 2 participants 2 messages Feb 3, 2016 – Feb 4, 2016 perf events

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Jiri Olsa

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PATCH 1/1 perf stat: Fix interval output values

We broke interval data displays with commit:
3f416f22d1e2 perf stat: Do not clean event's private stats

This commit removed stats cleaning, which is important for '-r' option to carry counters data over the whole run. But it's necessary to clean it for interval mode, otherwise the displayed value is avg of all previous values.

Before:

  $ perf stat -e cycles -a -I 1000 record
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791        107,823,524      cycles
  $ perf stat report
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791         91,519,906      cycles

Now:

  $ perf stat report
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791        107,823,524      cycles

Notice the second value being bigger (91,.. < 107,..).

This could be easily verified by using perf script which displays raw stat data:

  $ perf script
  CPU   THREAD             VAL             ENA             RUN            TIME EVENT
    0       -1        23855779      1000209530      1000209530      1000240796 cycles
    1       -1        33340397      1000224964      1000224964      1000240796 cycles
    2       -1        15835415      1000226695      1000226695      1000240796 cycles
    3       -1         2184696      1000228245      1000228245      1000240796 cycles
    0       -1        97014312      2000514533      2000514533      2000512791 cycles
    1       -1        46121497      2000543795      2000543795      2000512791 cycles
    2       -1        32269530      2000543566      2000543566      2000512791 cycles
    3       -1         7634472      2000544108      2000544108      2000512791 cycles

The sum of the first 4 values is the first interval aggregated value:
23855779 + 33340397 + 15835415 + 2184696 = 75,216,287

The sum of the second 4 values minus first value is
the second interval aggregated value:
97014312 + 46121497 + 32269530 + 7634472 - 75216287 = 107,823,524

Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/perf/util/stat.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
tools/perf/util/stat.c +10 -0
index beeed0bd3bee..4d9b481cf3b6 100644
@@ -311,6 +311,16 @@ int perf_stat_process_counter(struct perf_stat_config *config,
 
 	aggr->val = aggr->ena = aggr->run = 0;
 
+	/*
+	 * We calculate counter's data every interval,
+	 * and the display code shows ps->res_stats
+	 * avg value. We need to zero the stats for
+	 * interval mode, otherwise overall avg running
+	 * averages will be shown for each interval.
+	 */
+	if (config->interval)
+		init_stats(ps->res_stats);
+
 	if (counter->per_pkg)
 		zero_per_pkg(counter);
Signature · 1 line
2.4.3
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#1 lore raw
perf stat: Fix interval output values
Commit-ID:  51fd2df1e882a3c2a3f4b6c9ff243a93c9046dba
Gitweb:     http://git.kernel.org/tip/51fd2df1e882a3c2a3f4b6c9ff243a93c9046dba
Author:     Jiri Olsa <[email protected]>
AuthorDate: Wed, 3 Feb 2016 08:43:56 +0100
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 3 Feb 2016 19:39:52 -0300

perf stat: Fix interval output values

We broke interval data displays with commit:

3f416f22d1e2 ("perf stat: Do not clean event's private stats")

This commit removed stats cleaning, which is important for '-r' option to carry counters data over the whole run. But it's necessary to clean it for interval mode, otherwise the displayed value is avg of all previous values.

Before:

  $ perf stat -e cycles -a -I 1000 record
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791        107,823,524      cycles
  $ perf stat report
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791         91,519,906      cycles

Now:

  $ perf stat report
  #           time             counts unit events
       1.000240796         75,216,287      cycles
       2.000512791        107,823,524      cycles

Notice the second value being bigger (91,.. < 107,..).

This could be easily verified by using perf script which displays raw stat data:

  $ perf script
  CPU  THREAD       VAL         ENA         RUN        TIME EVENT
    0      -1  23855779  1000209530  1000209530  1000240796 cycles
    1      -1  33340397  1000224964  1000224964  1000240796 cycles
    2      -1  15835415  1000226695  1000226695  1000240796 cycles
    3      -1   2184696  1000228245  1000228245  1000240796 cycles
    0      -1  97014312  2000514533  2000514533  2000512791 cycles
    1      -1  46121497  2000543795  2000543795  2000512791 cycles
    2      -1  32269530  2000543566  2000543566  2000512791 cycles
    3      -1   7634472  2000544108  2000544108  2000512791 cycles

The sum of the first 4 values is the first interval aggregated value:

23855779 + 33340397 + 15835415 + 2184696 = 75,216,287

The sum of the second 4 values minus first value is the second interval aggregated value:

97014312 + 46121497 + 32269530 + 7634472 - 75216287 = 107,823,524

Signed-off-by Jiri Olsa <[email protected]>
Cc Andi Kleen <[email protected]>
Cc David Ahern <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Stephane Eranian <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/util/stat.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
tools/perf/util/stat.c +10 -0
index 2b58edc..afb0c45 100644
@@ -311,6 +311,16 @@ int perf_stat_process_counter(struct perf_stat_config *config,
 
 	aggr->val = aggr->ena = aggr->run = 0;
 
+	/*
+	 * We calculate counter's data every interval,
+	 * and the display code shows ps->res_stats
+	 * avg value. We need to zero the stats for
+	 * interval mode, otherwise overall avg running
+	 * averages will be shown for each interval.
+	 */
+	if (config->interval)
+		init_stats(ps->res_stats);
+
 	if (counter->per_pkg)
 		zero_per_pkg(counter);