This is a note to let you know that I've just added the patch titled
perf stat: Fix interval output values
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-stat-fix-interval-output-values.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 51fd2df1e882a3c2a3f4b6c9ff243a93c9046dba Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@xxxxxxxxxx>
Date: Wed, 3 Feb 2016 08:43:56 +0100
Subject: perf stat: Fix interval output values
From: Jiri Olsa <jolsa@xxxxxxxxxx>
commit 51fd2df1e882a3c2a3f4b6c9ff243a93c9046dba upstream.
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 <jolsa@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1454485436-20639-1-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jeremy Linton <jeremy.linton@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/perf/util/stat.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -311,6 +311,16 @@ int perf_stat_process_counter(struct per
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);
Patches currently in stable-queue which might be from jolsa@xxxxxxxxxx are
queue-4.4/perf-stat-fix-interval-output-values.patch
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