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FAILED: patch "[PATCH] perf stat: Reset previous counts on repeat with interval" failed to apply to 5.3-stable tree

PATCH [email protected] 2 participants 2 messages Oct 8, 2019 – Oct 9, 2019

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#0 lore raw

The patch below does not apply to the 5.3-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b63fd11cced17fcb8e133def29001b0f6aaa5e06 Mon Sep 17 00:00:00 2001
From: Srikar Dronamraju <[email protected]>
Date: Wed, 4 Sep 2019 15:17:37 +0530
Subject: [PATCH] perf stat: Reset previous counts on repeat with interval

When using 'perf stat' with repeat and interval option, it shows wrong values for events.

The wrong values will be shown for the first interval on the second and subsequent repetitions.

Without the 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 the 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

#

Committer notes:

This was broken since the cset introducing the --interval feature, i.e. --repeat + --interval wasn't tested at that point, add the Fixes tag so that automatic scripts can pick this up.

Fixes 13370a9b5bb8 ("perf stat: Add interval printing")
Signed-off-by Srikar Dronamraju <[email protected]>
Acked-by Jiri Olsa <[email protected]>
Tested-by Arnaldo Carvalho de Melo <[email protected]>
Tested-by Ravi Bangoria <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Naveen N. Rao <[email protected]>
Cc Stephane Eranian <[email protected]>
Cc [email protected] # v3.9+
Link http://lore.kernel.org/lkml/[email protected] open here
[ Fixed up conflicts with libperf, i.e. some perf_{evsel,evlist} lost the 'perf' prefix ]
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
tools/perf/builtin-stat.c +3 -0
index eece3d1e429a..fa4b148ecfca 100644
@@ -1952,6 +1952,9 @@ 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);
tools/perf/util/stat.c +17 -0
index 06571209cb0b..fcd54342c04c 100644
@@ -162,6 +162,15 @@ static void perf_evsel__free_prev_raw_counts(struct evsel *evsel)
 	evsel->prev_raw_counts = NULL;
 }
 
+static void perf_evsel__reset_prev_raw_counts(struct 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 evsel *evsel, bool alloc_raw)
 {
 	int ncpus = perf_evsel__nr_cpus(evsel);

@@ -212,6 +221,14 @@ void perf_evlist__reset_stats(struct evlist *evlist)
 	}
 }
 
+void perf_evlist__reset_prev_raw_counts(struct evlist *evlist)
+{
+	struct evsel *evsel;
+
+	evlist__for_each_entry(evlist, evsel)
+		perf_evsel__reset_prev_raw_counts(evsel);
+}
+
 static void zero_per_pkg(struct evsel *counter)
 {
 	if (counter->per_pkg_mask)
tools/perf/util/stat.h +1 -0
index 0f9c9f6e2041..edbeb2f63e8d 100644
@@ -193,6 +193,7 @@ void perf_stat__collect_metric_expr(struct evlist *);
 int perf_evlist__alloc_stats(struct evlist *evlist, bool alloc_raw);
 void perf_evlist__free_stats(struct evlist *evlist);
 void perf_evlist__reset_stats(struct evlist *evlist);
+void perf_evlist__reset_prev_raw_counts(struct evlist *evlist);
 
 int perf_stat_process_counter(struct perf_stat_config *config,
 			      struct evsel *counter);
maintainer
#1 lore raw
Quoted 93 lines · On Tue, Oct 08, 2019 at 07:21:43PM +0200, [email protected] wrote:

The patch below does not apply to the 5.3-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b63fd11cced17fcb8e133def29001b0f6aaa5e06 Mon Sep 17 00:00:00 2001
From: Srikar Dronamraju <[email protected]>
Date: Wed, 4 Sep 2019 15:17:37 +0530
Subject: [PATCH] perf stat: Reset previous counts on repeat with interval

When using 'perf stat' with repeat and interval option, it shows wrong values for events.

The wrong values will be shown for the first interval on the second and subsequent repetitions.

Without the 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 the 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

#

Committer notes:

This was broken since the cset introducing the --interval feature, i.e. --repeat + --interval wasn't tested at that point, add the Fixes tag so that automatic scripts can pick this up.

Quoted 12 lines
Fixes 13370a9b5bb8 ("perf stat: Add interval printing")
Signed-off-by Srikar Dronamraju <[email protected]>
Acked-by Jiri Olsa <[email protected]>
Tested-by Arnaldo Carvalho de Melo <[email protected]>
Tested-by Ravi Bangoria <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Naveen N. Rao <[email protected]>
Cc Stephane Eranian <[email protected]>
Cc [email protected] # v3.9+
Link http://lore.kernel.org/lkml/[email protected] open here
[ Fixed up conflicts with libperf, i.e. some perf_{evsel,evlist} lost the 'perf' prefix ]
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>

Conflicts due to the perf_evsel -> evsel rename. Fixed up and queued for all kernels.

Signature · 2 lines
Thanks,
Sasha