Commit-ID: 2e933b1274dc89cd1629f6c7fd9bf952248d84c2
Gitweb: http://git.kernel.org/tip/2e933b1274dc89cd1629f6c7fd9bf952248d84c2
Author: Taeung Song <[email protected]>
AuthorDate: Mon, 27 Mar 2017 16:10:37 +0900
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Mon, 27 Mar 2017 15:04:56 -0300
perf annotate: Fix a bug of division by zero when calculating percent
Currently perf-annotate with --print-line can print
-nan(0x8000000000000) because of division by zero when calculating
percent. The division by zero happens when a sum of samples is zero in
symbol__get_source_line(), so fix it.
For example:
After running 'perf record' like below,
$ perf record -e "{cycles,page-faults,branch-misses}" ./a.out
Before:
$ perf annotate --stdio -l
Sorted summary for file /home/taeung/workspace/a.out
----------------------------------------------
32.89 -nan 7.04 a.c:38
25.14 -nan 0.00 a.c:34
16.26 -nan 56.34 a.c:31
15.88 -nan 1.41 a.c:37
5.67 -nan 0.00 a.c:39
1.13 -nan 35.21 a.c:26
0.95 -nan 0.00 a.c:44
0.57 -nan 0.00 a.c:32
Percent | Source code & Disassembly of a.out for cycles
(529 samples)
-----------------------------------------------------------------------------------------
:
...
a.c:26 0.57 -nan 4.23 : 40081a: mov
%edi,-0x24(%rbp)
a.c:26 0.00 -nan 9.86 : 40081d: mov
%rsi,-0x30(%rbp)
...
However, if a sum of samples is zero (e.g. 'page-faults'),
skip calculating percent.
After:
$ perf annotate --stdio -l
Sorted summary for file /home/taeung/workspace/a.out
----------------------------------------------
32.89 0.00 7.04 a.c:38
25.14 0.00 0.00 a.c:34
16.26 0.00 56.34 a.c:31
15.88 0.00 1.41 a.c:37
5.67 0.00 0.00 a.c:39
1.13 0.00 35.21 a.c:26
0.95 0.00 0.00 a.c:44
0.57 0.00 0.00 a.c:32
Percent | Source code & Disassembly of old for cycles
(529 samples)
-----------------------------------------------------------------------------------------
:
...
a.c:26 0.57 0.00 4.23 : 40081a: mov %edi,-0x24(%rbp)
a.c:26 0.00 0.00 9.86 : 40081d: mov %rsi,-0x30(%rbp)
...
Signed-off-by: Taeung Song <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Wang Nan <[email protected]>
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/annotate.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 6dc9148..11af5f0 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1671,11 +1671,15 @@ static int symbol__get_source_line(struct symbol *sym,
struct map *map,
src_line->nr_pcnt = nr_pcnt;
for (k = 0; k < nr_pcnt; k++) {
+ double percent = 0.0;
+
h = annotation__histogram(notes, evidx + k);
- src_line->samples[k].percent = 100.0 * h->addr[i] /
h->sum;
+ if (h->sum)
+ percent = 100.0 * h->addr[i] / h->sum;
- if (src_line->samples[k].percent > percent_max)
- percent_max = src_line->samples[k].percent;
+ if (percent > percent_max)
+ percent_max = percent;
+ src_line->samples[k].percent = percent;
}
if (percent_max <= 0.5)
