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SubjectRe: [PATCH 2/4] perf annotate: Avoid division by zero when calculating percent
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Hi Arnaldo :)

Here the perf.data is,
https://www.dropbox.com/s/nr4nnv8g3cipluf/perf.data?dl=1&pl=1

I tested as below.

$ perf record -e "{cycles,page-faults,branch-misses}" ./old <input.txt

$ perf annotate --stdio -l -f 2> /dev/null | grep -i nan | head -3
29.04 -nan 1.52 old_pack_knapsack.c:34
28.27 -nan 0.00 old_pack_knapsack.c:38
16.37 -nan 0.00 old_pack_knapsack.c:37


Thanks,
Taeung

On 03/21/2017 03:15 AM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Mar 20, 2017 at 11:56:55AM +0900, Taeung Song escreveu:
>> Currently perf-annotate with --print-line can print
>> -nan(0x8000000000000) because of division by zero
>> when calculating percent.
>>
>> So if a sum of samples is zero, skip calculating percent.
>
> Tried to reproduce it here, couldn't, syswide record:
>
> [root@jouet ~]# perf evlist -v
> cycles: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
> [root@jouet ~]# perf annotate --stdio -l 2> /dev/null | grep -i nan
> [root@jouet ~]#
>
> Can you please send me a perf.data file with this problem? I have to go
> thru the code to see how this can take place...
>
> - Arnaldo
>
>
>> 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)
>>
>> ...
>>
>> 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)
>>
>> ...
>>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Jiri Olsa <jolsa@redhat.com>
>> Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
>> ---
>> 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 fc91c6b..9bb43cd 100644
>> --- a/tools/perf/util/annotate.c
>> +++ b/tools/perf/util/annotate.c
>> @@ -1665,11 +1665,15 @@ 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)
>> --
>> 2.7.4

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