Messages in this thread Patch in this message | | | Subject | Re: [PATCH 2/4] perf annotate: Avoid division by zero when calculating percent | From | Taeung Song <> | Date | Tue, 21 Mar 2017 07:11:13 +0900 |
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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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