Re: [PATCH 5/5] perf annotate: Add --skip-empty option

From: Namhyung Kim
Date: Mon Aug 05 2024 - 16:14:49 EST


On Mon, Aug 05, 2024 at 04:22:12PM -0300, Arnaldo Carvalho de Melo wrote:
> On Sat, Aug 03, 2024 at 02:13:32PM -0700, Namhyung Kim wrote:
> > Like in perf report, we want to hide empty events in the perf annotate
> > output. This is consistent when the option is set in perf report.
> >
> > For example, the following command would use 3 events including dummy.
> >
> > $ perf mem record -a -- perf test -w noploop
> >
> > $ perf evlist
> > cpu/mem-loads,ldlat=30/P
> > cpu/mem-stores/P
> > dummy:u
> >
> > Just using perf annotate with --group will show the all 3 events.
>
> Seems unrelated, just before compiling with this patch:
>
> root@x1:~# perf mem record -a -- perf test -w noploop
> Memory events are enabled on a subset of CPUs: 4-11
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 10.506 MB perf.data (2775 samples) ]
> root@x1:~#
>
> root@x1:~# perf annotate --group --stdio2 sched_clock
> root@x1:~# perf annotate --stdio2 sched_clock
> Samples: 178 of event 'cpu_atom/mem-stores/P', 4000 Hz, Event count (approx.): 565268, [percent: local period]
> sched_clock() /usr/lib/debug/lib/modules/6.8.11-200.fc39.x86_64/vmlinux
> Percent 0xffffffff810511e0 <sched_clock>:
> endbr64
> 5.76 incl pcpu_hot+0x8
> 5.47 → callq sched_clock_noinstr
> 88.78 decl pcpu_hot+0x8
> ↓ je 1e
> → jmp __x86_return_thunk
> 1e: → callq __SCT__preempt_schedule_notrace
> → jmp __x86_return_thunk
> root@x1:~# perf annotate --group --stdio2 sched_clock
> root@x1:~# perf annotate --group --stdio sched_clock
> root@x1:~# perf annotate --group sched_clock
> root@x1:~#
>
> root@x1:~# perf evlist
> cpu_atom/mem-loads,ldlat=30/P
> cpu_atom/mem-stores/P
> dummy:u
> root@x1:~#
>
> root@x1:~# perf report --header-only | grep cmdline
> # cmdline : /home/acme/bin/perf mem record -a -- perf test -w noploop
> root@x1:~#
>
> I thought it would be some hybrid oddity but seems to be just --group
> related, seems like it stops if the first event has no samples? Because
> it works with another symbol:

Good catch. Yeah I found it only checked the first event. Something
like below should fix the issue.

Thanks,
Namhyung


diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index efcadb7620b8..8d3ec439b783 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -632,11 +632,15 @@ static int __cmd_annotate(struct perf_annotate *ann)
evlist__for_each_entry(session->evlist, pos) {
struct hists *hists = evsel__hists(pos);
u32 nr_samples = hists->stats.nr_samples;
+ struct evsel *evsel;

- if (nr_samples == 0)
+ if (!symbol_conf.event_group || !evsel__is_group_leader(pos))
continue;

- if (!symbol_conf.event_group || !evsel__is_group_leader(pos))
+ for_each_group_member(evsel, pos)
+ nr_samples += evsel__hists(evsel)->stats.nr_samples;
+
+ if (nr_samples == 0)
continue;

hists__find_annotations(hists, pos, ann);