Re: [PATCH v4] perf annotate: Fix sample events lost in stdio mode

[Yang Jihong]

Hi,

On 2021/3/13 11:06, Namhyung Kim wrote:
> On Sat, Mar 13, 2021 at 11:16 AM Yang Jihong <yangjihong1@xxxxxxxxxx> wrote:
> > In hist__find_annotations function, since different hist_entry may point to same
> > symbol, we free notes->src to signal already processed this symbol in stdio mode;
> > when annotate, entry will skipped if notes->src is NULL to avoid repeated output.
> >
> > However, there is a problem, for example, run the following command:
> >
> >   # perf record -e branch-misses -e branch-instructions -a sleep 1
> >
> > perf.data file contains different types of sample event.
> >
> > If the same IP sample event exists in branch-misses and branch-instructions,
> > this event uses the same symbol. When annotate branch-misses events, notes->src
> > corresponding to this event is set to null, as a result, when annotate
> > branch-instructions events, this event is skipped and no annotate is output.
> >
> > Solution of this patch is to remove zfree in hists__find_annotations and
> > change sort order to "dso,symbol" to avoid duplicate output when different
> > processes correspond to the same symbol.
>
> Looks good.  But I'm not sure about the branch stack mode.
> I suspect we can use the same sort key there.
>
> Jin Yao, what do you think?
>
> Thanks,
> Namhyung
Is it changed to the following?
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -374,13 +374,6 @@ static void hists__find_annotations(struct hists 
*hists,
                } else {
                        hist_entry__tty_annotate(he, evsel, ann);
                        nd = rb_next(nd);
-                       /*
-                        * Since we have a hist_entry per IP for the same
-                        * symbol, free he->ms.sym->src to signal we already
-                        * processed this symbol.
-                        */
-                       zfree(&notes->src->cycles_hist);
-                       zfree(&notes->src);
                }
        }
 }
@@ -619,6 +612,12 @@ int cmd_annotate(int argc, const char **argv)

        setup_browser(true);

+       /*
+        * Events of different processes may correspond to the same
+        * symbol, we do not care about the processes in annotate,
+        * set sort order to avoid repeated output.
+        */
+       sort_order = "dso,symbol";
        if ((use_browser == 1 || annotate.use_stdio2) && 
annotate.has_br_stack) {
                sort__mode = SORT_MODE__BRANCH;
                if (setup_sorting(annotate.session->evlist) < 0)

I think branch stack mode also don't care about the processes.

> > ---
> >   tools/perf/builtin-annotate.c | 13 ++++++-------
> >   1 file changed, 6 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> > index a23ba6bb99b6..ad169e3e2e8f 100644
> > --- a/tools/perf/builtin-annotate.c
> > +++ b/tools/perf/builtin-annotate.c
> > @@ -374,13 +374,6 @@ static void hists__find_annotations(struct hists *hists,
> >                  } else {
> >                          hist_entry__tty_annotate(he, evsel, ann);
> >                          nd = rb_next(nd);
> > -                       /*
> > -                        * Since we have a hist_entry per IP for the same
> > -                        * symbol, free he->ms.sym->src to signal we already
> > -                        * processed this symbol.
> > -                        */
> > -                       zfree(&notes->src->cycles_hist);
> > -                       zfree(&notes->src);
> >                  }
> >          }
> >   }
> > @@ -624,6 +617,12 @@ int cmd_annotate(int argc, const char **argv)
> >                  if (setup_sorting(annotate.session->evlist) < 0)
> >                          usage_with_options(annotate_usage, options);
> >          } else {
> > +               /*
> > +                * Events of different processes may correspond to the same
> > +                * symbol, we do not care about the processes in annotate,
> > +                * set sort order to avoid repeated output.
> > +                */
> > +               sort_order = "dso,symbol";
> >                  if (setup_sorting(NULL) < 0)
> >                          usage_with_options(annotate_usage, options);
> >          }
> > --
> > 2.30.GIT
> .