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SubjectRe: [PATCH] perf annotate: Fix sample events lost in stdio mode
Hi,

On Thu, Mar 11, 2021 at 5:48 PM Yang Jihong <yangjihong1@huawei.com> wrote:
>
> Hello,
>
> On 2021/3/6 16:28, Yang Jihong wrote:
> > In hist__find_annotations function, since have a hist_entry per IP for the 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.

I'm not sure it's still true that we have a hist_entry per IP.
Afaik the default sort key is comm,dso,sym which means it should have a single
hist_entry for each symbol. It seems like an old comment..

> >
> > 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 add a u8 member to struct sym_hist and use a bit to
> > indicate whether the symbol has been processed.
> > Because different types of event correspond to different sym_hist, no conflict
> > occurs.
> > ---
> > tools/perf/builtin-annotate.c | 22 ++++++++++++++--------
> > tools/perf/util/annotate.h | 4 ++++
> > 2 files changed, 18 insertions(+), 8 deletions(-)
> >
> > diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> > index a23ba6bb99b6..c8c67892ae82 100644
> > --- a/tools/perf/builtin-annotate.c
> > +++ b/tools/perf/builtin-annotate.c
> > @@ -372,15 +372,21 @@ static void hists__find_annotations(struct hists *hists,
> > if (next != NULL)
> > nd = next;
> > } else {
> > - hist_entry__tty_annotate(he, evsel, ann);
> > + struct sym_hist *h = annotated_source__histogram(notes->src,
> > + evsel->idx);
> > +
> > + if (h->processed == 0) {
> > + hist_entry__tty_annotate(he, evsel, ann);
> > +
> > + /*
> > + * Since we have a hist_entry per IP for the same
> > + * symbol, set processed flag of evsel in sym_hist
> > + * to signal we already processed this symbol.
> > + */
> > + h->processed = 1;
> > + }
> > +
> > 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);
> > }
> > }
> > }
> > diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
> > index 096cdaf21b01..89872bfdc958 100644
> > --- a/tools/perf/util/annotate.h
> > +++ b/tools/perf/util/annotate.h
> > @@ -228,6 +228,10 @@ void symbol__calc_percent(struct symbol *sym, struct evsel *evsel);
> > struct sym_hist {
> > u64 nr_samples;
> > u64 period;
> > +
> > + u8 processed : 1, /* whether symbol has been processed, used for annotate */
> > + __reserved : 7;

I think just a bool member is fine.

> > +
> > struct sym_hist_entry addr[];
> > };
> >
> >
> Please check whether this solution is feasible, look forward to your review.

What about this? (not tested)

diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index a23ba6bb99b6..a91fe45bd69f 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);
}
}
}
Thanks,
Namhyung

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