2021-03-12 03:09:22

by Yang Jihong

Subject: [PATCH v2] perf annotate: Fix sample events lost in stdio mode

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.

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 bool member "processed_flag" in struct sym_hist
to indicate whether the symbol has been processed.
Because different types of event correspond to different sym_hist, no conflict
occurs.
---

Changes since v1:
- Change processed flag variable from u8 to bool.

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..6cd6612dbff6 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_flag) {
+ 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_flag = true;
+ }
+
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..9d071c9879c1 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;
+
+ /* whether symbol has been processed, used for annotate */
+ bool processed_flag;
+
struct sym_hist_entry addr[];
};

--
2.30.GIT