linux-kernel - [PATCH v5] perf annotate: Fix sample events lost in stdio mode

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Date:   Tue, 16 Mar 2021 10:17:59 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...hat.com>, <namhyung@...nel.org>,
        <yao.jin@...ux.intel.com>, <gustavoars@...nel.org>,
        <mliska@...e.cz>, <linux-kernel@...r.kernel.org>
CC:     <yangjihong1@...wei.com>, <zhangjinhao2@...wei.com>
Subject: [PATCH v5] perf annotate: Fix sample events lost in stdio mode

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.
---
 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..92c55f292c11 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);
 		}
 	}
 }
@@ -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)
-- 
2.30.GIT