Re: [PATCH v6] perf annotate: Fix sample events lost in stdio mode

[Yang Jihong]

Hello，

On 2021/3/18 14:13, Namhyung Kim wrote:

Hello,

On Wed, Mar 17, 2021 at 6:44 PM Yang Jihong <yangjiho...@huawei.com> 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.

Signed-off-by: Yang Jihong <yangjiho...@huawei.com>
---

Changes since v5:
   - Add Signed-off-by tag.

Changes since v4:
   - Use the same sort key "dso,symbol" in branch stack mode.

Changes since v3:
   - Modify the first line of comments.

Changes since v2:
   - Remove zfree in hists__find_annotations.
   - Change sort order to avoid duplicate output.

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

  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";

At this point, I think there's not much value having separate
setup_sorting() for branch mode.

I've resubmitted the patch for v7 as suggested below:
https://lore.kernel.org/patchwork/patch/1399031/

Is there anything else that needs to be modified?
Please take some time to review, thank you for your patience :)


Thanks,
Yang

Thanks,
Namhyung

         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

.