linux-kernel - [PATCH] perf tools: Fix to put caller above callee in children mode

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Date:   Mon, 22 May 2017 21:50:29 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Jiri Olsa <jolsa@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel-team@....com,
        Frederic Weisbecker <fweisbec@...il.com>,
        Milian Wolff <milian.wolff@...b.com>
Subject: [PATCH] perf tools: Fix to put caller above callee in children mode

The __hpp__sort_acc() sorts entries using callchain depth in order to
put callers above in children mode.  But it assumed the callchain order
was callee-first.  Now default (for children) is caller-first so the
order of entries is reverted.

For example, consider following case.

  $ perf report --no-children
  ..l
  # Overhead  Command  Shared Object        Symbol
  # ........  .......  ...................  ..........................
  #
      99.44%  a.out    a.out                [.] main
              |
              ---main
                 __libc_start_main
                 _start

Then children mode should show 'start' above '__libc_start_main' since
it's the caller (parent) of the __libc_start_main.  But it's reversed:

  # Children      Self  Command  Shared Object    Symbol
  # ........  ........  .......  ...............  .....................
  #
      99.61%     0.00%  a.out    libc-2.25.so     [.] __libc_start_main
      99.61%     0.00%  a.out    a.out            [.] _start
      99.54%    99.44%  a.out    a.out            [.] main

This patch fixes it.

  # Children      Self  Command  Shared Object    Symbol
  # ........  ........  .......  ...............  .....................
  #
      99.61%     0.00%  a.out    a.out            [.] _start
      99.61%     0.00%  a.out    libc-2.25.so     [.] __libc_start_main
      99.54%    99.44%  a.out    a.out            [.] main

Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Milian Wolff <milian.wolff@...b.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/ui/hist.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index 59addd52d9cd..ddb2c6fbdf91 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -210,6 +210,8 @@ static int __hpp__sort_acc(struct hist_entry *a, struct hist_entry *b,
 			return 0;
 
 		ret = b->callchain->max_depth - a->callchain->max_depth;
+		if (callchain_param.order == ORDER_CALLER)
+			ret = -ret;
 	}
 	return ret;
 }
-- 
2.13.0