linux-kernel - [PATCH 2/3] perf hist: Do not skip elided fields when processing samples

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Date:	Sat, 28 Nov 2015 02:32:38 +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@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>
Subject: [PATCH 2/3] perf hist: Do not skip elided fields when processing samples

If user gives a filter, perf marks the corresponding column elided and
omits the output.  But it should process and aggregates samples using
the field, otherwise samples will be aggregated as if the column was not
there resulted in incorrect output.

For example, I'd like to set a filter on native_write_msr_safe.  The
original overhead of the function is negligible.

  $ perf report | grep native_write_msr_safe
      0.00%  swapper  [kernel.vmlinux]  native_write_msr_safe
      0.00%  perf     [kernel.vmlinux]  native_write_msr_safe

However adding -S option gives different output.

  $ perf report -S native_write_msr_safe --percentage absolute | \
  > grep -e swapper -e perf
     51.47%  swapper  [kernel.vmlinux]
      4.14%  perf     [kernel.vmlinux]

Since it aggregated samples using comm and dso only.  In fact, the above
values are same when it sorts with -s comm,dso.

  $ perf report -s comm,dso | grep -e swapper -e perf
     51.47%  swapper  [kernel.vmlinux]
      4.14%  perf     [kernel.vmlinux]

This resulted in TUI failure with -ERANGE since it tries to increase
sample hit count for annotation with wrong symbols due to incorrect
aggregation.

This patch fixes it not to skip elided fields when comparing samples
in order to insert them to the hists.

Reported-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/hist.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 4fd37d6708cb..6e8e0ee9ec37 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -924,9 +924,6 @@ hist_entry__cmp(struct hist_entry *left, struct hist_entry *right)
 	int64_t cmp = 0;
 
 	perf_hpp__for_each_sort_list(fmt) {
-		if (perf_hpp__should_skip(fmt))
-			continue;
-
 		cmp = fmt->cmp(fmt, left, right);
 		if (cmp)
 			break;
@@ -942,9 +939,6 @@ hist_entry__collapse(struct hist_entry *left, struct hist_entry *right)
 	int64_t cmp = 0;
 
 	perf_hpp__for_each_sort_list(fmt) {
-		if (perf_hpp__should_skip(fmt))
-			continue;
-
 		cmp = fmt->collapse(fmt, left, right);
 		if (cmp)
 			break;
-- 
2.6.2

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