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

Started byNamhyung Kim <namhyung@kernel.org>
First post2015-11-27 18:40 +0100
Last post2015-11-29 09:00 +0100
Articles 3 — 3 participants

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  [PATCH 2/3] perf hist: Do not skip elided fields when processing samples Namhyung Kim <namhyung@kernel.org> - 2015-11-27 18:40 +0100
    Re: [PATCH 2/3] perf hist: Do not skip elided fields when processing  samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-11-28 02:00 +0100
    [tip:perf/core] perf hists:   Do not skip elided fields when processing samples tip-bot for Namhyung Kim <tipbot@zytor.com> - 2015-11-29 09:00 +0100

#1278900 — [PATCH 2/3] perf hist: Do not skip elided fields when processing samples

FromNamhyung Kim <namhyung@kernel.org>
Date2015-11-27 18:40 +0100
Subject[PATCH 2/3] perf hist: Do not skip elided fields when processing samples
Message-ID<qzva1-5TV-9@gated-at.bofh.it>
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@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.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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#1279049 — Re: [PATCH 2/3] perf hist: Do not skip elided fields when processing samples

FromArnaldo Carvalho de Melo <acme@kernel.org>
Date2015-11-28 02:00 +0100
SubjectRe: [PATCH 2/3] perf hist: Do not skip elided fields when processing samples
Message-ID<qzC1P-1Bx-1@gated-at.bofh.it>
In reply to#1278900
Em Sat, Nov 28, 2015 at 02:32:38AM +0900, Namhyung Kim escreveu:
> 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.

Thanks, applied, I've tested it and it now seems to work in both the
--stdio and --tui interfaces, good job!

- Arnaldo
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#1279288 — [tip:perf/core] perf hists: Do not skip elided fields when processing samples

Fromtip-bot for Namhyung Kim <tipbot@zytor.com>
Date2015-11-29 09:00 +0100
Subject[tip:perf/core] perf hists: Do not skip elided fields when processing samples
Message-ID<qA53Q-3nY-21@gated-at.bofh.it>
In reply to#1278900
Commit-ID:  e72655d97d24fff559b4ab59de791c3741a74c8c
Gitweb:     http://git.kernel.org/tip/e72655d97d24fff559b4ab59de791c3741a74c8c
Author:     Namhyung Kim <namhyung@kernel.org>
AuthorDate: Sat, 28 Nov 2015 02:32:38 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 27 Nov 2015 21:42:13 -0300

perf hists: 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.

Commiter note:

After the patch, with a different workloads:

  # perf report --show-total-period -S native_write_msr_safe --stdio
  #
  # symbol: native_write_msr_safe
  #
  # Samples: 455  of event 'cycles:pp'
  # Event count (approx.): 134787489
  #
  # Overhead Period Command         Shared Object
  # ........ ...... ............... ................
  #
       0.22% 293081 qemu-system-x86 [vmlinux]
       0.19% 255914 swapper         [vmlinux]
       0.00%   2054 Timer           [vmlinux]
       0.00%   1021 firefox         [vmlinux]
       0.00%      2 perf            [vmlinux]

  # perf report --show-total-period | grep native_write_msr_safe
  Failed to open /tmp/perf-14838.map, continuing without symbols
       0.22% 293081 qemu-system-x86 [vmlinux]  [k] native_write_msr_safe
       0.19% 255914 swapper         [vmlinux]  [k] native_write_msr_safe
       0.00%   2054 Timer           [vmlinux]  [k] native_write_msr_safe
       0.00%   1021 firefox         [vmlinux]  [k] native_write_msr_safe
       0.00%      2 perf            [vmlinux]  [k] native_write_msr_safe
  #

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1448645559-31167-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 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 4fd37d6..6e8e0ee 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;
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