linux-kernel - [PATCH 3/5] perf diff: Print diff result more precisely

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Date:	Sat, 27 Dec 2014 14:06:31 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH 3/5] perf diff: Print diff result more precisely

Current perf diff result is somewhat confusing since it sometimes hide
small result and sometimes there's no result.  So do not hide small
result (less than 0.01%) and print "N/A" if baseline is not
recorded (for ratio and wdiff only).  Blank means the baseline is
available but its pairs are not.

Before:

  # Baseline    Delta  Shared Object      Symbol
  # ........  .......  .................  .........................
  #
       ...
       0.01%   -0.01%  [kernel.kallsyms]  [k] native_write_msr_safe
       0.01%           [kernel.kallsyms]  [k] scheduler_tick
       0.01%           [kernel.kallsyms]  [k] native_read_msr_safe
       0.00%           [kernel.kallsyms]  [k] __rcu_read_unlock
                       [kernel.kallsyms]  [k] _raw_spin_lock
               +0.01%  [kernel.kallsyms]  [k] apic_timer_interrupt
                       [kernel.kallsyms]  [k] read_tsc

After:

  # Baseline    Delta  Shared Object      Symbol
  # ........  .......  .................  .........................
  #
       ...
       0.01%   -0.01%  [kernel.kallsyms]  [k] native_write_msr_safe
       0.01%           [kernel.kallsyms]  [k] scheduler_tick
       0.01%           [kernel.kallsyms]  [k] native_read_msr_safe
       0.00%           [kernel.kallsyms]  [k] __rcu_read_unlock
               +0.01%  [kernel.kallsyms]  [k] _raw_spin_lock
               +0.01%  [kernel.kallsyms]  [k] apic_timer_interrupt
               +0.01%  [kernel.kallsyms]  [k] read_tsc

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/builtin-diff.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 72c718e6549c..3f86737da2c4 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -788,7 +788,7 @@ static int __hpp__color_compare(struct perf_hpp_fmt *fmt,
 	char pfmt[20] = " ";
 
 	if (!pair)
-		goto dummy_print;
+		goto no_print;
 
 	switch (comparison_method) {
 	case COMPUTE_DELTA:
@@ -797,8 +797,6 @@ static int __hpp__color_compare(struct perf_hpp_fmt *fmt,
 		else
 			diff = compute_delta(he, pair);
 
-		if (fabs(diff) < 0.01)
-			goto dummy_print;
 		scnprintf(pfmt, 20, "%%%+d.2f%%%%", dfmt->header_width - 1);
 		return percent_color_snprintf(hpp->buf, hpp->size,
 					pfmt, diff);
@@ -830,6 +828,9 @@ static int __hpp__color_compare(struct perf_hpp_fmt *fmt,
 	}
 dummy_print:
 	return scnprintf(hpp->buf, hpp->size, "%*s",
+			dfmt->header_width, "N/A");
+no_print:
+	return scnprintf(hpp->buf, hpp->size, "%*s",
 			dfmt->header_width, pfmt);
 }
 
@@ -879,14 +880,15 @@ hpp__entry_pair(struct hist_entry *he, struct hist_entry *pair,
 		else
 			diff = compute_delta(he, pair);
 
-		if (fabs(diff) >= 0.01)
-			scnprintf(buf, size, "%+4.2F%%", diff);
+		scnprintf(buf, size, "%+4.2F%%", diff);
 		break;
 
 	case PERF_HPP_DIFF__RATIO:
 		/* No point for ratio number if we are dummy.. */
-		if (he->dummy)
+		if (he->dummy) {
+			scnprintf(buf, size, "N/A");
 			break;
+		}
 
 		if (pair->diff.computed)
 			ratio = pair->diff.period_ratio;
@@ -899,8 +901,10 @@ hpp__entry_pair(struct hist_entry *he, struct hist_entry *pair,
 
 	case PERF_HPP_DIFF__WEIGHTED_DIFF:
 		/* No point for wdiff number if we are dummy.. */
-		if (he->dummy)
+		if (he->dummy) {
+			scnprintf(buf, size, "N/A");
 			break;
+		}
 
 		if (pair->diff.computed)
 			wdiff = pair->diff.wdiff;
-- 
2.2.1

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