linux-kernel - Re: perf stat output

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Date:	Sun, 15 Nov 2009 12:05:08 -0200
From:	Lucas De Marchi <lucas.de.marchi@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: perf stat output

Ingo, following the tested patch you asked. It's a bit different of what you
sent because branch-misses is counted in another struct.


Lucas De Marchi

--
commit 70e98c814153f0026a683c5d19674ed8185d02fa
Author: Lucas De Marchi <lucas.de.marchi@...il.com>
Date:   Sun Nov 15 11:20:56 2009 -0200

    Do not print ratio when task-clock event is not counted
    
    The ratio between the number of events and the time elapsed makes sense only
    if task-clock event is counted. Otherwise it will be simply a (confusing)
    
    	#      0.000 M/sec
    
    This patch outputs the ratio only if task-clock event is counted. Some test
    examples of before and after:
    
    Before:
    
    	[lucas@...walker linux.trees.git]$ sudo perf stat -e branch-misses -a -- sleep 1
    
    	 Performance counter stats for 'sleep 1':
    
    		1367818  branch-misses            #      0.000 M/sec
    
    	    1.001494325  seconds time elapsed
    
    After (without task-clock):
    
    	[lucas@...walker perf]$ sudo ./perf stat -e branch-misses -a -- sleep 1
    
    	 Performance counter stats for 'sleep 1':
    
    		1135044  branch-misses
    
    	    1.001370775  seconds time elapsed
    
    After (with task-clock):
    
    	[lucas@...walker perf]$ sudo ./perf stat -e branch-misses -e task-clock -a -- sleep 1
    
    	 Performance counter stats for 'sleep 1':
    
    		1070111  branch-misses            #      0.534 M/sec
    	    2002.730893  task-clock-msecs         #      1.999 CPUs
    
    	    1.001640292  seconds time elapsed
    
    Signed-off-by: Lucas De Marchi <lucas.de.marchi@...il.com>

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index c6df377..c70d720 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -357,7 +357,8 @@ static void abs_printout(int counter, double avg)
 			ratio = avg / total;
 
 		fprintf(stderr, " # %10.3f IPC  ", ratio);
-	} else if (MATCH_EVENT(HARDWARE, HW_BRANCH_MISSES, counter)) {
+	} else if (MATCH_EVENT(HARDWARE, HW_BRANCH_MISSES, counter) &&
+			runtime_branches_stats.n != 0) {
 		total = avg_stats(&runtime_branches_stats);
 
 		if (total)
@@ -365,7 +366,7 @@ static void abs_printout(int counter, double avg)
 
 		fprintf(stderr, " # %10.3f %%    ", ratio);
 
-	} else {
+	} else if (runtime_nsecs_stats.n != 0) {
 		total = avg_stats(&runtime_nsecs_stats);
 
 		if (total)

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