From: Andi Kleen <a...@linux.intel.com>
The multiplexing scaling in perf stat mysteriously adds 0.5 to the
value. This dates back to the original perf tool. Other scaling
code doesn't use that strange convention. Remove the extra 0.5.
Before:
$ perf stat -e 'cycles,cycles,cycles,cycles,cycles,cycles' grep -rq foo
Performance counter stats for 'grep -rq foo':
6,403,580 cycles
(81.62%)
6,404,341 cycles
(81.64%)
6,402,983 cycles
(81.62%)
6,399,941 cycles
(81.63%)
6,399,451 cycles
(81.62%)
6,436,105 cycles
(91.87%)
0.005843799 seconds time elapsed
0.002905000 seconds user
0.002902000 seconds sys
After:
$ ./perf stat -e 'cycles,cycles,cycles,cycles,cycles,cycles' grep -rq foo
Performance counter stats for 'grep -rq foo':
6,422,704 cycles
(81.68%)
6,401,842 cycles
(81.68%)
6,398,432 cycles
(81.68%)
6,397,098 cycles
(81.68%)
6,396,074 cycles
(81.67%)
6,434,980 cycles
(91.62%)
0.005884437 seconds time elapsed
0.003580000 seconds user
0.002356000 seconds sys
Signed-off-by: Andi Kleen <a...@linux.intel.com>
---
tools/perf/util/evsel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 60450087f198..e425f342fe81 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1342,7 +1342,7 @@ void perf_counts_values__scale(struct perf_counts_values
*count,
count->val = 0;
} else if (count->run < count->ena) {
scaled = 1;
- count->val = (u64)((double) count->val * count->ena /
count->run + 0.5);
+ count->val = (u64)((double) count->val * count->ena /
count->run);
}
}
--
2.20.1
