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Subject[PATCH 115/161] perf stat: Don't print bogus data on -e cycles
Date
From: Ramkumar Ramachandra <artagnon@gmail.com>

When only the cycles event is requested:

$ perf stat -e cycles dd if=/dev/zero of=/dev/null count=1000000
1000000+0 records in
1000000+0 records out
512000000 bytes (512 MB) copied, 0.26123 s, 2.0 GB/s

Performance counter stats for 'dd if=/dev/zero of=/dev/null count=1000000':

911,626,453 cycles # 0.000 GHz

0.262113350 seconds time elapsed

The 0.000 GHz comment in the output is totally bogus and misleading. It
happens because update_shadow_stats() doesn't touch runtime_nsecs_stats;
it is only written when a requested counter matches a SW_TASK_CLOCK. In
our case, since we have only requested HW_CPU_CYCLES,
runtime_nsecs_stats is unavailable. So, omit printing the comment
altogether.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1380539585-23859-3-git-send-email-artagnon@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-stat.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 700b47849101..ce2266c5cd52 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -997,10 +997,10 @@ static void abs_printout(int cpu, int nr, struct perf_evsel *evsel, double avg)
} else if (perf_evsel__match(evsel, HARDWARE, HW_CPU_CYCLES)) {
total = avg_stats(&runtime_nsecs_stats[cpu]);

- if (total)
- ratio = 1.0 * avg / total;
-
- fprintf(output, " # %8.3f GHz ", ratio);
+ if (total) {
+ ratio = avg / total;
+ fprintf(output, " # %8.3f GHz ", ratio);
+ }
} else if (transaction_run &&
perf_evsel__cmp(evsel, nth_evsel(T_CYCLES_IN_TX))) {
total = avg_stats(&runtime_cycles_stats[cpu]);
--
1.8.1.4


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