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| author | Jin Yao <yao.jin@linux.intel.com> | 2019-01-04 14:10:30 +0800 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-01-04 12:54:49 -0300 |
| commit | a3366db06bb656cef2e03f30f780d93059bcc594 (patch) | |
| tree | 9e1c2d5c7448f8fa37a429ed8c2f5da7c20c3356 /tools/perf/util/machine.c | |
| parent | 86c22ab7227f59169f64275875c97ef495668b77 (diff) | |
perf report: Fix wrong iteration count in --branch-history
By calculating the removed loops, we can get the iteration count.
But the iteration count could be reported incorrectly, reporting
impossibly high counts.
That's because previous code uses the number of removed LBR entries for
the iteration count. That's not good. Fix this by increasing the
iteration count when a loop is detected.
When matching the chain, the iteration count would be added up, finally we need
to compute the average value when printing out.
For example,
$ perf report --branch-history --stdio --no-children
Before:
---f2 +0
|
|--33.62%--f1 +9 (cycles:1)
| f1 +0
| main +22 (cycles:1)
| main +17
| main +38 (cycles:1)
| main +27
| f1 +26 (cycles:1)
| f1 +24
| f2 +27 (cycles:7)
| f2 +0
| f1 +19 (cycles:1)
| f1 +14
| f2 +27 (cycles:11)
| f2 +0
| f1 +9 (cycles:1 iter:2968 avg_cycles:3)
| f1 +0
| main +22 (cycles:1 iter:2968 avg_cycles:3)
| main +17
| main +38 (cycles:1 iter:2968 avg_cycles:3)
2968 is an impossible high iteration count and avg_cycles is too small.
After:
---f2 +0
|
|--33.62%--f1 +9 (cycles:1)
| f1 +0
| main +22 (cycles:1)
| main +17
| main +38 (cycles:1)
| main +27
| f1 +26 (cycles:1)
| f1 +24
| f2 +27 (cycles:7)
| f2 +0
| f1 +19 (cycles:1)
| f1 +14
| f2 +27 (cycles:11)
| f2 +0
| f1 +9 (cycles:1 iter:1 avg_cycles:23)
| f1 +0
| main +22 (cycles:1 iter:1 avg_cycles:23)
| main +17
| main +38 (cycles:1 iter:1 avg_cycles:23)
avg_cycles:23 is the average cycles of this iteration.
Fixes: c4ee06251d42 ("perf report: Calculate the average cycles of iterations")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1546582230-17507-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/machine.c')
| -rw-r--r-- | tools/perf/util/machine.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 6fcb3bce0442..143f7057d581 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -2005,7 +2005,7 @@ static void save_iterations(struct iterations *iter, { int i; - iter->nr_loop_iter = nr; + iter->nr_loop_iter++; iter->cycles = 0; for (i = 0; i < nr; i++) |