From 05530a7921c0f5149a01e34c4e031c5b18bdc1cc Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Wed, 20 May 2020 11:20:10 -0700 Subject: perf metricgroup: Add options to not group or merge Add --metric-no-group that causes all events within metrics to not be grouped. This can allow the event to get more time when multiplexed, but may also lower accuracy. Add --metric-no-merge option. By default events in different metrics may be shared if the group of events for one metric is the same or larger than that of the second. Sharing may increase or lower accuracy and so is now configurable. Signed-off-by: Ian Rogers Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Andrii Nakryiko Cc: Cong Wang Cc: Jin Yao Cc: John Garry Cc: Kajol Jain Cc: Kan Liang Cc: Kim Phillips Cc: Mark Rutland Cc: Namhyung Kim Cc: Paul Clarke Cc: Peter Zijlstra Cc: Song Liu Cc: Srikar Dronamraju Cc: Stephane Eranian Cc: Vince Weaver Cc: bpf@vger.kernel.org Cc: netdev@vger.kernel.org Link: http://lore.kernel.org/lkml/20200520182011.32236-7-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-stat.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'tools/perf/Documentation') diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt index 77081283856d..498bead1ef3b 100644 --- a/tools/perf/Documentation/perf-stat.txt +++ b/tools/perf/Documentation/perf-stat.txt @@ -236,6 +236,25 @@ filter out the startup phase of the program, which is often very different. Print statistics of transactional execution if supported. +--metric-no-group:: +By default, events to compute a metric are placed in weak groups. The +group tries to enforce scheduling all or none of the events. The +--metric-no-group option places events outside of groups and may +increase the chance of the event being scheduled - leading to more +accuracy. However, as events may not be scheduled together accuracy +for metrics like instructions per cycle can be lower - as both metrics +may no longer be being measured at the same time. + +--metric-no-merge:: +By default metric events in different weak groups can be shared if one +group contains all the events needed by another. In such cases one +group will be eliminated reducing event multiplexing and making it so +that certain groups of metrics sum to 100%. A downside to sharing a +group is that the group may require multiplexing and so accuracy for a +small group that need not have multiplexing is lowered. This option +forbids the event merging logic from sharing events between groups and +may be used to increase accuracy in this case. + STAT RECORD ----------- Stores stat data into perf data file. -- cgit v1.2.3