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| author | Namhyung Kim <namhyung.kim@lge.com> | 2012-05-31 07:51:45 +0200 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2012-05-31 16:38:42 +0200 |
| commit | a59e64a13a927fb7530bef39e9f5e7de8268137e (patch) | |
| tree | 94cc2528ff263b737a637ad20bc2e1f748fae881 /tools/perf/design.txt | |
| parent | perf tools: Make --version show kernel version instead of pull req tag (diff) | |
| download | linux-a59e64a13a927fb7530bef39e9f5e7de8268137e.tar.xz linux-a59e64a13a927fb7530bef39e9f5e7de8268137e.zip | |
perf tools: Update ioctl documentation for PERF_IOC_FLAG_GROUP
The ioctl interface of perf event fd receives 3 arguments to control
event group behavior but it lacked documentation.
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1338443506-25009-2-git-send-email-namhyung.kim@lge.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/design.txt')
| -rw-r--r-- | tools/perf/design.txt | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/tools/perf/design.txt b/tools/perf/design.txt index bd0bb1b1279b..67e5d0cace85 100644 --- a/tools/perf/design.txt +++ b/tools/perf/design.txt @@ -409,14 +409,15 @@ Counters can be enabled and disabled in two ways: via ioctl and via prctl. When a counter is disabled, it doesn't count or generate events but does continue to exist and maintain its count value. -An individual counter or counter group can be enabled with +An individual counter can be enabled with - ioctl(fd, PERF_EVENT_IOC_ENABLE); + ioctl(fd, PERF_EVENT_IOC_ENABLE, 0); or disabled with - ioctl(fd, PERF_EVENT_IOC_DISABLE); + ioctl(fd, PERF_EVENT_IOC_DISABLE, 0); +For a counter group, pass PERF_IOC_FLAG_GROUP as the third argument. Enabling or disabling the leader of a group enables or disables the whole group; that is, while the group leader is disabled, none of the counters in the group will count. Enabling or disabling a member of a |