Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a59e64a1 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarNamhyung 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent aa5cdd30

tools/perf/design.txt

+4 −3
Original line number Diff line number Diff line
@@ -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