On 06/28/13 22:55, Vince Weaver wrote: > > The perf_event_open() ENABLE/DISABLE/RESET ioctls can take an argument, > PERF_IOC_FLAG_GROUP. This wasn't documented at all until about a year > ago (despite the support being there from the beginning) so I missed > this when initially writing the manpage. > > Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx> Thanks, Vince. Applied. Cheers, Michael > diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 > index 5b8e769..5900b1c 100644 > --- a/man2/perf_event_open.2 > +++ b/man2/perf_event_open.2 > @@ -1664,7 +1664,10 @@ file descriptors > Enables the individual event or event group specified by the > file descriptor argument. > > -The ioctl argument is ignored. > +If the > +.B PERF_IOC_FLAG_GROUP > +bit is set in the ioctl argument then all events in a group are > +enabled, even if the event specified is not the group leader. > .TP > .B PERF_EVENT_IOC_DISABLE > Disables the individual counter or event group specified by the > @@ -1677,7 +1680,10 @@ Enabling or disabling a member of a group other than the leader > affects only that counter; disabling a non-leader > stops that counter from counting but doesn't affect any other counter. > > -The ioctl argument is ignored. > +If the > +.B PERF_IOC_FLAG_GROUP > +bit is set in the ioctl argument then all events in a group are > +disabled, even if the event specified is not the group leader. > .TP > .B PERF_EVENT_IOC_REFRESH > Non-inherited overflow counters can use this > @@ -1702,10 +1708,18 @@ multiplexing > or > .I time_running > values. > -When sent to a group leader, only > -the leader is reset (child events are not). > > -The ioctl argument is ignored. > +If the > +.B PERF_IOC_FLAG_GROUP > +bit is set in the ioctl argument then all events in a group are > +reset, even if the event specified is not the group leader. > + > +If the > +.B PERF_IOC_FLAG_GROUP > +bit is not set then the behavior is somwhat unexpected: > +when sent to a group leader only the leader is reset > +(children are left alone); > +when sent to a child all events in a group are reset. > .TP > .B PERF_EVENT_IOC_PERIOD > IOC_PERIOD is the command to update the period; it > -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
