* perf_event_open() - add PERF_IOC_FLAG_GROUP documentation
@ 2013-06-28 20:55 Vince Weaver
[not found] ` <alpine.DEB.2.10.1306281651100.10799-6xBS8L8d439fDsnSvq7Uq4Se7xf15W0s1dQoKJhdanU@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Vince Weaver @ 2013-06-28 20:55 UTC (permalink / raw)
To: Michael Kerrisk; +Cc: linux-man-u79uwXL29TY76Z2rM5mHXA
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-e7X0jjDqjFGHXe+LvDLADg@public.gmane.org>
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
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: perf_event_open() - add PERF_IOC_FLAG_GROUP documentation
[not found] ` <alpine.DEB.2.10.1306281651100.10799-6xBS8L8d439fDsnSvq7Uq4Se7xf15W0s1dQoKJhdanU@public.gmane.org>
@ 2013-07-02 4:09 ` Michael Kerrisk
[not found] ` <51D2525F.7070900-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Michael Kerrisk @ 2013-07-02 4:09 UTC (permalink / raw)
To: Vince Weaver; +Cc: Michael Kerrisk, linux-man-u79uwXL29TY76Z2rM5mHXA
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-e7X0jjDqjFGHXe+LvDLADg@public.gmane.org>
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
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: perf_event_open() - add PERF_IOC_FLAG_GROUP documentation
[not found] ` <51D2525F.7070900-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
@ 2013-07-02 13:55 ` Vince Weaver
0 siblings, 0 replies; 3+ messages in thread
From: Vince Weaver @ 2013-07-02 13:55 UTC (permalink / raw)
To: Michael Kerrisk; +Cc: linux-man-u79uwXL29TY76Z2rM5mHXA
On Tue, 2 Jul 2013, Michael Kerrisk wrote:
> 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-e7X0jjDqjFGHXe+LvDLADg@public.gmane.org>
>
> Thanks, Vince. Applied.
Just noticed the following typos in that patch; sorry for not catching
these before sending out the original.
Signed-off-by: Vince Weaver <vincent.weaver-e7X0jjDqjFGHXe+LvDLADg@public.gmane.org>
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index 862913b..dc04232 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -1588,7 +1588,7 @@ is the amount of data actually dumped (can be less than
.I weight
If
.B PERF_SAMPLE_WEIGHT
-is enabled, then a 64 bit value provided by the hardwre
+is enabled, then a 64 bit value provided by the hardware
is recorded that indicates how costly the event was.
This allows expensive events to stand out more clearly
in profiles.
@@ -1837,7 +1837,7 @@ Using an argument of 0 is considered undefined behavior.
.TP
.B PERF_EVENT_IOC_RESET
Reset the event count specified by the
-file descriptor argumentto zero.
+file descriptor argument to zero.
This resets only the counts; there is no way to reset the
multiplexing
.I time_enabled
@@ -1852,7 +1852,7 @@ 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:
+bit is not set, then the behavior is somewhat 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.
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2013-06-28 20:55 perf_event_open() - add PERF_IOC_FLAG_GROUP documentation Vince Weaver
[not found] ` <alpine.DEB.2.10.1306281651100.10799-6xBS8L8d439fDsnSvq7Uq4Se7xf15W0s1dQoKJhdanU@public.gmane.org>
2013-07-02 4:09 ` Michael Kerrisk
[not found] ` <51D2525F.7070900-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-07-02 13:55 ` Vince Weaver
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