* [patch] perf_event_open.2 clarify the PERF_FLAG_FD_* flags
@ 2015-01-08 17:04 ` Vince Weaver
0 siblings, 0 replies; 4+ messages in thread
From: Vince Weaver @ 2015-01-08 17:04 UTC (permalink / raw)
Cc: xmtk.manpages, linux-man, linux-kernel, Peter Zijlstra,
Paul Mackerras, Ingo Molnar, Arnaldo Carvalho de Melo
This change clarifies the behavior of the PERF_FLAG_FD_OUTPUT and
PERF_FLAG_FD_NO_GROUP flags to perf_event_open(), and removes
the related FIXME comments.
While writing tests to validate the behavior of these flags I
discovered that PERF_FLAG_FD_OUTPUT has been broken since the
2.6.35 kernel release.
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index 8bde791..7181c29 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -149,14 +149,17 @@ then
.BR execve (2).
.TP
.BR PERF_FLAG_FD_NO_GROUP
-.\" FIXME . The following sentence is unclear
-This flag allows creating an event as part of an event group but
-having no group leader.
-It is unclear why this is useful.
-.\" FIXME . So, why is it useful?
-.TP
-.BR PERF_FLAG_FD_OUTPUT
-This flag reroutes the output from an event to the group leader.
+This flag tells the event to ignore the
+.IR group_fd
+parameter except for the purpose of setting up output redirection
+using the
+.B PERF_FLAG_FD_OUTPUT
+flag.
+.TP
+.BR PERF_FLAG_FD_OUTPUT " (broken since Linux 2.6.35)."
+This flag re-routes the event's sampled output to instead
+be included in the mmap buffer of the event specified by
+.IR group_fd .
.TP
.BR PERF_FLAG_PID_CGROUP " (since Linux 2.6.39)."
This flag activates per-container system-wide monitoring.
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [patch] perf_event_open.2 clarify the PERF_FLAG_FD_* flags
@ 2015-01-08 17:04 ` Vince Weaver
0 siblings, 0 replies; 4+ messages in thread
From: Vince Weaver @ 2015-01-08 17:04 UTC (permalink / raw)
To: Michael Kerrisk (man-pages)
Cc: xmtk.manpages, linux-man, linux-kernel, Peter Zijlstra,
Paul Mackerras, Ingo Molnar, Arnaldo Carvalho de Melo
This change clarifies the behavior of the PERF_FLAG_FD_OUTPUT and
PERF_FLAG_FD_NO_GROUP flags to perf_event_open(), and removes
the related FIXME comments.
While writing tests to validate the behavior of these flags I
discovered that PERF_FLAG_FD_OUTPUT has been broken since the
2.6.35 kernel release.
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index 8bde791..7181c29 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -149,14 +149,17 @@ then
.BR execve (2).
.TP
.BR PERF_FLAG_FD_NO_GROUP
-.\" FIXME . The following sentence is unclear
-This flag allows creating an event as part of an event group but
-having no group leader.
-It is unclear why this is useful.
-.\" FIXME . So, why is it useful?
-.TP
-.BR PERF_FLAG_FD_OUTPUT
-This flag reroutes the output from an event to the group leader.
+This flag tells the event to ignore the
+.IR group_fd
+parameter except for the purpose of setting up output redirection
+using the
+.B PERF_FLAG_FD_OUTPUT
+flag.
+.TP
+.BR PERF_FLAG_FD_OUTPUT " (broken since Linux 2.6.35)."
+This flag re-routes the event's sampled output to instead
+be included in the mmap buffer of the event specified by
+.IR group_fd .
.TP
.BR PERF_FLAG_PID_CGROUP " (since Linux 2.6.39)."
This flag activates per-container system-wide monitoring.
^ permalink raw reply related [flat|nested] 4+ messages in thread
[parent not found: <alpine.DEB.2.11.1501081201020.25399-6xBS8L8d439fDsnSvq7Uqyn2WXadKZNJe7X0jjDqjFGHXe+LvDLADg@public.gmane.org>]
* Re: [patch] perf_event_open.2 clarify the PERF_FLAG_FD_* flags
2015-01-08 17:04 ` Vince Weaver
@ 2015-01-09 13:15 ` Michael Kerrisk (man-pages)
-1 siblings, 0 replies; 4+ messages in thread
From: Michael Kerrisk (man-pages) @ 2015-01-09 13:15 UTC (permalink / raw)
To: Vince Weaver
Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
xmtk.manpages-Re5JQEeQqe8AvxtiuMwx3w,
linux-man-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA, Peter Zijlstra,
Paul Mackerras, Ingo Molnar, Arnaldo Carvalho de Melo
Hi Vince,
On 01/08/2015 06:04 PM, Vince Weaver wrote:
>
> This change clarifies the behavior of the PERF_FLAG_FD_OUTPUT and
> PERF_FLAG_FD_NO_GROUP flags to perf_event_open(), and removes
> the related FIXME comments.
Patch applied. Thank you!
> While writing tests to validate the behavior of these flags I
> discovered that PERF_FLAG_FD_OUTPUT has been broken since the
> 2.6.35 kernel release.
Sigh!
Cheers,
Michael
> 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 8bde791..7181c29 100644
> --- a/man2/perf_event_open.2
> +++ b/man2/perf_event_open.2
> @@ -149,14 +149,17 @@ then
> .BR execve (2).
> .TP
> .BR PERF_FLAG_FD_NO_GROUP
> -.\" FIXME . The following sentence is unclear
> -This flag allows creating an event as part of an event group but
> -having no group leader.
> -It is unclear why this is useful.
> -.\" FIXME . So, why is it useful?
> -.TP
> -.BR PERF_FLAG_FD_OUTPUT
> -This flag reroutes the output from an event to the group leader.
> +This flag tells the event to ignore the
> +.IR group_fd
> +parameter except for the purpose of setting up output redirection
> +using the
> +.B PERF_FLAG_FD_OUTPUT
> +flag.
> +.TP
> +.BR PERF_FLAG_FD_OUTPUT " (broken since Linux 2.6.35)."
> +This flag re-routes the event's sampled output to instead
> +be included in the mmap buffer of the event specified by
> +.IR group_fd .
> .TP
> .BR PERF_FLAG_PID_CGROUP " (since Linux 2.6.39)."
> This flag activates per-container system-wide monitoring.
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [patch] perf_event_open.2 clarify the PERF_FLAG_FD_* flags
@ 2015-01-09 13:15 ` Michael Kerrisk (man-pages)
0 siblings, 0 replies; 4+ messages in thread
From: Michael Kerrisk (man-pages) @ 2015-01-09 13:15 UTC (permalink / raw)
To: Vince Weaver
Cc: mtk.manpages, xmtk.manpages, linux-man, linux-kernel,
Peter Zijlstra, Paul Mackerras, Ingo Molnar,
Arnaldo Carvalho de Melo
Hi Vince,
On 01/08/2015 06:04 PM, Vince Weaver wrote:
>
> This change clarifies the behavior of the PERF_FLAG_FD_OUTPUT and
> PERF_FLAG_FD_NO_GROUP flags to perf_event_open(), and removes
> the related FIXME comments.
Patch applied. Thank you!
> While writing tests to validate the behavior of these flags I
> discovered that PERF_FLAG_FD_OUTPUT has been broken since the
> 2.6.35 kernel release.
Sigh!
Cheers,
Michael
> Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
>
> diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
> index 8bde791..7181c29 100644
> --- a/man2/perf_event_open.2
> +++ b/man2/perf_event_open.2
> @@ -149,14 +149,17 @@ then
> .BR execve (2).
> .TP
> .BR PERF_FLAG_FD_NO_GROUP
> -.\" FIXME . The following sentence is unclear
> -This flag allows creating an event as part of an event group but
> -having no group leader.
> -It is unclear why this is useful.
> -.\" FIXME . So, why is it useful?
> -.TP
> -.BR PERF_FLAG_FD_OUTPUT
> -This flag reroutes the output from an event to the group leader.
> +This flag tells the event to ignore the
> +.IR group_fd
> +parameter except for the purpose of setting up output redirection
> +using the
> +.B PERF_FLAG_FD_OUTPUT
> +flag.
> +.TP
> +.BR PERF_FLAG_FD_OUTPUT " (broken since Linux 2.6.35)."
> +This flag re-routes the event's sampled output to instead
> +be included in the mmap buffer of the event specified by
> +.IR group_fd .
> .TP
> .BR PERF_FLAG_PID_CGROUP " (since Linux 2.6.39)."
> This flag activates per-container system-wide monitoring.
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
^ permalink raw reply [flat|nested] 4+ messages in thread
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2015-01-08 17:04 [patch] perf_event_open.2 clarify the PERF_FLAG_FD_* flags Vince Weaver
2015-01-08 17:04 ` Vince Weaver
[not found] ` <alpine.DEB.2.11.1501081201020.25399-6xBS8L8d439fDsnSvq7Uqyn2WXadKZNJe7X0jjDqjFGHXe+LvDLADg@public.gmane.org>
2015-01-09 13:15 ` Michael Kerrisk (man-pages)
2015-01-09 13:15 ` Michael Kerrisk (man-pages)
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