Re: [PATCH 1/2] perf_event_open.2: Document PERF_EVENT_IOC_PAUSE_OUTPUT
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From: Michael Kerrisk (man-pages) <hidden>
Date: 2016-10-22 10:03:02
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Hello Wang Nan Thanks for this patch! A few comments below. On 10/21/2016 01:38 PM, Wang Nan wrote:
quoted hunk ↗ jump to hunk
Linux 4.7 (86e7972f690c1017fd086cdfe53d8524e68c661c) introduces PERF_EVENT_IOC_PAUSE_OUTPUT feature. Document it. Signed-off-by: Wang Nan <redacted> Cc: Michael Kerrisk <redacted> --- man2/perf_event_open.2 | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index fade28c..2d3acad 100644 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2@@ -2865,7 +2865,18 @@ The argument is a BPF program file descriptor that was created by a previous .BR bpf (2) system call. -.SS Using prctl(2) +.TP +.BR PERF_EVENT_IOC_PAUSE_OUTPUT " (since Linux 4.7)" +.\" commit 86e7972f690c1017fd086cdfe53d8524e68c661c +This allows pausing and resuming the event's ring-buffer. A +paused ring-buffer does not prevent samples generation, but simply
s/samples generation/generation of samples/
+discards them. The discarded samples are considered lost, causes
s/them/the samples/ s/causes/causing/
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+.BR PERF_RECORD_LOST +to be generated when possible. + +The argument is an integer. Nonzero value pauses the ring-buffer,
s/Nonzero/a nonzero/
+zero value resumes the ring-buffer.
s/zero value/zero/
+.SS Using prctl
As noted by Vince, the change to this SS line should not be part of this patch.
A process can enable or disable all the event groups that are attached to it using the .BR prctl (2)
Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html