| Message ID | 1477049893-143199-1-git-send-email-wangnan0@huawei.com |
|---|---|
| State | New |
| Headers | show |
On Fri, 21 Oct 2016, Wang Nan wrote: > -.SS Using prctl(2) > +.SS Using prctl why this change? > +.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 > +discards them. The discarded samples are considered lost, causes > +.BR PERF_RECORD_LOST > +to be generated when possible. I don't know if it's worth mentioning that the reason to add this is to allow reading the ring-buffer without having to worry about data being overwritten. There are a few odd wording choices (mostly plural nouns) but otherwise looks fine to me. Reviewed-by: Vince Weaver <vincent.weaver@maine.edu>
On 10/21/2016 11:16 PM, Vince Weaver wrote: > On Fri, 21 Oct 2016, Wang Nan wrote: > > >> -.SS Using prctl(2) >> +.SS Using prctl > > why this change? I suspect a diff against a slight stale version of the page, since I added the '(2)' just a few days ago. Wang Nan, please do pull the latest version of the page :-). >> +.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 >> +discards them. The discarded samples are considered lost, causes >> +.BR PERF_RECORD_LOST >> +to be generated when possible. > > I don't know if it's worth mentioning that the reason to add this is to > allow reading the ring-buffer without having to worry about data being > overwritten. Wang Nan, what do you you thing. Should this be added? > There are a few odd wording choices (mostly plural nouns) but otherwise > looks fine to me. > > Reviewed-by: Vince Weaver <vincent.weaver@maine.edu> Wang Nan, I'll send a few wording corrections. Could you please include Vince's reviewed by tag on your next revision? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
Hello Wang Nan Thanks for this patch! A few comments below. On 10/21/2016 01:38 PM, Wang Nan wrote: > Linux 4.7 (86e7972f690c1017fd086cdfe53d8524e68c661c) introduces > PERF_EVENT_IOC_PAUSE_OUTPUT feature. Document it. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > Cc: Michael Kerrisk <mtk.manpages@gmail.com> > --- > 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/ > +.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/
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 +discards them. The discarded samples are considered lost, causes +.BR PERF_RECORD_LOST +to be generated when possible. + +The argument is an integer. Nonzero value pauses the ring-buffer, +zero value resumes the ring-buffer. +.SS Using prctl A process can enable or disable all the event groups that are attached to it using the .BR prctl (2)
Linux 4.7 (86e7972f690c1017fd086cdfe53d8524e68c661c) introduces PERF_EVENT_IOC_PAUSE_OUTPUT feature. Document it. Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> --- man2/perf_event_open.2 | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) -- 2.10.1