On 11/15/13 11:08, Vince Weaver wrote: > > This patch attempts to clarify the pid and cpu options to > perf_event_open. > > It does two things: > 1. Tries to make clear that the "pid" argument can mean > process *or* thread. This is made confusing by > how Linux uses the terms mostly interchangably. > 2. The cpu/pid documentation was confusing because of > how the parameters are interdependent. Since there > are only 6 possible combinations I broke out the > possibilities into a table. > > I'm open to comments, especially on how the pid/cpu stuff was broken > out, I'm not sure if I got the style right for that part. I think the structure is okay. I've applied the patch and will tweak the formatting very slightly. Thanks for the patch. Cheers, Michael > Reported-by: Manuel Selva <selva.manuel@xxxxxxxxx> > Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx> > > > > diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 > index 1889689..7d84389 100644 > --- a/man2/perf_event_open.2 > +++ b/man2/perf_event_open.2 > @@ -75,54 +75,36 @@ be accessed via > .BR mmap (2) . > .SS Arguments > .P > -The argument > -.I pid > -allows events to be attached to processes in various ways. > -If > -.I pid > -is 0, measurements happen on the current thread, if > -.I pid > -is greater than 0, the process indicated by > -.I pid > -is measured, and if > -.I pid > -is \-1, all processes are counted. > - > The > -.I cpu > -argument allows measurements to be specific to a CPU. > -If > -.I cpu > -is greater than or equal to 0, > -measurements are restricted to the specified CPU; > -if > -.I cpu > -is \-1, the events are measured on all CPUs. > -.P > -Note that the combination of > -.IR pid " == \-1" > -and > -.IR cpu " == \-1" > -is not valid. > -.P > -A > -.IR pid " > 0" > -and > -.IR cpu " == \-1" > -setting measures per-process and follows that process to whatever CPU the > -process gets scheduled to. > -Per-process events can be created by any user. > -.P > -A > -.IR pid " == \-1" > +.I pid > and > -.IR cpu " >= 0" > -setting is per-CPU and measures all processes on the specified CPU. > -Per-CPU events need the > +.I cpu > +arguments allow specifying which process and CPU to monitor: > +.TP > +.BR pid==0 " and " cpu==\-1 > +This measures the current process/thread on any CPU. > +.TP > +.BR pid==0 " and " cpu>=0 > +This measures the current process/thread only > +when running on the specified CPU. > +.TP > +.BR pid>0 " and " cpu==\-1 > +This measures the specified process/thread on any CPU. > +.TP > +.BR pid>0 " and " cpu>=0 > +This measures the specified process/thread only > +when running on the specified CPU. > +.TP > +.BR pid==\-1 " and " cpu>=0 > +This measures all processes/threads on the specified CPU. > +Measurements such as this require the > .B CAP_SYS_ADMIN > capability or a > .I /proc/sys/kernel/perf_event_paranoid > value of less than 1. > +.TP > +.BR pid==\-1 " and " cpu==\-1 > +This setting is invalid and will return an error. > .P > The > .I group_fd > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ -- 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
