On 29.10.2013 02:33, Vince Weaver wrote: > > The PERF_EVENT_IOC_PERIOD ioctl was broken until 2.6.36, and it turns out > that the ARM architecture has some differing behavior too. Applied. Thanks, Michael > Reported-by: Andreas Sandberg <andreas.sandberg@xxxxxxxx> > Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx> > > diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 > index f4cb5bd..f337a27 100644 > --- a/man2/perf_event_open.2 > +++ b/man2/perf_event_open.2 > @@ -1976,11 +1976,17 @@ reset, even if the event specified is not the group leader > (but see BUGS). > .TP > .B PERF_EVENT_IOC_PERIOD > -IOC_PERIOD is the command to update the period; it > -does not update the current period but instead defers until next. > +This updates the overflow period for the event. > +On most architectures the new period does not take effect until > +after the next overflow happens; > +on ARM since Linux 3.7 the period is updated immediately. > > The argument is a pointer to a 64-bit value containing the > desired new period. > + > +Prior to Linux 2.6.36 this ioctl always failed due to a bug > +in the kernel. > + > .TP > .B PERF_EVENT_IOC_SET_OUTPUT > This tells the kernel to report event notifications to the specified > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ My next Linux/UNIX system programming course: -- 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
