Peter Zijlstra <[email protected]> writes: > On Tue, May 10, 2016 at 04:18:33PM +0300, Alexander Shishkin wrote: >> When the PMU driver reports a truncated AUX record, it effectively means >> that there is no more usable room in the event's AUX buffer (even though >> there may still be some room, so that perf_aux_output_begin() doesn't take >> action). At this point the consumer still has to be woken up and the event >> has to be disabled, otherwise the event will just keep spinning between >> perf_aux_output_begin() and perf_aux_output_end() until its context gets >> unscheduled. >> >> Again, for cpu-wide events this means never, so once in this condition, >> they will be forever losing data. >> >> Fix this by disabling the event and waking up the consumer in case of a >> truncated AUX record. > >> + if (wakeup) { >> + if (truncated) >> + handle->event->pending_disable = 1; >> + perf_output_wakeup(handle); >> + } > > Does the userspace tool know how to deal with this and re-enable it?
Yes, it knows to ioctl(EVENT_ENABLE). Also, we're already doing the disabling for the no-room-in-buffer condition in perf_aux_output_begin(). Regards, -- Alex
