On Fri, Oct 02, 2020 at 10:03:17PM +0900, Namhyung Kim wrote: > Currently perf inject just repipes the event without any flush. It > makes an issue that it changes the order of events processed. > > Normally we want to process events in time order, but events are > recorded from several cpus and they weren't sorted with each other. > So we put them into the ordered event queue, sorted by time, and flush > them when we see a next FINISHED_ROUND event. > > But this is for events from kernel, user space events (like the > FINISHED_ROUND) are processed without queueing. So during the perf > inject, it writes all the FINISHED_ROUND events directly while > SAMPLE (and other) events are kept in the queue. This makes the user > space events are put before any kernel events. > > You can see that with the following command: > > $ perf record -a -o- sleep 1 | perf inject -b | perf script -i- > --show-round-events > PERF_RECORD_FINISHED_ROUND > PERF_RECORD_FINISHED_ROUND > PERF_RECORD_FINISHED_ROUND > ... > > Omitting perf inject, you can see the events are placed in the middle > of the data. > > You might argue that the whole point of the FINISHED_ROUND event is to > sort (kernel) events. And after perf inject, all events are written > in a proper time order so we don't care about the FINISHED_ROUND event > anymore. > > But the problem is we don't know whether the input data is sorted or > not (maybe we can add a feature bit for this?) so it should use an > ordered event queue when processing the input like in perf report.
I like the idea of storing the information that the data is sorted, and when it's there, let's not use ordered_oevets > > Remember all the FINISHED_ROUND events now come before other events so > the tool cannot know when it can flush the data so everything will be > queued until it meets the end of the input. Actually it's same for > perf inject itself as it doesn't flush the queue. > > Below measures time and memory usage during the perf inject and > report using ~190MB data file. > > Before: > perf inject: 11.09 s, 382148 KB > perf report: 8.05 s, 397440 KB > > After: > perf inject: 16.24 s, 83376 KB > perf report: 7.96 s, 216184 KB > > As you can see, it used 2x memory of the input size. I guess it's > because it needs to keep the copy for the whole input. But I don't > understand why processing time of perf inject increased.. would be good to find out first thanks, jirka > > I'm not sure how it affects the auxtrace, but it should be fine IMHO. > > Cc: Al Grant <[email protected]> > Cc: Adrian Hunter <[email protected]> > Signed-off-by: Namhyung Kim <[email protected]> > --- > tools/perf/builtin-inject.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c > index 6d2f410d773a..9fa78a9edfc5 100644 > --- a/tools/perf/builtin-inject.c > +++ b/tools/perf/builtin-inject.c > @@ -79,6 +79,7 @@ static int perf_event__repipe_oe_synth(struct perf_tool > *tool, > union perf_event *event, > struct ordered_events *oe __maybe_unused) > { > + ordered_events__flush(oe, OE_FLUSH__ROUND); > return perf_event__repipe_synth(tool, event); > } > > -- > 2.28.0.806.g8561365e88-goog >
