On Mon, 9 Jul 2018 16:53:52 +0200 Claudio <claudio.font...@gliwa.com> wrote:
> > One additional data point, based on brute force again: > > I applied this change, in order to understand if it was the > > trace_event_raw_event_* (I suppose primarily trace_event_raw_event_switch) > > that contained the latency "offenders": > > diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h > index 4ecdfe2..969467d 100644 > --- a/include/trace/trace_events.h > +++ b/include/trace/trace_events.h > @@ -704,6 +704,8 @@ trace_event_raw_event_##call(void *__data, proto) > > struct trace_event_raw_##call *entry; \ > int __data_size; \ > \ > + return; \ > + \ > if (trace_trigger_soft_disabled(trace_file)) \ > return; \ > \ > > > This reduces the latency overhead to 6% down from 25%. > > Maybe obvious? Wanted to share in case it helps, and will dig further. I noticed that just disabling tracing "echo 0 > tracing_on" is very similar. I'm now recording timings of various parts of the code. But at most I've seen is a 12us, which should not add the overhead. So it's triggering something else. I'll be going on PTO next week, and there's things I must do this week, thus I may not have much more time to look into this until I get back from PTO (July 23rd). -- Steve
