> > coming back to this ... > > On 6/12/15 2:39 PM, Liang, Kan wrote: > >>> Yes, perf always can read proc file. The problem is that the proc > >>> file is huge and keep growing faster than proc reader. > >>> So perf top do loop in perf_event__synthesize_mmap_events until > the > >>> test case exit. > >> > >> I'm confused. How are you getting the above time to read /proc maps > >> if it never finishes? > > > > I just tried to simplify the issue for perf record. So you may noticed > > that I only read one thread. There are several threads in the system. > > Also, I do the perf record test when starting the test case. > > The proc file is not that big. > > For perf top, it will monitor whole system. So it never finishes. > > If the proc file is not that big for perf-record why is it a problem for perf- > top? Both should only be reading the maps file for the thread group leader > once and after it is processed getting MMAP events for changes. > Why do you say perf-top can't handle it but perf-record can?
I once wanted to simplify the case. So I limited the perf record for one thread and sampled the test at very beginning. So we can see the processing time. But it makes things more complicate and confusing. :( Anyway, both system-wide-monitorings have this issue. The system-wide monitorings include perf top and perf record -a. Thanks, Kan > > David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
