on 25/11/2012 19:57 Andriy Gapon said the following: > on 24/11/2012 00:17 Alex Chistyakov said the following: >> I collected two samples and put them here: http://1888.spb.ru/samples.zip >> sched-cpu0.ktr is for a VM running on CPU #0 and sched-cpu1.ktr is for >> a VM running on CPU #1 >> They seem to be very different. > > It looks like you didn't stop ktr tracing before running ktrdump or something > like that. schedgraph can not grok the files because it believes that the > timestamps are incorrect. > > # - While the workload is continuing (i.e. before it finishes), disable > # KTR tracing by setting 'sysctl debug.ktr.mask=0'. This is necessary > # to avoid a race condition while running ktrdump, i.e. the KTR ring buffer > # will cycle a bit while ktrdump runs, and this confuses schedgraph because > # the timestamps appear to go backwards at some point.
Hmm, looks like this assessment is not correct. I now think that the root cause of schedgraph issue might be a too wild difference in what TSC counters produce on different (logical/physical) CPUs. E.g.: 131059 1 33232414877586 ... 131058 1 33232414876546 ... 131057 3 33232416064514 ... 131056 3 33232416064198 ... Or even: 131038 0 33232862369416 ... 131037 3 33232409671570 ... 131036 0 33232862367256 ... 131035 3 33232409670982 ... That's 455111586 ticks! > Could you please also provide the CPU identification block from dmesg? This is even more interesting now. -- -- Andriy Gapon _______________________________________________ freebsd-emulation@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-emulation To unsubscribe, send any mail to "freebsd-emulation-unsubscr...@freebsd.org"
