From: Arnaldo Carvalho de Melo <a...@redhat.com> To not sample, what we want are just the PERF_RECORD_ lifetime events for threads, using the default, PERF_TYPE_HARDWARE + PERF_COUNT_HW_CYCLES and freq=1 (the default), makes perf reenable irq_vectors:local_timer_entry, disabling nohz, not good for some use cases where all we want is to get notifications when threads comes and goes...
Fix it by using PERF_TYPE_SOFTWARE (no counter rotation) and PERF_COUNT_SW_DUMMY (created by Adrian so that we could have access to those PERF_RECORD_ goodies). Reported-by: Luiz Fernando Capitulino <lcapitul...@redhat.com> Suggested-by: Peter Zijlstra <pet...@infradead.org> Cc: Adrian Hunter <adrian.hun...@intel.com> Cc: Borislav Petkov <b...@suse.de> Cc: David Ahern <dsah...@gmail.com> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: Jaroslav Skarvada <jskar...@redhat.com> Cc: Jeremy Eder <je...@redhat.com> Cc: Jiri Olsa <jo...@redhat.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Stephane Eranian <eran...@google.com> Link: http://lkml.kernel.org/n/tip-kfsijirfrs6xfhkcdxeoe...@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/python/twatch.py | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/tools/perf/python/twatch.py b/tools/perf/python/twatch.py index 2225162ee1fc..b9d508336ae6 100755 --- a/tools/perf/python/twatch.py +++ b/tools/perf/python/twatch.py @@ -18,10 +18,20 @@ import perf def main(): cpus = perf.cpu_map() threads = perf.thread_map() - evsel = perf.evsel(task = 1, comm = 1, mmap = 0, + evsel = perf.evsel(type = perf.TYPE_SOFTWARE, + config = perf.COUNT_SW_DUMMY, + task = 1, comm = 1, mmap = 0, freq = 0, wakeup_events = 1, watermark = 1, sample_id_all = 1, sample_type = perf.SAMPLE_PERIOD | perf.SAMPLE_TID | perf.SAMPLE_CPU) + + """What we want are just the PERF_RECORD_ lifetime events for threads, + using the default, PERF_TYPE_HARDWARE + PERF_COUNT_HW_CYCLES & freq=1 + (the default), makes perf reenable irq_vectors:local_timer_entry, when + disabling nohz, not good for some use cases where all we want is to get + threads comes and goes... So use (perf.TYPE_SOFTWARE, perf_COUNT_SW_DUMMY, + freq=0) instead.""" + evsel.open(cpus = cpus, threads = threads); evlist = perf.evlist(cpus, threads) evlist.add(evsel) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
