perf-record currently creates events enabled. When doing a system wide collection (-a arg) this causes data collection for perf's initialization activities -- eg., perf_event__synthesize_threads(). For some events (e.g., context switch S/W event or tracepoints like syscalls) perf's initialization causes a lot of events to be captured frequently generating "Check IO/CPU overload!" warnings on larger systems (e.g., 2 socket, quad core, hyperthreading).
perf's initialization phase can be skipped by creating events disabled and then enabling them once the initialization is done. Signed-off-by: David Ahern <[email protected]> --- tools/perf/builtin-record.c | 3 +++ tools/perf/util/evlist.c | 13 +++++++++++++ tools/perf/util/evlist.h | 1 + 3 files changed, 17 insertions(+), 0 deletions(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 6b0519f..f4c3fbe 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -161,6 +161,7 @@ static void config_attr(struct perf_evsel *evsel, struct perf_evlist *evlist) struct perf_event_attr *attr = &evsel->attr; int track = !evsel->idx; /* only the first counter needs these */ + attr->disabled = 1; attr->inherit = !no_inherit; attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED | PERF_FORMAT_TOTAL_TIME_RUNNING | @@ -671,6 +672,8 @@ static int __cmd_record(int argc, const char **argv) } } + perf_evlist__enable(evsel_list); + /* * Let the child rip */ diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index c12bd47..72e9f48 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -113,6 +113,19 @@ void perf_evlist__disable(struct perf_evlist *evlist) } } +void perf_evlist__enable(struct perf_evlist *evlist) +{ + int cpu, thread; + struct perf_evsel *pos; + + for (cpu = 0; cpu < evlist->cpus->nr; cpu++) { + list_for_each_entry(pos, &evlist->entries, node) { + for (thread = 0; thread < evlist->threads->nr; thread++) + ioctl(FD(pos, cpu, thread), PERF_EVENT_IOC_ENABLE); + } + } +} + int perf_evlist__alloc_pollfd(struct perf_evlist *evlist) { int nfds = evlist->cpus->nr * evlist->threads->nr * evlist->nr_entries; diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index ce85ae9..f349150 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -54,6 +54,7 @@ int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite); void perf_evlist__munmap(struct perf_evlist *evlist); void perf_evlist__disable(struct perf_evlist *evlist); +void perf_evlist__enable(struct perf_evlist *evlist); static inline void perf_evlist__set_maps(struct perf_evlist *evlist, struct cpu_map *cpus, -- 1.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
