diff options
Diffstat (limited to '')
| -rw-r--r-- | tools/perf/util/evsel.c | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 6d4a5f6ed75a..fc4faaa7afb9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -404,13 +404,40 @@ const char *perf_evsel__name(struct perf_evsel *evsel) return evsel->name ?: "unknown"; } +/* + * The enable_on_exec/disabled value strategy: + * + * 1) For any type of traced program: + * - all independent events and group leaders are disabled + * - all group members are enabled + * + * Group members are ruled by group leaders. They need to + * be enabled, because the group scheduling relies on that. + * + * 2) For traced programs executed by perf: + * - all independent events and group leaders have + * enable_on_exec set + * - we don't specifically enable or disable any event during + * the record command + * + * Independent events and group leaders are initially disabled + * and get enabled by exec. Group members are ruled by group + * leaders as stated in 1). + * + * 3) For traced programs attached by perf (pid/tid): + * - we specifically enable or disable all events during + * the record command + * + * When attaching events to already running traced we + * enable/disable events specifically, as there's no + * initial traced exec call. + */ void perf_evsel__config(struct perf_evsel *evsel, struct perf_record_opts *opts) { struct perf_event_attr *attr = &evsel->attr; int track = !evsel->idx; /* only the first counter needs these */ - attr->disabled = 1; attr->sample_id_all = opts->sample_id_all_missing ? 0 : 1; attr->inherit = !opts->no_inherit; attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED | @@ -486,6 +513,19 @@ void perf_evsel__config(struct perf_evsel *evsel, attr->mmap = track; attr->comm = track; + /* + * XXX see the function comment above + * + * Disabling only independent events or group leaders, + * keeping group members enabled. + */ + if (!evsel->leader) + attr->disabled = 1; + + /* + * Setting enable_on_exec for independent events and + * group leaders for traced executed by perf. + */ if (perf_target__none(&opts->target) && (!evsel->leader)) attr->enable_on_exec = 1; } |