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-rw-r--r--tools/perf/util/evsel.c42
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;
}