[PATCH v4 19/44] perf evsel: Modify group pmu name for software events

[Ian Rogers <irogers@google.com>]

If we have a group of {cycles,faults} then we need the faults software
event to appear to be on the same PMU as cycles so that we don't split
the group in parse_events__sort_events_and_fix_groups. This case is
relatively easy as cycles is the leader and will have a PMU name. In
the reverse case, {faults,cycles} we still need faults to appear to
have the PMU name of cycles but the old behavior is just to return
"cpu". For hybrid this fails as cycles will be on "cpu_core" or
"cpu_atom", causing faults to be split into a different group.

Change the behavior for software events so that the whole group is
searched for the named PMU.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/evsel.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1cd04b5998d2..63522322e118 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -829,23 +829,26 @@ bool evsel__name_is(struct evsel *evsel, const char *name)
 
 const char *evsel__group_pmu_name(const struct evsel *evsel)
 {
-	const struct evsel *leader;
+	struct evsel *leader, *pos;
 
 	/* If the pmu_name is set use it. pmu_name isn't set for CPU and software events. */
 	if (evsel->pmu_name)
 		return evsel->pmu_name;
 	/*
 	 * Software events may be in a group with other uncore PMU events. Use
-	 * the pmu_name of the group leader to avoid breaking the software event
-	 * out of the group.
+	 * the pmu_name of the first non-software event to avoid breaking the
+	 * software event out of the group.
 	 *
 	 * Aux event leaders, like intel_pt, expect a group with events from
 	 * other PMUs, so substitute the AUX event's PMU in this case.
 	 */
 	leader  = evsel__leader(evsel);
-	if ((evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) &&
-	    leader->pmu_name) {
-		return leader->pmu_name;
+	if (evsel->core.attr.type == PERF_TYPE_SOFTWARE || evsel__is_aux_event(leader)) {
+		/* Starting with the leader, find the first event with a named PMU. */
+		for_each_group_evsel(pos, leader) {
+			if (pos->pmu_name)
+				return pos->pmu_name;
+		}
 	}
 
 	return "cpu";
-- 
2.40.1.495.gc816e09b53d-goog