perf evsel: Modify group pmu name for software events

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 <[email protected]>
Tested-by: Adrian Hunter <[email protected]>
Cc: Ahmad Yasin <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Caleb Biggers <[email protected]>
Cc: Edward Baker <[email protected]>
Cc: Florian Fischer <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Kajol Jain <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Kang Minchul <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Perry Taylor <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ravi Bangoria <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Samantha Alt <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Sumanth Korikkar <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Tiezhu Yang <[email protected]>
Cc: Weilin Wang <[email protected]>
Cc: Xing Zhengjun <[email protected]>
Cc: Yang Jihong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: captain5050

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";