perf metricgroup: Remove duped metric group events

A metric group contains multiple metrics. These metrics may use the same
events. If metrics use separate events then it leads to more
multiplexing and overall metric counts fail to sum to 100%.

Modify how metrics are associated with events so that if the events in
an earlier group satisfy the current metric, the same events are used.
A record of used events is kept and at the end of processing unnecessary
events are eliminated.

Before:

  $ perf stat -a -M TopDownL1 sleep 1

   Performance counter stats for 'system wide':

       920,211,343   uops_issued.any             #      0.5 Backend_Bound   (16.56%)
     1,977,733,128   idq_uops_not_delivered.core                            (16.56%)
        51,668,510   int_misc.recovery_cycles                               (16.56%)
       732,305,692   uops_retired.retire_slots                              (16.56%)
     1,497,621,849   cycles                                                 (16.56%)
       721,098,274   uops_issued.any             #      0.1 Bad_Speculation (16.79%)
     1,332,681,791   cycles                                                 (16.79%)
       552,475,482   uops_retired.retire_slots                              (16.79%)
        47,708,340   int_misc.recovery_cycles                               (16.79%)
     1,383,713,292   cycles
                                                 #      0.4 Frontend_Bound  (16.76%)
     2,013,757,701   idq_uops_not_delivered.core                            (16.76%)
     1,373,363,790   cycles
                                                 #      0.1 Retiring        (33.54%)
       577,302,589   uops_retired.retire_slots                              (33.54%)
       392,766,987   inst_retired.any            #      0.3 IPC             (50.24%)
     1,351,873,350   cpu_clk_unhalted.thread                                (50.24%)
     1,332,510,318   cycles
                                                 # 5330041272.0 SLOTS       (49.90%)

       1.006336145 seconds time elapsed

After:

  $ perf stat -a -M TopDownL1 sleep 1

   Performance counter stats for 'system wide':

       765,949,145   uops_issued.any             #      0.1 Bad_Speculation
                                                 #      0.5 Backend_Bound   (50.09%)
     1,883,830,591   idq_uops_not_delivered.core #      0.3 Frontend_Bound  (50.09%)
        48,237,080   int_misc.recovery_cycles                               (50.09%)
       581,798,385   uops_retired.retire_slots   #      0.1 Retiring        (50.09%)
     1,361,628,527   cycles
                                                 # 5446514108.0 SLOTS       (50.09%)
       391,415,714   inst_retired.any            #      0.3 IPC             (49.91%)
     1,336,486,781   cpu_clk_unhalted.thread                                (49.91%)

       1.005469298 seconds time elapsed

Note: Bad_Speculation + Backend_Bound + Frontend_Bound + Retiring = 100%
after, where as before it is 110%. After there are 2 groups, whereas
before there are 6. After the cycles event appears once, before it
appeared 5 times.
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200520182011.32236-6-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/metricgroup.c

@@ -93,36 +93,72 @@ struct egroup {
 	bool has_constraint;
 };
 
+/**
+ * Find a group of events in perf_evlist that correpond to those from a parsed
+ * metric expression.
+ * @perf_evlist: a list of events something like: {metric1 leader, metric1
+ * sibling, metric1 sibling}:W,duration_time,{metric2 leader, metric2 sibling,
+ * metric2 sibling}:W,duration_time
+ * @pctx: the parse context for the metric expression.
+ * @has_constraint: is there a contraint on the group of events? In which case
+ * the events won't be grouped.
+ * @metric_events: out argument, null terminated array of evsel's associated
+ * with the metric.
+ * @evlist_used: in/out argument, bitmap tracking which evlist events are used.
+ * @return the first metric event or NULL on failure.
+ */
 static struct evsel *find_evsel_group(struct evlist *perf_evlist,
 				      struct expr_parse_ctx *pctx,
+				      bool has_constraint,
 				      struct evsel **metric_events,
 				      unsigned long *evlist_used)
 {
-	struct evsel *ev;
-	bool leader_found;
-	const size_t idnum = hashmap__size(&pctx->ids);
-	size_t i = 0;
-	int j = 0;
+	struct evsel *ev, *current_leader = NULL;
 	double *val_ptr;
+	int i = 0, matched_events = 0, events_to_match;
+	const int idnum = (int)hashmap__size(&pctx->ids);
+
+	/* duration_time is grouped separately. */
+	if (!has_constraint &&
+	    hashmap__find(&pctx->ids, "duration_time", (void **)&val_ptr))
+		events_to_match = idnum - 1;
+	else
+		events_to_match = idnum;
 
 	evlist__for_each_entry (perf_evlist, ev) {
-		if (test_bit(j++, evlist_used))
+		/*
+		 * Events with a constraint aren't grouped and match the first
+		 * events available.
+		 */
+		if (has_constraint && ev->weak_group)
 			continue;
-		if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr)) {
-			if (!metric_events[i])
-				metric_events[i] = ev;
-			i++;
-			if (i == idnum)
-				break;
-		} else {
-			/* Discard the whole match and start again */
-			i = 0;
+		if (!has_constraint && ev->leader != current_leader) {
+			/*
+			 * Start of a new group, discard the whole match and
+			 * start again.
+			 */
+			matched_events = 0;
 			memset(metric_events, 0,
 				sizeof(struct evsel *) * idnum);
+			current_leader = ev->leader;
 		}
+		if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr))
+			metric_events[matched_events++] = ev;
+		if (matched_events == events_to_match)
+			break;
 	}
 
-	if (i != idnum) {
+	if (events_to_match != idnum) {
+		/* Add the first duration_time. */
+		evlist__for_each_entry(perf_evlist, ev) {
+			if (!strcmp(ev->name, "duration_time")) {
+				metric_events[matched_events++] = ev;
+				break;
+			}
+		}
+	}
+
+	if (matched_events != idnum) {
 		/* Not whole match */
 		return NULL;
 	}
@@ -130,18 +166,8 @@ static struct evsel *find_evsel_group(struct evlist *perf_evlist,
 	metric_events[idnum] = NULL;
 
 	for (i = 0; i < idnum; i++) {
-		leader_found = false;
-		evlist__for_each_entry(perf_evlist, ev) {
-			if (!leader_found && (ev == metric_events[i]))
-				leader_found = true;
-
-			if (leader_found &&
-			    !strcmp(ev->name, metric_events[i]->name)) {
-				ev->metric_leader = metric_events[i];
-			}
-			j++;
-		}
 		ev = metric_events[i];
+		ev->metric_leader = ev;
 		set_bit(ev->idx, evlist_used);
 	}
 
@@ -157,7 +183,7 @@ static int metricgroup__setup_events(struct list_head *groups,
 	int i = 0;
 	int ret = 0;
 	struct egroup *eg;
-	struct evsel *evsel;
+	struct evsel *evsel, *tmp;
 	unsigned long *evlist_used;
 
 	evlist_used = bitmap_alloc(perf_evlist->core.nr_entries);
@@ -173,7 +199,8 @@ static int metricgroup__setup_events(struct list_head *groups,
 			ret = -ENOMEM;
 			break;
 		}
-		evsel = find_evsel_group(perf_evlist, &eg->pctx, metric_events,
+		evsel = find_evsel_group(perf_evlist, &eg->pctx,
+					eg->has_constraint, metric_events,
 					evlist_used);
 		if (!evsel) {
 			pr_debug("Cannot resolve %s: %s\n",
@@ -203,6 +230,12 @@ static int metricgroup__setup_events(struct list_head *groups,
 		list_add(&expr->nd, &me->head);
 	}
 
+	evlist__for_each_entry_safe(perf_evlist, tmp, evsel) {
+		if (!test_bit(evsel->idx, evlist_used)) {
+			evlist__remove(perf_evlist, evsel);
+			evsel__delete(evsel);
+		}
+	}
 	bitmap_free(evlist_used);
 
 	return ret;