perf metrics: Compute unmerged uncore metrics individually

When merging counts from multiple uncore PMUs the metric is only
computed for the metric leader. When merging/aggregation is disabled,
prior to this patch just the leader's metric would be computed. Fix
this by computing the metric for each PMU.

On a SkylakeX:
Before:
```
$ perf stat -A -M memory_bandwidth_total -a sleep 1

 Performance counter stats for 'system wide':

CPU0               82,217      UNC_M_CAS_COUNT.RD [uncore_imc_0] #      9.2 MB/s  memory_bandwidth_total
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_0] #      0.0 MB/s  memory_bandwidth_total
CPU0               61,395      UNC_M_CAS_COUNT.WR [uncore_imc_0]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_0]
CPU0                    0      UNC_M_CAS_COUNT.RD [uncore_imc_1]
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_1]
CPU0                    0      UNC_M_CAS_COUNT.WR [uncore_imc_1]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_1]
CPU0               81,570      UNC_M_CAS_COUNT.RD [uncore_imc_2]
CPU18             113,886      UNC_M_CAS_COUNT.RD [uncore_imc_2]
CPU0               62,330      UNC_M_CAS_COUNT.WR [uncore_imc_2]
CPU18              66,942      UNC_M_CAS_COUNT.WR [uncore_imc_2]
CPU0               75,489      UNC_M_CAS_COUNT.RD [uncore_imc_3]
CPU18              27,958      UNC_M_CAS_COUNT.RD [uncore_imc_3]
CPU0               55,864      UNC_M_CAS_COUNT.WR [uncore_imc_3]
CPU18              38,727      UNC_M_CAS_COUNT.WR [uncore_imc_3]
CPU0                    0      UNC_M_CAS_COUNT.RD [uncore_imc_4]
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_4]
CPU0                    0      UNC_M_CAS_COUNT.WR [uncore_imc_4]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_4]
CPU0               75,423      UNC_M_CAS_COUNT.RD [uncore_imc_5]
CPU18             104,527      UNC_M_CAS_COUNT.RD [uncore_imc_5]
CPU0               57,596      UNC_M_CAS_COUNT.WR [uncore_imc_5]
CPU18              56,777      UNC_M_CAS_COUNT.WR [uncore_imc_5]
CPU0        1,003,440,851 ns   duration_time

       1.003440851 seconds time elapsed
```

After:
```
$ perf stat -A -M memory_bandwidth_total -a sleep 1

 Performance counter stats for 'system wide':

CPU0               88,968      UNC_M_CAS_COUNT.RD [uncore_imc_0] #      9.5 MB/s  memory_bandwidth_total
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_0] #      0.0 MB/s  memory_bandwidth_total
CPU0               59,498      UNC_M_CAS_COUNT.WR [uncore_imc_0]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_0]
CPU0                    0      UNC_M_CAS_COUNT.RD [uncore_imc_1] #      0.0 MB/s  memory_bandwidth_total
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_1] #      0.0 MB/s  memory_bandwidth_total
CPU0                    0      UNC_M_CAS_COUNT.WR [uncore_imc_1]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_1]
CPU0               88,635      UNC_M_CAS_COUNT.RD [uncore_imc_2] #      9.5 MB/s  memory_bandwidth_total
CPU18             117,975      UNC_M_CAS_COUNT.RD [uncore_imc_2] #     11.5 MB/s  memory_bandwidth_total
CPU0               60,829      UNC_M_CAS_COUNT.WR [uncore_imc_2]
CPU18              62,105      UNC_M_CAS_COUNT.WR [uncore_imc_2]
CPU0               82,238      UNC_M_CAS_COUNT.RD [uncore_imc_3] #      8.7 MB/s  memory_bandwidth_total
CPU18              22,906      UNC_M_CAS_COUNT.RD [uncore_imc_3] #      3.6 MB/s  memory_bandwidth_total
CPU0               53,959      UNC_M_CAS_COUNT.WR [uncore_imc_3]
CPU18              32,990      UNC_M_CAS_COUNT.WR [uncore_imc_3]
CPU0                    0      UNC_M_CAS_COUNT.RD [uncore_imc_4] #      0.0 MB/s  memory_bandwidth_total
CPU18                   0      UNC_M_CAS_COUNT.RD [uncore_imc_4] #      0.0 MB/s  memory_bandwidth_total
CPU0                    0      UNC_M_CAS_COUNT.WR [uncore_imc_4]
CPU18                   0      UNC_M_CAS_COUNT.WR [uncore_imc_4]
CPU0               83,595      UNC_M_CAS_COUNT.RD [uncore_imc_5] #      8.9 MB/s  memory_bandwidth_total
CPU18             110,151      UNC_M_CAS_COUNT.RD [uncore_imc_5] #     10.5 MB/s  memory_bandwidth_total
CPU0               56,540      UNC_M_CAS_COUNT.WR [uncore_imc_5]
CPU18              53,816      UNC_M_CAS_COUNT.WR [uncore_imc_5]
CPU0        1,003,353,416 ns   duration_time
```

Signed-off-by: Ian Rogers <irogers@google.com>                                  |
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Kaige Ye <ye@kaige.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: John Garry <john.g.garry@oracle.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240221070754.4163916-2-irogers@google.com

tools/perf/util/metricgroup.c

@@ -44,6 +44,8 @@ struct metric_event *metricgroup__lookup(struct rblist *metric_events,
 	if (!metric_events)
 		return NULL;
 
+	if (evsel->metric_leader)
+		me.evsel = evsel->metric_leader;
 	nd = rblist__find(metric_events, &me);
 	if (nd)
 		return container_of(nd, struct metric_event, nd);

tools/perf/util/stat-shadow.c

@@ -356,6 +356,7 @@ static void print_nsecs(struct perf_stat_config *config,
 }
 
 static int prepare_metric(const struct metric_expr *mexp,
+			  const struct evsel *evsel,
 			  struct expr_parse_ctx *pctx,
 			  int aggr_idx)
 {
@@ -399,8 +400,29 @@ static int prepare_metric(const struct metric_expr *mexp,
 			source_count = 1;
 		} else {
 			struct perf_stat_evsel *ps = metric_events[i]->stats;
-			struct perf_stat_aggr *aggr = &ps->aggr[aggr_idx];
+			struct perf_stat_aggr *aggr;
 
+			/*
+			 * If there are multiple uncore PMUs and we're not
+			 * reading the leader's stats, determine the stats for
+			 * the appropriate uncore PMU.
+			 */
+			if (evsel && evsel->metric_leader &&
+			    evsel->pmu != evsel->metric_leader->pmu &&
+			    mexp->metric_events[i]->pmu == evsel->metric_leader->pmu) {
+				struct evsel *pos;
+
+				evlist__for_each_entry(evsel->evlist, pos) {
+					if (pos->pmu != evsel->pmu)
+						continue;
+					if (pos->metric_leader != mexp->metric_events[i])
+						continue;
+					ps = pos->stats;
+					source_count = 1;
+					break;
+				}
+			}
+			aggr = &ps->aggr[aggr_idx];
 			if (!aggr)
 				break;
 
@@ -416,7 +438,8 @@ static int prepare_metric(const struct metric_expr *mexp,
 				source_count = 0;
 			} else {
 				val = aggr->counts.val;
-				source_count = evsel__source_count(metric_events[i]);
+				if (!source_count)
+					source_count = evsel__source_count(metric_events[i]);
 			}
 		}
 		n = strdup(evsel__metric_id(metric_events[i]));
@@ -463,7 +486,7 @@ static void generic_metric(struct perf_stat_config *config,
 		pctx->sctx.user_requested_cpu_list = strdup(config->user_requested_cpu_list);
 	pctx->sctx.runtime = runtime;
 	pctx->sctx.system_wide = config->system_wide;
-	i = prepare_metric(mexp, pctx, aggr_idx);
+	i = prepare_metric(mexp, evsel, pctx, aggr_idx);
 	if (i < 0) {
 		expr__ctx_free(pctx);
 		return;
@@ -524,7 +547,7 @@ double test_generic_metric(struct metric_expr *mexp, int aggr_idx)
 	if (!pctx)
 		return NAN;
 
-	if (prepare_metric(mexp, pctx, aggr_idx) < 0)
+	if (prepare_metric(mexp, /*evsel=*/NULL, pctx, aggr_idx) < 0)
 		goto out;
 
 	if (expr__parse(&ratio, pctx, mexp->metric_expr))