perf metricgroup: Scale the metric result

Some metrics define the scale unit, such as

{
"BriefDescription": "Intel Optane DC persistent memory read latency (ns). Derived from unc_m_pmm_rpq_occupancy.all",
"Counter": "0,1,2,3",
"EventCode": "0xE0",
"EventName": "UNC_M_PMM_READ_LATENCY",
"MetricExpr": "UNC_M_PMM_RPQ_OCCUPANCY.ALL / UNC_M_PMM_RPQ_INSERTS / UNC_M_CLOCKTICKS",
"MetricName": "UNC_M_PMM_READ_LATENCY",
"PerPkg": "1",
"ScaleUnit": "6000000000ns",
"UMask": "0x1",
"Unit": "iMC"
},

For above example, the ratio should be,

ratio = (UNC_M_PMM_RPQ_OCCUPANCY.ALL / UNC_M_PMM_RPQ_INSERTS / UNC_M_CLOCKTICKS) * 6000000000

But in current code, the ratio is not scaled ( * 6000000000)

With this patch, the ratio is scaled and the unit (ns) is printed.

For example,
# 219.4 ns UNC_M_PMM_READ_LATENCY

Signed-off-by: Jin Yao <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/metricgroup.c

···
 	const char **ids;
 	const char *metric_name;
 	const char *metric_expr;
+	const char *metric_unit;
 };
 
 static bool record_evsel(int *ind, struct evsel **start,
···
 		}
 		expr->metric_expr = eg->metric_expr;
 		expr->metric_name = eg->metric_name;
+		expr->metric_unit = eg->metric_unit;
 		expr->metric_events = metric_events;
 		list_add(&expr->nd, &me->head);
 	}
···
 			eg->idnum = idnum;
 			eg->metric_name = pe->metric_name;
 			eg->metric_expr = pe->metric_expr;
+			eg->metric_unit = pe->unit;
 			list_add_tail(&eg->nd, group_list);
 			ret = 0;
 		}

tools/perf/util/metricgroup.h

···
 	struct list_head nd;
 	const char *metric_expr;
 	const char *metric_name;
+	const char *metric_unit;
 	struct evsel **metric_events;
 };
 

tools/perf/util/stat-shadow.c

···
 			   struct evsel **metric_events,
 			   char *name,
 			   const char *metric_name,
+			   const char *metric_unit,
 			   double avg,
 			   int cpu,
 			   struct perf_stat_output_ctx *out,
···
 {
 	print_metric_t print_metric = out->print_metric;
 	struct parse_ctx pctx;
-	double ratio;
+	double ratio, scale;
 	int i;
 	void *ctxp = out->ctx;
 	char *n, *pn;
···
 	for (i = 0; metric_events[i]; i++) {
 		struct saved_value *v;
 		struct stats *stats;
-		double scale;
 
 		if (!strcmp(metric_events[i]->name, "duration_time")) {
 			stats = &walltime_nsecs_stats;
···
 	if (!metric_events[i]) {
 		const char *p = metric_expr;
 
-		if (expr__parse(&ratio, &pctx, &p) == 0)
-			print_metric(config, ctxp, NULL, "%8.1f",
-				metric_name ?
-				metric_name :
-				out->force_header ?  name : "",
-				ratio);
-		else
+		if (expr__parse(&ratio, &pctx, &p) == 0) {
+			char *unit;
+			char metric_bf[64];
+
+			if (metric_unit && metric_name) {
+				if (perf_pmu__convert_scale(metric_unit,
+					&unit, &scale) >= 0) {
+					ratio *= scale;
+				}
+
+				scnprintf(metric_bf, sizeof(metric_bf),
+					  "%s  %s", unit, metric_name);
+				print_metric(config, ctxp, NULL, "%8.1f",
+					     metric_bf, ratio);
+			} else {
+				print_metric(config, ctxp, NULL, "%8.1f",
+					metric_name ?
+					metric_name :
+					out->force_header ?  name : "",
+					ratio);
+			}
+		} else {
 			print_metric(config, ctxp, NULL, NULL,
 				     out->force_header ?
 				     (metric_name ? metric_name : name) : "", 0);
+		}
 	} else
 		print_metric(config, ctxp, NULL, NULL, "", 0);
 
···
 			print_metric(config, ctxp, NULL, NULL, name, 0);
 	} else if (evsel->metric_expr) {
 		generic_metric(config, evsel->metric_expr, evsel->metric_events, evsel->name,
-				evsel->metric_name, avg, cpu, out, st);
+				evsel->metric_name, NULL, avg, cpu, out, st);
 	} else if (runtime_stat_n(st, STAT_NSECS, 0, cpu) != 0) {
 		char unit = 'M';
 		char unit_buf[10];
···
 				out->new_line(config, ctxp);
 			generic_metric(config, mexp->metric_expr, mexp->metric_events,
 					evsel->name, mexp->metric_name,
-					avg, cpu, out, st);
+					mexp->metric_unit, avg, cpu, out, st);
 		}
 	}
 	if (num == 0)