perf stat: Show percore counts in per CPU output

We have supported the event modifier "percore" which sums up the event
counts for all hardware threads in a core and show the counts per core.

For example,

# perf stat -e cpu/event=cpu-cycles,percore/ -a -A -- sleep 1

Performance counter stats for 'system wide':

S0-D0-C0 395,072 cpu/event=cpu-cycles,percore/
S0-D0-C1 851,248 cpu/event=cpu-cycles,percore/
S0-D0-C2 954,226 cpu/event=cpu-cycles,percore/
S0-D0-C3 1,233,659 cpu/event=cpu-cycles,percore/

This patch provides a new option "--percore-show-thread". It is used
with event modifier "percore" together to sum up the event counts for
all hardware threads in a core but show the counts per hardware thread.

This is essentially a replacement for the any bit (which is gone in
Icelake). Per core counts are useful for some formulas, e.g. CoreIPC.
The original percore version was inconvenient to post process. This
variant matches the output of the any bit.

With this patch, for example,

# perf stat -e cpu/event=cpu-cycles,percore/ -a -A --percore-show-thread -- sleep 1

Performance counter stats for 'system wide':

CPU0 2,453,061 cpu/event=cpu-cycles,percore/
CPU1 1,823,921 cpu/event=cpu-cycles,percore/
CPU2 1,383,166 cpu/event=cpu-cycles,percore/
CPU3 1,102,652 cpu/event=cpu-cycles,percore/
CPU4 2,453,061 cpu/event=cpu-cycles,percore/
CPU5 1,823,921 cpu/event=cpu-cycles,percore/
CPU6 1,383,166 cpu/event=cpu-cycles,percore/
CPU7 1,102,652 cpu/event=cpu-cycles,percore/

We can see counts are duplicated in CPU pairs (CPU0/CPU4, CPU1/CPU5,
CPU2/CPU6, CPU3/CPU7).

The interval mode also works. For example,

# perf stat -e cpu/event=cpu-cycles,percore/ -a -A --percore-show-thread -I 1000
# time CPU counts unit events
1.000425421 CPU0 925,032 cpu/event=cpu-cycles,percore/
1.000425421 CPU1 430,202 cpu/event=cpu-cycles,percore/
1.000425421 CPU2 436,843 cpu/event=cpu-cycles,percore/
1.000425421 CPU3 1,192,504 cpu/event=cpu-cycles,percore/
1.000425421 CPU4 925,032 cpu/event=cpu-cycles,percore/
1.000425421 CPU5 430,202 cpu/event=cpu-cycles,percore/
1.000425421 CPU6 436,843 cpu/event=cpu-cycles,percore/
1.000425421 CPU7 1,192,504 cpu/event=cpu-cycles,percore/

If we offline CPU5, the result is:

# perf stat -e cpu/event=cpu-cycles,percore/ -a -A --percore-show-thread -- sleep 1

Performance counter stats for 'system wide':

CPU0 2,752,148 cpu/event=cpu-cycles,percore/
CPU1 1,009,312 cpu/event=cpu-cycles,percore/
CPU2 2,784,072 cpu/event=cpu-cycles,percore/
CPU3 2,427,922 cpu/event=cpu-cycles,percore/
CPU4 2,752,148 cpu/event=cpu-cycles,percore/
CPU6 2,784,072 cpu/event=cpu-cycles,percore/
CPU7 2,427,922 cpu/event=cpu-cycles,percore/

1.001416041 seconds time elapsed

v4:
---
Ravi Bangoria reports an issue in v3. Once we offline a CPU,
the output is not correct. The issue is we should use the cpu
idx in print_percore_thread rather than using the cpu value.

v3:
---
1. Fix the interval mode output error
2. Use cpu value (not cpu index) in config->aggr_get_id().
3. Refine the code according to Jiri's comments.

v2:
---
Add the explanation in change log. This is essentially a replacement
for the any bit. No code change.

Signed-off-by: Jin Yao <[e-mail]>
Tested-by: Ravi Bangoria <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[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/Documentation/perf-stat.txt

···
 --all-user::
 Configure all used events to run in user space.
 
+--percore-show-thread::
+The event modifier "percore" has supported to sum up the event counts
+for all hardware threads in a core and show the counts per core.
+
+This option with event modifier "percore" enabled also sums up the event
+counts for all hardware threads in a core but show the sum counts per
+hardware thread. This is essentially a replacement for the any bit and
+convenient for post processing.
+
 EXAMPLES
 --------
 

tools/perf/builtin-stat.c

···
 	OPT_BOOLEAN_FLAG(0, "all-user", &stat_config.all_user,
 			 "Configure all used events to run in user space.",
 			 PARSE_OPT_EXCLUSIVE),
+	OPT_BOOLEAN(0, "percore-show-thread", &stat_config.percore_show_thread,
+		    "Use with 'percore' event qualifier to show the event "
+		    "counts of one hardware thread by sum up total hardware "
+		    "threads of same physical core"),
 	OPT_END()
 };
 

tools/perf/util/stat-display.c

···
 			config->csv_sep);
 			break;
 	case AGGR_NONE:
-		if (evsel->percore) {
+		if (evsel->percore && !config->percore_show_thread) {
 			fprintf(config->output, "S%d-D%d-C%*d%s",
 				cpu_map__id_to_socket(id),
 				cpu_map__id_to_die(id),
···
 static void print_counter_aggrdata(struct perf_stat_config *config,
 				   struct evsel *counter, int s,
 				   char *prefix, bool metric_only,
-				   bool *first)
+				   bool *first, int cpu)
 {
 	struct aggr_data ad;
 	FILE *output = config->output;
···
 		fprintf(output, "%s", prefix);
 
 	uval = val * counter->scale;
-	printout(config, id, nr, counter, uval, prefix,
+	printout(config, cpu != -1 ? cpu : id, nr, counter, uval, prefix,
 		 run, ena, 1.0, &rt_stat);
 	if (!metric_only)
 		fputc('\n', output);
···
 		evlist__for_each_entry(evlist, counter) {
 			print_counter_aggrdata(config, counter, s,
 					       prefix, metric_only,
-					       &first);
+					       &first, -1);
 		}
 		if (metric_only)
 			fputc('\n', output);
···
 			"the same PMU. Try reorganizing the group.\n");
 }
 
+static void print_percore_thread(struct perf_stat_config *config,
+				 struct evsel *counter, char *prefix)
+{
+	int s, s2, id;
+	bool first = true;
+
+	for (int i = 0; i < perf_evsel__nr_cpus(counter); i++) {
+		s2 = config->aggr_get_id(config, evsel__cpus(counter), i);
+		for (s = 0; s < config->aggr_map->nr; s++) {
+			id = config->aggr_map->map[s];
+			if (s2 == id)
+				break;
+		}
+
+		print_counter_aggrdata(config, counter, s,
+				       prefix, false,
+				       &first, i);
+	}
+}
+
 static void print_percore(struct perf_stat_config *config,
 			  struct evsel *counter, char *prefix)
 {
···
 	if (!(config->aggr_map || config->aggr_get_id))
 		return;
 
+	if (config->percore_show_thread)
+		return print_percore_thread(config, counter, prefix);
+
 	for (s = 0; s < config->aggr_map->nr; s++) {
 		if (prefix && metric_only)
 			fprintf(output, "%s", prefix);
 
 		print_counter_aggrdata(config, counter, s,
 				       prefix, metric_only,
-				       &first);
+				       &first, -1);
 	}
 
 	if (metric_only)

tools/perf/util/stat.h

···
 	bool			 walltime_run_table;
 	bool			 all_kernel;
 	bool			 all_user;
+	bool			 percore_show_thread;
 	FILE			*output;
 	unsigned int		 interval;
 	unsigned int		 timeout;