perf stat: Turn off summary for interval mode by default

There's a risk that outputting interval mode summaries by default breaks
CSV consumers. It already broke pmu-tools/toplev.

So now we turn off the summary by default but we create a new option
'--summary' to enable the summary. This is active even when not using
CSV mode.

Before:

root@kbl-ppc:~# perf stat -I1000 --interval-count 2
# time counts unit events
1.000265904 8,005.73 msec cpu-clock # 8.006 CPUs utilized
1.000265904 601 context-switches # 0.075 K/sec
1.000265904 10 cpu-migrations # 0.001 K/sec
1.000265904 0 page-faults # 0.000 K/sec
1.000265904 66,746,521 cycles # 0.008 GHz
1.000265904 71,874,398 instructions # 1.08 insn per cycle
1.000265904 13,356,781 branches # 1.668 M/sec
1.000265904 298,756 branch-misses # 2.24% of all branches
2.001857667 8,012.52 msec cpu-clock # 8.013 CPUs utilized
2.001857667 164 context-switches # 0.020 K/sec
2.001857667 10 cpu-migrations # 0.001 K/sec
2.001857667 2 page-faults # 0.000 K/sec
2.001857667 5,822,188 cycles # 0.001 GHz
2.001857667 2,186,170 instructions # 0.38 insn per cycle
2.001857667 442,378 branches # 0.055 M/sec
2.001857667 44,750 branch-misses # 10.12% of all branches

Performance counter stats for 'system wide':

16,018.25 msec cpu-clock # 7.993 CPUs utilized
765 context-switches # 0.048 K/sec
20 cpu-migrations # 0.001 K/sec
2 page-faults # 0.000 K/sec
72,568,709 cycles # 0.005 GHz
74,060,568 instructions # 1.02 insn per cycle
13,799,159 branches # 0.861 M/sec
343,506 branch-misses # 2.49% of all branches

2.004118489 seconds time elapsed

After:

root@kbl-ppc:~# perf stat -I1000 --interval-count 2
# time counts unit events
1.001336393 8,013.28 msec cpu-clock # 8.013 CPUs utilized
1.001336393 82 context-switches # 0.010 K/sec
1.001336393 8 cpu-migrations # 0.001 K/sec
1.001336393 0 page-faults # 0.000 K/sec
1.001336393 4,199,121 cycles # 0.001 GHz
1.001336393 1,373,991 instructions # 0.33 insn per cycle
1.001336393 270,681 branches # 0.034 M/sec
1.001336393 31,659 branch-misses # 11.70% of all branches
2.003905006 8,020.52 msec cpu-clock # 8.021 CPUs utilized
2.003905006 184 context-switches # 0.023 K/sec
2.003905006 8 cpu-migrations # 0.001 K/sec
2.003905006 2 page-faults # 0.000 K/sec
2.003905006 5,446,190 cycles # 0.001 GHz
2.003905006 2,312,547 instructions # 0.42 insn per cycle
2.003905006 451,691 branches # 0.056 M/sec
2.003905006 37,925 branch-misses # 8.40% of all branches

root@kbl-ppc:~# perf stat -I1000 --interval-count 2 --summary
# time counts unit events
1.001313128 8,013.20 msec cpu-clock # 8.013 CPUs utilized
1.001313128 83 context-switches # 0.010 K/sec
1.001313128 8 cpu-migrations # 0.001 K/sec
1.001313128 0 page-faults # 0.000 K/sec
1.001313128 4,470,950 cycles # 0.001 GHz
1.001313128 1,440,045 instructions # 0.32 insn per cycle
1.001313128 283,222 branches # 0.035 M/sec
1.001313128 33,576 branch-misses # 11.86% of all branches
2.003857385 8,020.34 msec cpu-clock # 8.020 CPUs utilized
2.003857385 154 context-switches # 0.019 K/sec
2.003857385 8 cpu-migrations # 0.001 K/sec
2.003857385 2 page-faults # 0.000 K/sec
2.003857385 4,515,676 cycles # 0.001 GHz
2.003857385 2,180,449 instructions # 0.48 insn per cycle
2.003857385 435,254 branches # 0.054 M/sec
2.003857385 31,179 branch-misses # 7.16% of all branches

Performance counter stats for 'system wide':

16,033.53 msec cpu-clock # 7.992 CPUs utilized
237 context-switches # 0.015 K/sec
16 cpu-migrations # 0.001 K/sec
2 page-faults # 0.000 K/sec
8,986,626 cycles # 0.001 GHz
3,620,494 instructions # 0.40 insn per cycle
718,476 branches # 0.045 M/sec
64,755 branch-misses # 9.01% of all branches

2.006124542 seconds time elapsed

Fixes: c7e5b328a8d4 ("perf stat: Report summary for interval mode")
Signed-off-by: Jin Yao <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[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/Documentation/perf-stat.txt

···
 hardware thread. This is essentially a replacement for the any bit and
 convenient for post processing.
 
+--summary::
+Print summary for interval mode (-I).
+
 EXAMPLES
 --------
 

tools/perf/builtin-stat.c

···
 {
 	struct evsel *counter;
 
-	if (!stat_config.summary && (read_affinity_counters(rs) < 0))
+	if (!stat_config.stop_read_counter && (read_affinity_counters(rs) < 0))
 		return;
 
 	evlist__for_each_entry(evsel_list, counter) {
···
 	if (stat_config.walltime_run_table)
 		stat_config.walltime_run[run_idx] = t1 - t0;
 
-	if (interval) {
+	if (interval && stat_config.summary) {
 		stat_config.interval = 0;
-		stat_config.summary = true;
+		stat_config.stop_read_counter = true;
 		init_stats(&walltime_nsecs_stats);
 		update_stats(&walltime_nsecs_stats, t1 - t0);
 
···
 		    "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_BOOLEAN(0, "summary", &stat_config.summary,
+		       "print summary for interval mode"),
 #ifdef HAVE_LIBPFM
 	OPT_CALLBACK(0, "pfm-events", &evsel_list, "event",
 		"libpfm4 event selector. use 'perf list' to list available events",

tools/perf/util/stat.h

···
 	bool			 summary;
 	bool			 metric_no_group;
 	bool			 metric_no_merge;
+	bool			 stop_read_counter;
 	FILE			*output;
 	unsigned int		 interval;
 	unsigned int		 timeout;