[PATCH v2 2/2] perf stat: Add support to print counts after a period of time

[ufo19890607 <ufo19890607@gmail.com>]

From: yuzhoujian <yuzhoujian@didichuxing.com>

Introduce a new option to print counts after N milliseconds
and update perf-stat documentation accordingly.

Show below is the output of the new option for perf stat.

        $ perf stat --time 2000 -e cycles -a
        Performance counter stats for 'system wide':

                157,260,423      cycles

                2.003060766 seconds time elapsed

We can print the count deltas after N milliseconds with this new
introduced option. This option is not supported with "-I" option.

Changes since v1:
- none.

Signed-off-by: yuzhoujian <yuzhoujian@didichuxing.com>
---
 tools/perf/Documentation/perf-stat.txt |  7 ++++++-
 tools/perf/builtin-stat.c              | 29 ++++++++++++++++++++++++++---
 tools/perf/util/stat.h                 |  1 +
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 47a21645f60c..8270a0708ea2 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -149,7 +149,12 @@ The overhead percentage could be high in some cases, for instance with small, su
 --interval-count times::
 Print count deltas for fixed number of times.
 This option should be used together with "-I" option.
-	example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
+	example: 'perf stat -I 1000 --times-print 2 -e cycles -a'
+
+--time msecs::
+Print count deltas after N milliseconds (minimum: 10 ms).
+This option is not supported with "-I" option.
+	example: 'perf stat --time 2000 -e cycles -a'
 
 --metric-only::
 Only print computed metrics. Print them in a single line.
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 406f546ad74c..427f06dc35cc 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -573,6 +573,7 @@ static int __run_perf_stat(int argc, const char **argv)
 {
 	int interval = stat_config.interval;
 	int times = stat_config.times;
+	int time = stat_config.time;
 	char msg[BUFSIZ];
 	unsigned long long t0, t1;
 	struct perf_evsel *counter;
@@ -586,6 +587,9 @@ static int __run_perf_stat(int argc, const char **argv)
 	if (interval) {
 		ts.tv_sec  = interval / USEC_PER_MSEC;
 		ts.tv_nsec = (interval % USEC_PER_MSEC) * NSEC_PER_MSEC;
+	} else if (time) {
+		ts.tv_sec  = time / USEC_PER_MSEC;
+		ts.tv_nsec = (time % USEC_PER_MSEC) * NSEC_PER_MSEC;
 	} else {
 		ts.tv_sec  = 1;
 		ts.tv_nsec = 0;
@@ -698,9 +702,11 @@ static int __run_perf_stat(int argc, const char **argv)
 		perf_evlist__start_workload(evsel_list);
 		enable_counters();
 
-		if (interval) {
+		if (interval || time) {
 			while (!waitpid(child_pid, &status, WNOHANG)) {
 				nanosleep(&ts, NULL);
+				if (time)
+					break;
 				process_interval();
 				if (interval_count == true) {
 					if (--times == 0)
@@ -722,7 +728,9 @@ static int __run_perf_stat(int argc, const char **argv)
 		enable_counters();
 		while (!done) {
 			nanosleep(&ts, NULL);
-			if (interval) {
+			if (interval || time) {
+				if (time)
+					break;
 				process_interval();
 				if (interval_count == true) {
 					if (--times == 0)
@@ -1904,6 +1912,8 @@ static const struct option stat_options[] = {
 		    "print counts at regular interval in ms (>= 10)"),
 	OPT_INTEGER(0, "interval-count", &stat_config.times,
 		    "print counts for fixed number of times"),
+	OPT_UINTEGER(0, "time", &stat_config.time,
+		    "print counts after a period of time in ms (>= 10)"),
 	OPT_SET_UINT(0, "per-socket", &stat_config.aggr_mode,
 		     "aggregate counts per processor socket", AGGR_SOCKET),
 	OPT_SET_UINT(0, "per-core", &stat_config.aggr_mode,
@@ -2701,7 +2711,7 @@ int cmd_stat(int argc, const char **argv)
 	int status = -EINVAL, run_idx;
 	const char *mode;
 	FILE *output = stderr;
-	unsigned int interval;
+	unsigned int interval, time;
 	int times;
 	const char * const stat_subcommands[] = { "record", "report" };
 
@@ -2734,6 +2744,7 @@ int cmd_stat(int argc, const char **argv)
 
 	interval = stat_config.interval;
 	times = stat_config.times;
+	time = stat_config.time;
 
 	/*
 	 * For record command the -o is already taken care of.
@@ -2885,6 +2896,7 @@ int cmd_stat(int argc, const char **argv)
 				   "The overhead percentage could be high in some cases. "
 				   "Please proceed with caution.\n");
 	}
+
 	if (times && interval)
 		interval_count = true;
 	else if (times && !interval) {
@@ -2895,6 +2907,17 @@ int cmd_stat(int argc, const char **argv)
 		goto out;
 	}
 
+	if (time && time < 10) {
+		pr_err("time must be >= 10ms.\n");
+		parse_options_usage(stat_usage, stat_options, "time", 0);
+		goto out;
+	} else if (time && interval) {
+		pr_err("time option is not supported with interval-print.\n");
+		parse_options_usage(stat_usage, stat_options, "time", 0);
+		parse_options_usage(stat_usage, stat_options, "I", 1);
+		goto out;
+	}
+
 	if (perf_evlist__alloc_stats(evsel_list, interval))
 		goto out;
 
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index b2f8a347d358..6c621951fda8 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -90,6 +90,7 @@ struct perf_stat_config {
 	bool		scale;
 	FILE		*output;
 	unsigned int	interval;
+	unsigned int	time;
 	int				times;
 	struct runtime_stat *stats;
 	int		stats_num;
-- 
2.14.1