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Subject: [PATCH v4 06/10] perf stat: implement control commands handling
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <653fe5f3-c986-a841-1ed8-0a7d2fa24c00@linux.intel.com>
Organization: Intel Corp.
Message-ID: <51635bc5-4396-0b87-4150-bc272754af9c@linux.intel.com>
Date:   Mon, 25 May 2020 17:21:15 +0300
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Implement handling of 'enable' and 'disable' control commands
coming from control file descriptor.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 tools/perf/builtin-stat.c | 45 +++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 70b48a279b75..c06c2b701a15 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -439,6 +439,31 @@ static bool process_timeout(bool timeout, unsigned int interval, int *times)
 		return print_interval(interval, times);
 }
 
+static bool process_evlist(struct evlist *evlist, unsigned int interval, int *times)
+{
+	bool stop = false;
+	enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
+
+	if (evlist__ctlfd_process(evlist, &cmd) > 0) {
+		switch (cmd) {
+		case EVLIST_CTL_CMD_ENABLE:
+			pr_info(EVLIST_ENABLED_MSG);
+			stop = print_interval(interval, times);
+			break;
+		case EVLIST_CTL_CMD_DISABLE:
+			stop = print_interval(interval, times);
+			pr_info(EVLIST_DISABLED_MSG);
+			break;
+		case EVLIST_CTL_CMD_ACK:
+		case EVLIST_CTL_CMD_UNSUPPORTED:
+		default:
+			break;
+		}
+	}
+
+	return stop;
+}
+
 static void enable_counters(void)
 {
 	if (stat_config.initial_delay < 0) {
@@ -518,8 +543,8 @@ static int dispatch_events(pid_t pid, struct perf_stat_config *config)
 {
 	pid_t child = 0;
 	bool stop = false;
-	struct timespec time_to_sleep;
-	int sleep_time, status = 0;
+	int time_to_sleep, sleep_time, status = 0;
+	struct timespec time_start, time_stop, time_diff;
 	int times = config->times;
 
 	if (config->interval)
@@ -529,8 +554,7 @@ static int dispatch_events(pid_t pid, struct perf_stat_config *config)
 	else
 		sleep_time = 1000;
 
-	time_to_sleep.tv_sec  = sleep_time / MSEC_PER_SEC;
-	time_to_sleep.tv_nsec = (sleep_time % MSEC_PER_SEC) * NSEC_PER_MSEC;
+	time_to_sleep = sleep_time;
 
 	do {
 		if (pid != -1) {
@@ -543,8 +567,17 @@ static int dispatch_events(pid_t pid, struct perf_stat_config *config)
 		if (child || stop || done)
 			break;
 
-		nanosleep(&time_to_sleep, NULL);
-		stop = process_timeout(config->timeout, config->interval, &times);
+		clock_gettime(CLOCK_MONOTONIC, &time_start);
+		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
+			stop = process_timeout(config->timeout, config->interval, &times);
+			time_to_sleep = sleep_time;
+		} else { /* fd revent */
+			stop = process_evlist(evsel_list, config->interval, &times);
+			clock_gettime(CLOCK_MONOTONIC, &time_stop);
+			diff_timespec(&time_diff, &time_stop, &time_start);
+			time_to_sleep -= time_diff.tv_sec * MSEC_PER_SEC +
+					time_diff.tv_nsec / NSEC_PER_MSEC;
+		}
 	} while (1);
 
 	return status;
-- 
2.24.1