[PATCH v9 11/15] perf stat: implement control commands handling

[Alexey Budankov]

Implement handling of 'enable' and 'disable' control commands
coming from control file descriptor. process_evlist() function
checks for events on control fds and makes required operations.
If poll event splits initiated timeout interval then the reminder
is calculated and still waited in the following poll() syscall.

Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
---
 tools/perf/builtin-stat.c | 75 ++++++++++++++++++++++++++++-----------
 1 file changed, 55 insertions(+), 20 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 9e4288ecf2b8..5021f7286422 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -485,6 +485,31 @@ static bool handle_interval(unsigned int interval, int *times)
 	return false;
 }
 
+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 = handle_interval(interval, times);
+			break;
+		case EVLIST_CTL_CMD_DISABLE:
+			stop = handle_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) {
@@ -560,10 +585,21 @@ static bool is_target_alive(struct target *_target,
 	return false;
 }
 
-static int dispatch_events(bool forks, int timeout, int interval, int *times, struct timespec *ts)
+static int dispatch_events(bool forks, int timeout, int interval, int *times)
 {
 	bool stop = false;
 	int child_exited = 0, status = 0;
+	int time_to_sleep, sleep_time;
+	struct timespec time_start, time_stop, time_diff;
+
+	if (interval)
+		sleep_time = interval;
+	else if (timeout)
+		sleep_time = timeout;
+	else
+		sleep_time = 1000;
+
+	time_to_sleep = sleep_time;
 
 	while (1) {
 		if (forks)
@@ -574,11 +610,22 @@ static int dispatch_events(bool forks, int timeout, int interval, int *times, st
 		if (done || stop || child_exited)
 			break;
 
-		nanosleep(ts, NULL);
-		if (timeout)
-			stop = true;
-		else
-			stop = handle_interval(interval, times);
+		clock_gettime(CLOCK_MONOTONIC, &time_start);
+		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
+			if (timeout)
+				stop = true;
+			else
+				stop = handle_interval(interval, times);
+			time_to_sleep = sleep_time;
+		} else { /* fd revent */
+			stop = process_evlist(evsel_list, 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;
+			if (time_to_sleep < 0)
+				time_to_sleep = 0;
+		}
 	}
 
 	return status;
@@ -647,7 +694,6 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 	char msg[BUFSIZ];
 	unsigned long long t0, t1;
 	struct evsel *counter;
-	struct timespec ts;
 	size_t l;
 	int status = 0;
 	const bool forks = (argc > 0);
@@ -656,17 +702,6 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 	int i, cpu;
 	bool second_pass = false;
 
-	if (interval) {
-		ts.tv_sec  = interval / USEC_PER_MSEC;
-		ts.tv_nsec = (interval % USEC_PER_MSEC) * NSEC_PER_MSEC;
-	} else if (timeout) {
-		ts.tv_sec  = timeout / USEC_PER_MSEC;
-		ts.tv_nsec = (timeout % USEC_PER_MSEC) * NSEC_PER_MSEC;
-	} else {
-		ts.tv_sec  = 1;
-		ts.tv_nsec = 0;
-	}
-
 	if (forks) {
 		if (perf_evlist__prepare_workload(evsel_list, &target, argv, is_pipe,
 						  workload_exec_failed_signal) < 0) {
@@ -824,7 +859,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 		enable_counters();
 
 		if (interval || timeout)
-			status = dispatch_events(forks, timeout, interval, &times, &ts);
+			status = dispatch_events(forks, timeout, interval, &times);
 		if (child_pid != -1) {
 			if (timeout)
 				kill(child_pid, SIGTERM);
@@ -841,7 +876,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 			psignal(WTERMSIG(status), argv[0]);
 	} else {
 		enable_counters();
-		status = dispatch_events(forks, timeout, interval, &times, &ts);
+		status = dispatch_events(forks, timeout, interval, &times);
 	}
 
 	disable_counters();
-- 
2.24.1