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Subject: [PATCH v5 09/13] 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: <e5cac8dd-7aa4-ec7c-671c-07756907acba@linux.intel.com>
Organization: Intel Corp.
Message-ID: <732e7374-3080-8c8f-eab2-855a2974d695@linux.intel.com>
Date:   Mon, 1 Jun 2020 19:02:22 +0300
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Implement handling of 'enable' and 'disable' control commands
coming from control file descriptor. process_evlist() functions
checks for events on static fd and makes required operations.
If poll event splits initiated timeout interval then the reminder
is calculated and waited in the following poll() syscall.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 tools/perf/builtin-stat.c | 69 +++++++++++++++++++++++++++++----------
 1 file changed, 51 insertions(+), 18 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index d0ddaa5fac96..7fb08454b343 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) {
@@ -514,10 +539,21 @@ static bool is_target_alive(struct target *_target,
 	return false;
 }
 
-static int dispatch_events(pid_t pid, bool timeout, int interval, int *times, struct timespec *ts)
+static int dispatch_events(pid_t pid, bool timeout, int interval, int *times)
 {
 	bool stop = false;
 	int child = 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 (pid != -1)
@@ -528,9 +564,18 @@ static int dispatch_events(pid_t pid, bool timeout, int interval, int *times, st
 		if (done || stop || child)
 			break;
 
-		nanosleep(ts, NULL);
-		stop = process_timeout(timeout, interval, times);
-	}
+		clock_gettime(CLOCK_MONOTONIC, &time_start);
+		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
+			stop = process_timeout(timeout, 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;
+		}
+	} while (1);
 
 	return status;
 }
@@ -598,7 +643,6 @@ 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);
@@ -607,17 +651,6 @@ 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) {
@@ -775,7 +808,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 		enable_counters();
 
 		if (interval || timeout)
-			status = dispatch_events(child_pid, timeout, interval, &times, &ts);
+			status = dispatch_events(child_pid, timeout, interval, &times);
 		if (child_pid != -1) {
 			if (timeout)
 				kill(child_pid, SIGTERM);
@@ -792,7 +825,7 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 			psignal(WTERMSIG(status), argv[0]);
 	} else {
 		enable_counters();
-		dispatch_events(-1, timeout, interval, &times, &ts);
+		dispatch_events(-1, timeout, interval, &times);
 	}
 
 	disable_counters();
-- 
2.24.1