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Subject: [PATCH v12 11/15] 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: <8d91c3a0-3db4-0a7a-ae13-299adb444bd6@linux.intel.com>
Organization: Intel Corp.
Message-ID: <3cb8a826-145f-81f4-fcb2-fa20045c6957@linux.intel.com>
Date:   Fri, 17 Jul 2020 10:05:06 +0300
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Implement handling of 'enable' and 'disable' control commands coming
from control file descriptor. If poll event splits initiated timeout
interval then the reminder is calculated and still waited in the
following evlist__poll() call.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/builtin-stat.c | 83 ++++++++++++++++++++++++++++++---------
 1 file changed, 65 insertions(+), 18 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 9d5c503e698f..5280a45af5dc 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -560,9 +560,61 @@ 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 void process_evlist(struct evlist *evlist, unsigned int interval)
+{
+	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);
+			if (interval)
+				process_interval();
+			break;
+		case EVLIST_CTL_CMD_DISABLE:
+			if (interval)
+				process_interval();
+			pr_info(EVLIST_DISABLED_MSG);
+			break;
+		case EVLIST_CTL_CMD_ACK:
+		case EVLIST_CTL_CMD_UNSUPPORTED:
+		default:
+			break;
+		}
+	}
+}
+
+static void compute_tts(struct timespec *time_start, struct timespec *time_stop,
+			int *time_to_sleep)
+{
+	int tts = *time_to_sleep;
+	struct timespec time_diff;
+
+	diff_timespec(&time_diff, time_stop, time_start);
+
+	tts -= time_diff.tv_sec * MSEC_PER_SEC +
+	       time_diff.tv_nsec / NSEC_PER_MSEC;
+
+	if (tts < 0)
+		tts = 0;
+
+	*time_to_sleep = tts;
+}
+
+static int dispatch_events(bool forks, int timeout, int interval, int *times)
 {
 	int child_exited = 0, status = 0;
+	int time_to_sleep, sleep_time;
+	struct timespec time_start, time_stop;
+
+	if (interval)
+		sleep_time = interval;
+	else if (timeout)
+		sleep_time = timeout;
+	else
+		sleep_time = 1000;
+
+	time_to_sleep = sleep_time;
 
 	while (!done) {
 		if (forks)
@@ -573,9 +625,16 @@ static int dispatch_events(bool forks, int timeout, int interval, int *times, st
 		if (child_exited)
 			break;
 
-		nanosleep(ts, NULL);
-		if (timeout || handle_interval(interval, times))
-			break;
+		clock_gettime(CLOCK_MONOTONIC, &time_start);
+		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
+			if (timeout || handle_interval(interval, times))
+				break;
+			time_to_sleep = sleep_time;
+		} else { /* fd revent */
+			process_evlist(evsel_list, interval);
+			clock_gettime(CLOCK_MONOTONIC, &time_stop);
+			compute_tts(&time_start, &time_stop, &time_to_sleep);
+		}
 	}
 
 	return status;
@@ -644,7 +703,6 @@ 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);
@@ -653,17 +711,6 @@ 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) {
@@ -821,7 +868,7 @@ 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);
@@ -838,7 +885,7 @@ 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