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Subject: [PATCH v3 5/9] perf stat: implement control commands handling
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
To:     Arnaldo Carvalho de Melo <acme@redhat.com>
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: <eb38e9e5-754f-d410-1d9b-e26b702d51b7@linux.intel.com>
Organization: Intel Corp.
Message-ID: <078a7905-f029-88c4-9bd5-1c6a394d3e82@linux.intel.com>
Date:   Wed, 13 May 2020 11:02:15 +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 | 48 +++++++++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 73404b723592..abea82a1ba24 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -460,8 +460,9 @@ static int handle_events(pid_t pid, struct perf_stat_config *config)
 {
 	pid_t child = 0;
 	bool res, stop = false;
-	struct timespec time_to_sleep;
-	int sleep_time, status = 0, times = config->times;
+	int time_to_sleep, sleep_time, status = 0, times = config->times;
+	enum evlist_ctl_cmd cmd = EVLIST_CTL_CMD_UNSUPPORTED;
+	struct timespec time_start, time_stop, time_diff;
 
 	if (config->interval)
 		sleep_time = config->interval;
@@ -470,22 +471,45 @@ static int handle_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)
 			child = waitpid(pid, &status, WNOHANG);
 		if (child || stop || done)
 			break;
-		nanosleep(&time_to_sleep, NULL);
-		if (pid == -1)
-			stop = !is_target_alive(&target, evsel_list->core.threads);
-		if (config->timeout) {
-			stop = !stop ? true : stop;
-		} else {
-			res = print_interval_and_stop(config, &times);
-			stop = !stop ? res : stop;
+		clock_gettime(CLOCK_MONOTONIC, &time_start);
+		if (!(evlist__poll(evsel_list, time_to_sleep) > 0)) { /* poll timeout or EINTR */
+			if (pid == -1)
+				stop = !is_target_alive(&target, evsel_list->core.threads);
+			if (config->timeout) {
+				stop = !stop ? true : stop;
+			} else {
+				res = print_interval_and_stop(config, &times);
+				stop = !stop ? res : stop;
+			}
+			time_to_sleep = sleep_time;
+		} else { /* fd revent */
+			if (evlist__ctlfd_process(evsel_list, &cmd) > 0) {
+				switch (cmd) {
+				case EVLIST_CTL_CMD_ENABLE:
+					pr_info(EVLIST_ENABLED_MSG);
+					stop = print_interval_and_stop(config, &times);
+					break;
+				case EVLIST_CTL_CMD_DISABLE:
+					stop = print_interval_and_stop(config, &times);
+					pr_info(EVLIST_DISABLED_MSG);
+					break;
+				case EVLIST_CTL_CMD_ACK:
+				case EVLIST_CTL_CMD_UNSUPPORTED:
+				default:
+					break;
+				}
+			}
+			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);
 
-- 
2.24.1