CRAS: Add busyloop event detection in audio_thread

Initialize audio thread monitor in cras_server.
Create a method - check_busyloop for detecting busyloop in audio thread
and take a snapshot for audio thread when busyloop occurs.

BUG=chromium:866240
TEST=audio_thread_unittest

Change-Id: Iab6a05e16e4b17d1b6740e43562bfe8c5d193ec8
Reviewed-on: https://chromium-review.googlesource.com/1148087
Commit-Ready: Chih-Yang Hsia <paulhsia@chromium.org>
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>

3 files changed, 55 insertions, 0 deletions

diff --git a/cras/src/server/audio_thread.c b/cras/src/server/audio_thread.c
index 290bbff2..27f99275 100644
--- a/cras/src/server/audio_thread.c
+++ b/cras/src/server/audio_thread.c
@@ -14,6 +14,7 @@
 #include <syslog.h>
 
 #include "audio_thread_log.h"
+#include "cras_audio_thread_monitor.h"
 #include "cras_config.h"
 #include "cras_fmt_conv.h"
 #include "cras_iodev.h"
@@ -28,6 +29,10 @@
 #define MIN_PROCESS_TIME_US 500 /* 0.5ms - min amount of time to mix/src. */
 #define SLEEP_FUZZ_FRAMES 10 /* # to consider "close enough" to sleep frames. */
 #define MIN_READ_WAIT_US 2000 /* 2ms */
+/*
+ * # to check whether a busyloop event happens
+ */
+#define MAX_CONTINUOUS_ZERO_SLEEP_COUNT 2
 
 /* Messages that can be sent from the main context to the audio thread. */
 enum AUDIO_THREAD_COMMAND {
@@ -861,6 +866,22 @@ static struct pollfd *add_pollfd(struct audio_thread *thread,
 	return &thread->pollfds[thread->num_pollfds - 1];
 }
 
+static int continuous_zero_sleep_count = 0;
+static void check_busyloop(struct timespec* wait_ts)
+{
+	if(wait_ts->tv_sec == 0 && wait_ts->tv_nsec == 0)
+	{
+		continuous_zero_sleep_count ++;
+		if(continuous_zero_sleep_count ==
+		   MAX_CONTINUOUS_ZERO_SLEEP_COUNT)
+			cras_audio_thread_busyloop();
+	}
+	else
+	{
+		continuous_zero_sleep_count = 0;
+	}
+}
+
 /* For playback, fill the audio buffer when needed, for capture, pull out
  * samples when they are ready.
  * This thread will attempt to run at a high priority to allow for low latency
@@ -947,6 +968,8 @@ restart_poll_loop:
 
 		ATLOG(atlog, AUDIO_THREAD_SLEEP, wait_ts ? wait_ts->tv_sec : 0,
 		      wait_ts ? wait_ts->tv_nsec : 0, longest_wake.tv_nsec);
+		if(wait_ts)
+			check_busyloop(wait_ts);
 		rc = ppoll(thread->pollfds, thread->num_pollfds, wait_ts, NULL);
 		clock_gettime(CLOCK_MONOTONIC_RAW, &last_wake);
 		ATLOG(atlog, AUDIO_THREAD_WAKE, rc, 0, 0);
diff --git a/cras/src/server/cras_server.c b/cras/src/server/cras_server.c
index f67ebe13..456fd1c0 100644
--- a/cras/src/server/cras_server.c
+++ b/cras/src/server/cras_server.c
@@ -34,6 +34,7 @@
 #include "cras_telephony.h"
 #endif
 #include "cras_alert.h"
+#include "cras_audio_thread_monitor.h"
 #include "cras_config.h"
 #include "cras_device_monitor.h"
 #include "cras_hotword_handler.h"
@@ -430,6 +431,8 @@ int cras_server_run(unsigned int profile_disable_mask)
 
 	cras_non_empty_audio_handler_init();
 
+	cras_audio_thread_monitor_init();
+
 #ifdef CRAS_DBUS
 	dbus_threads_init_default();
 	dbus_conn = cras_dbus_connect_system_bus();
diff --git a/cras/src/tests/audio_thread_unittest.cc b/cras/src/tests/audio_thread_unittest.cc
index 5da25df6..1dda2e4d 100644
--- a/cras/src/tests/audio_thread_unittest.cc
+++ b/cras/src/tests/audio_thread_unittest.cc
@@ -14,6 +14,7 @@ extern "C" {
 #define BUFFER_SIZE 8192
 #define FIRST_CB_LEVEL 480
 
+static int cras_audio_thread_busyloop_called;
 static unsigned int cras_rstream_dev_offset_called;
 static unsigned int cras_rstream_dev_offset_ret[MAX_CALLS];
 static const struct cras_rstream *cras_rstream_dev_offset_rstream_val[MAX_CALLS];
@@ -690,6 +691,28 @@ TEST(AUdioThreadStreams, DrainStream) {
   EXPECT_EQ(0, thread_drain_stream_ms_remaining(&thread, &rstream));
 }
 
+TEST(BusyloopDetectSuite, CheckerTest) {
+  continuous_zero_sleep_count = 0;
+  cras_audio_thread_busyloop_called = 0;
+  timespec wait_ts;
+  wait_ts.tv_sec = 0;
+  wait_ts.tv_nsec = 0;
+
+  check_busyloop(&wait_ts);
+  EXPECT_EQ(continuous_zero_sleep_count, 1);
+  EXPECT_EQ(cras_audio_thread_busyloop_called, 0);
+  check_busyloop(&wait_ts);
+  EXPECT_EQ(continuous_zero_sleep_count, 2);
+  EXPECT_EQ(cras_audio_thread_busyloop_called, 1);
+  check_busyloop(&wait_ts);
+  EXPECT_EQ(continuous_zero_sleep_count, 3);
+  EXPECT_EQ(cras_audio_thread_busyloop_called, 1);
+
+  wait_ts.tv_sec = 1;
+  check_busyloop(&wait_ts);
+  EXPECT_EQ(continuous_zero_sleep_count, 0);
+  EXPECT_EQ(cras_audio_thread_busyloop_called, 1);
+}
 
 extern "C" {
 
@@ -1129,6 +1152,12 @@ void cras_apm_list_set_aec_dump(struct cras_apm_list *list,
 {
 }
 
+int cras_audio_thread_busyloop()
+{
+  cras_audio_thread_busyloop_called ++;
+  return 0;
+}
+
 }  // extern "C"
 
 int main(int argc, char **argv) {