Tune SensorService thread priority, lower sensor event latency (f71fcf96) · Commits · e / os / android_frameworks_native-old

services/sensorservice/SensorService.cpp

+14 −0

Original line number	Diff line number	Diff line
		@@ -47,6 +47,7 @@

		#include <inttypes.h>
		#include <math.h>
		#include <sched.h>
		#include <stdint.h>
		#include <sys/socket.h>
		#include <sys/stat.h>
		@@ -71,6 +72,7 @@ bool SensorService::sHmacGlobalKeyIsValid = false;

		#define SENSOR_SERVICE_DIR "/data/system/sensor_service"
		#define SENSOR_SERVICE_HMAC_KEY_FILE SENSOR_SERVICE_DIR "/hmac_key"
		#define SENSOR_SERVICE_SCHED_FIFO_PRIORITY 10

		// Permissions.
		static const String16 sDump("android.permission.DUMP");
		@@ -117,6 +119,15 @@ bool SensorService::initializeHmacKey() {
		return true;
		}

		// Set main thread to SCHED_FIFO to lower sensor event latency when system is under load
		void SensorService::enableSchedFifoMode() {
		struct sched_param param = {0};
		param.sched_priority = SENSOR_SERVICE_SCHED_FIFO_PRIORITY;
		if (sched_setscheduler(getTid(), SCHED_FIFO \| SCHED_RESET_ON_FORK, &param) != 0) {
		ALOGE("Couldn't set SCHED_FIFO for SensorService thread");
		}
		}

		void SensorService::onFirstRef() {
		ALOGD("nuSensorService starting...");
		SensorDevice& dev(SensorDevice::getInstance());
		@@ -261,6 +272,9 @@ void SensorService::onFirstRef() {
		mAckReceiver = new SensorEventAckReceiver(this);
		mAckReceiver->run("SensorEventAckReceiver", PRIORITY_URGENT_DISPLAY);
		run("SensorService", PRIORITY_URGENT_DISPLAY);

		// priority can only be changed after run
		enableSchedFifoMode();
		}
		}
		}

+2 −0

Original line number	Diff line number	Diff line
		@@ -215,6 +215,8 @@ private:
		// Either read from storage or create a new one.
		static bool initializeHmacKey();

		// Enable SCHED_FIFO priority for thread
		void enableSchedFifoMode();

		static uint8_t sHmacGlobalKey[128];
		static bool sHmacGlobalKeyIsValid;