Merge "Metrics for touch latency" (3c252c2c) · Commits · e / os / platform_frameworks_native

services/inputflinger/Android.bp

+2 −1

Original line number	Diff line number	Diff line
		@@ -76,7 +76,8 @@ cc_library_shared {
		"libutils",
		"libui",
		"libhardware_legacy",
		"libutils"
		"libstatslog",
		"libutils",
		],

		header_libs: [

services/inputflinger/InputReader.cpp

+21 −4

Original line number	Diff line number	Diff line
		@@ -57,6 +57,7 @@
		#include <android-base/stringprintf.h>
		#include <input/Keyboard.h>
		#include <input/VirtualKeyMap.h>
		#include <statslog.h>

		#define INDENT " "
		#define INDENT2 " "
		@@ -71,18 +72,21 @@ namespace android {
		// --- Constants ---

		// Maximum number of slots supported when using the slot-based Multitouch Protocol B.
		static const size_t MAX_SLOTS = 32;
		static constexpr size_t MAX_SLOTS = 32;

		// Maximum amount of latency to add to touch events while waiting for data from an
		// external stylus.
		static const nsecs_t EXTERNAL_STYLUS_DATA_TIMEOUT = ms2ns(72);
		static constexpr nsecs_t EXTERNAL_STYLUS_DATA_TIMEOUT = ms2ns(72);

		// Maximum amount of time to wait on touch data before pushing out new pressure data.
		static const nsecs_t TOUCH_DATA_TIMEOUT = ms2ns(20);
		static constexpr nsecs_t TOUCH_DATA_TIMEOUT = ms2ns(20);

		// Artificial latency on synthetic events created from stylus data without corresponding touch
		// data.
		static const nsecs_t STYLUS_DATA_LATENCY = ms2ns(10);
		static constexpr nsecs_t STYLUS_DATA_LATENCY = ms2ns(10);

		// How often to report input event statistics
		static constexpr nsecs_t STATISTICS_REPORT_FREQUENCY = seconds_to_nanoseconds(5 * 60);

		// --- Static Functions ---

		@@ -4287,12 +4291,25 @@ void TouchInputMapper::clearStylusDataPendingFlags() {
		mExternalStylusFusionTimeout = LLONG_MAX;
		}

		void TouchInputMapper::reportEventForStatistics(nsecs_t evdevTime) {
		nsecs_t now = systemTime(CLOCK_MONOTONIC);
		nsecs_t latency = now - evdevTime;
		mStatistics.addValue(nanoseconds_to_microseconds(latency));
		nsecs_t timeSinceLastReport = now - mStatistics.lastReportTime;
		if (timeSinceLastReport > STATISTICS_REPORT_FREQUENCY) {
		android::util::stats_write(android::util::TOUCH_EVENT_REPORTED,
		mStatistics.min, mStatistics.max, mStatistics.mean(), mStatistics.stdev());
		mStatistics.reset(now);
		}
		}

		void TouchInputMapper::process(const RawEvent* rawEvent) {
		mCursorButtonAccumulator.process(rawEvent);
		mCursorScrollAccumulator.process(rawEvent);
		mTouchButtonAccumulator.process(rawEvent);

		if (rawEvent->type == EV_SYN && rawEvent->code == SYN_REPORT) {
		reportEventForStatistics(rawEvent->when);
		sync(rawEvent->when);
		}
		}

services/inputflinger/InputReader.h

+68 −0

Original line number	Diff line number	Diff line
		@@ -567,6 +567,69 @@ struct CookedPointerData {
		}
		};

		/**
		* Basic statistics information.
		* Keep track of min, max, average, and standard deviation of the received samples.
		* Used to report latency information about input events.
		*/
		struct LatencyStatistics {
		float min;
		float max;
		// Sum of all samples
		float sum;
		// Sum of squares of all samples
		float sum2;
		// The number of samples
		size_t count;
		// The last time statistics were reported.
		nsecs_t lastReportTime;

		LatencyStatistics() {
		reset(systemTime(SYSTEM_TIME_MONOTONIC));
		}

		inline void addValue(float x) {
		if (x < min) {
		min = x;
		}
		if (x > max) {
		max = x;
		}
		sum += x;
		sum2 += x * x;
		count++;
		}

		// Get the average value. Should not be called if no samples have been added.
		inline float mean() {
		if (count == 0) {
		return 0;
		}
		return sum / count;
		}

		// Get the standard deviation. Should not be called if no samples have been added.
		inline float stdev() {
		if (count == 0) {
		return 0;
		}
		float average = mean();
		return sqrt(sum2 / count - average * average);
		}

		/**
		* Reset internal state. The variable 'when' is the time when the data collection started.
		* Call this to start a new data collection window.
		*/
		inline void reset(nsecs_t when) {
		max = 0;
		min = std::numeric_limits<float>::max();
		sum = 0;
		sum2 = 0;
		count = 0;
		lastReportTime = when;
		}
		};

		/* Keeps track of the state of single-touch protocol. */
		class SingleTouchMotionAccumulator {
		@@ -1511,6 +1574,9 @@ private:
		VelocityControl mWheelXVelocityControl;
		VelocityControl mWheelYVelocityControl;

		// Latency statistics for touch events
		struct LatencyStatistics mStatistics;

		std::optional<DisplayViewport> findViewport();

		void resetExternalStylus();
		@@ -1580,6 +1646,8 @@ private:

		static void assignPointerIds(const RawState* last, RawState* current);

		void reportEventForStatistics(nsecs_t evdevTime);

		const char* modeToString(DeviceMode deviceMode);
		};