Defer frame waits if possible

Core/FrameTiming.cpp

@@ -32,6 +32,19 @@
 
 FrameTiming g_frameTiming;
 
+void WaitUntil(double now, double timestamp) {
+#ifdef _WIN32
+	while (time_now_d() < timestamp) {
+		sleep_ms(1); // Sleep for 1ms on this thread
+	}
+#else
+	const double left = timestamp - now;
+	if (left > 0.0) {
+		usleep((long)(left * 1000000));
+	}
+#endif
+}
+
 inline Draw::PresentMode GetBestImmediateMode(Draw::PresentMode supportedModes) {
 	if (supportedModes & Draw::PresentMode::MAILBOX) {
 		return Draw::PresentMode::MAILBOX;
@@ -50,6 +63,22 @@ void FrameTiming::Reset(Draw::DrawContext *draw) {
 	}
 }
 
+void FrameTiming::DeferWaitUntil(double until, double *curTimePtr) {
+	_dbg_assert_(until > 0.0);
+	waitUntil_ = until;
+	curTimePtr_ = curTimePtr;
+}
+
+void FrameTiming::PostSubmit() {
+	if (waitUntil_ != 0.0) {
+		WaitUntil(time_now_d(), waitUntil_);
+		if (curTimePtr_) {
+			*curTimePtr_ = waitUntil_;
+		}
+		waitUntil_ = 0.0;
+	}
+}
+
 Draw::PresentMode ComputePresentMode(Draw::DrawContext *draw, int *interval) {
 	Draw::PresentMode mode = Draw::PresentMode::FIFO;
 

Core/FrameTiming.h

@@ -8,14 +8,23 @@ namespace Draw {
 class DrawContext;
 }
 
-struct FrameTiming {
+class FrameTiming {
+public:
+	void DeferWaitUntil(double until, double *curTimePtr);
+	void PostSubmit();
+	void Reset(Draw::DrawContext *draw);
+
 	// Some backends won't allow changing this willy nilly.
 	Draw::PresentMode presentMode;
 	int presentInterval;
 
-	void Reset(Draw::DrawContext *draw);
+private:
+	double waitUntil_;
+	double *curTimePtr_;
 };
 
 extern FrameTiming g_frameTiming;
 
 Draw::PresentMode ComputePresentMode(Draw::DrawContext *draw, int *interval);
+
+void WaitUntil(double now, double timestamp);

Core/HLE/sceDisplay.cpp

@@ -391,7 +391,7 @@ static void DoFrameDropLogging(float scaledTimestep) {
 
 // All the throttling and frameskipping logic is here.
 // This is called just before we drop out of the main loop, in order to allow the submit and present to happen.
-static void DoFrameTiming(bool throttle, bool *skipFrame, float scaledTimestep) {
+static void DoFrameTiming(bool throttle, bool *skipFrame, float scaledTimestep, bool endOfFrame) {
 	PROFILE_THIS_SCOPE("timing");
 	*skipFrame = false;
 
@@ -438,16 +438,15 @@ static void DoFrameTiming(bool throttle, bool *skipFrame, float scaledTimestep)
 			nextFrameTime = curFrameTime;
 		} else {
 			// Wait until we've caught up.
-			while (time_now_d() < nextFrameTime) {
-#ifdef _WIN32
-				sleep_ms(1); // Sleep for 1ms on this thread
-#else
-				const double left = nextFrameTime - curFrameTime;
-				usleep((long)(left * 1000000));
-#endif
+			// If we're ending the frame here, we'll defer the sleep until after the command buffers
+			// have been handed off to the render thread, for some more overlap.
+			if (endOfFrame) {
+				g_frameTiming.DeferWaitUntil(nextFrameTime, &curFrameTime);
+			} else {
+				WaitUntil(curFrameTime, nextFrameTime);
+				curFrameTime = time_now_d();  // I guess we could also just set it to nextFrameTime...
 			}
 		}
-		curFrameTime = time_now_d();
 	}
 
 	lastFrameTime = nextFrameTime;
@@ -637,9 +636,14 @@ void __DisplayFlip(int cyclesLate) {
 
 	// Setting CORE_NEXTFRAME (which Core_NextFrame does) causes a swap.
 	const bool fbReallyDirty = gpu->FramebufferReallyDirty();
+
+	bool nextFrame = false;
+
 	if (fbReallyDirty || noRecentFlip || postEffectRequiresFlip) {
 		// Check first though, might've just quit / been paused.
-		if (!forceNoFlip && Core_NextFrame()) {
+		if (!forceNoFlip)
+			nextFrame = Core_NextFrame();
+		if (nextFrame) {
 			gpu->CopyDisplayToOutput(fbReallyDirty);
 			if (fbReallyDirty) {
 				DisplayFireActualFlip();
@@ -659,7 +663,7 @@ void __DisplayFlip(int cyclesLate) {
 		scaledTimestep *= (float)framerate / fpsLimit;
 	}
 	bool skipFrame;
-	DoFrameTiming(throttle, &skipFrame, scaledTimestep);
+	DoFrameTiming(throttle, &skipFrame, scaledTimestep, nextFrame);
 
 	int maxFrameskip = 8;
 	int frameSkipNum = DisplayCalculateFrameSkip();

UI/NativeApp.cpp

@@ -1117,6 +1117,7 @@ void NativeFrame(GraphicsContext *graphicsContext) {
 
 	// This, between EndFrame and Present, is where we should actually wait to do present time management.
 	// There might not be a meaningful distinction here for all backends..
+	g_frameTiming.PostSubmit();
 
 	if (renderCounter < 10 && ++renderCounter == 10) {
 		// We're rendering fine, clear out failure info.