Some sanitize changes on latency

src/android/app/src/main/jni/emu_window/emu_window.cpp

@@ -124,9 +124,18 @@ float EmuWindow_Android::GetFrameTimeVerifiedHint() const {
     return QuantizeFrameRateHint(verified_rate);
 }
 
+float EmuWindow_Android::GetPresentedFrameMultiplier() {
+    if (!Settings::values.frame_gen.GetValue()) {
+        return 1.0f;
+    }
+    return static_cast<float>(std::clamp<u32>(Settings::values.frame_gen_multiplier.GetValue(), 2, 4));
+}
+
 float EmuWindow_Android::GetFrameRateHint() const {
-    const float observed_rate = std::clamp(m_smoothed_present_rate, 0.0f, 240.0f);
-    const float frame_time_verified_hint = GetFrameTimeVerifiedHint();
+    const float presented_multiplier = GetPresentedFrameMultiplier();
+    const float observed_rate =
+        std::clamp(m_smoothed_present_rate * presented_multiplier, 0.0f, 240.0f);
+    const float frame_time_verified_hint = GetFrameTimeVerifiedHint() * presented_multiplier;
 
     if (m_last_frame_rate_hint > 0.0f && observed_rate > 0.0f) {
         const float tolerance = std::max(m_last_frame_rate_hint * 0.12f, 4.0f);
@@ -150,9 +159,9 @@ float EmuWindow_Android::GetFrameRateHint() const {
         return frame_time_verified_hint;
     }
 
-    constexpr float NominalFrameRate = 60.0f;
+    const float nominal_rate = 60.0f * presented_multiplier;
     if (!Settings::values.use_speed_limit.GetValue()) {
-        return NominalFrameRate;
+        return QuantizeFrameRateHint(nominal_rate);
     }
 
     const u16 speed_limit = Settings::SpeedLimit();
@@ -161,7 +170,7 @@ float EmuWindow_Android::GetFrameRateHint() const {
     }
 
     const float speed_limited_rate =
-        NominalFrameRate * (static_cast<float>(std::min<u16>(speed_limit, 100)) / 100.0f);
+        nominal_rate * (static_cast<float>(std::min<u16>(speed_limit, 100)) / 100.0f);
     return QuantizeFrameRateHint(speed_limited_rate);
 }
 

src/android/app/src/main/jni/emu_window/emu_window.h

@@ -61,6 +61,7 @@ private:
     void UpdateObservedFrameRate();
     [[nodiscard]] float GetFrameRateHint() const;
     [[nodiscard]] float GetFrameTimeVerifiedHint() const;
+    [[nodiscard]] static float GetPresentedFrameMultiplier();
     [[nodiscard]] static float QuantizeFrameRateHint(float frame_rate);
 
     float m_window_width{};

src/android/app/src/main/res/values/strings.xml

@@ -299,7 +299,7 @@
     <string name="gpu_driver_manager">GPU driver manager</string>
     <string name="install_gpu_driver_description">Install alternative drivers for potentially better performance or accuracy</string>
     <string name="frame_gen">Frame generation</string>
-    <string name="frame_gen_description">Run the Lossless Scaling interpolation shaders on every frame. Incomplete: the interpolated frame is computed but not yet displayed, so this only costs performance for now.</string>
+    <string name="frame_gen_description">Insert interpolated frames between rendered ones using Lossless Scaling. Forces FIFO presentation while enabled, since other modes discard the generated frames. Adds about one frame of latency.</string>
     <string name="frame_gen_multiplier">Frame multiplier</string>
     <string name="frame_gen_multiplier_description">How many frames to display for each rendered frame. Higher values cost proportionally more GPU time.</string>
     <string name="frame_gen_multiplier_2x">2x (one generated frame)</string>

src/video_core/renderer_vulkan/vk_scheduler.h

@@ -146,9 +146,10 @@ public:
             frame_counter++;
             auto target_time = start_time + frame_interval * frame_counter;
             if (target_time >= now) {
+                constexpr auto spin_tail = std::chrono::milliseconds(1);
                 auto sleep_time = target_time - now;
-                if (sleep_time > std::chrono::milliseconds(15)) {
-                    std::this_thread::sleep_for(sleep_time - std::chrono::milliseconds(1));
+                if (sleep_time > spin_tail * 2) {
+                    std::this_thread::sleep_for(sleep_time - spin_tail);
                 }
                 while (std::chrono::steady_clock::now() < target_time) {
                     std::this_thread::yield();

src/video_core/renderer_vulkan/vk_swapchain.cpp

@@ -48,6 +48,9 @@ static VkPresentModeKHR ChooseSwapPresentMode(bool has_imm, bool has_mailbox,
     Settings::VSyncMode setting = [has_imm, has_mailbox]() {
         // Choose Mailbox or Immediate if unlocked and those modes are supported
         const auto mode = Settings::values.vsync_mode.GetValue();
+        if (Settings::values.frame_gen.GetValue()) {
+            return mode == Settings::VSyncMode::FifoRelaxed ? mode : Settings::VSyncMode::Fifo;
+        }
         if (Settings::values.use_speed_limit.GetValue() &&
             Settings::values.current_speed_mode.GetValue() != Settings::SpeedMode::Turbo) {
             return mode;