Made CPU wait for N-1 GPU to finish

Supercomet · Sep 26, 2023 · d817657 · d817657
1 parent 19ec1b6
commit d817657
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Showing 3 changed files with 19 additions and 4 deletions.
diff --git a/Application/src/TestApplication.cpp b/Application/src/TestApplication.cpp
@@ -770,6 +770,8 @@ void TestApplication::Run()
         while (mainWindow.windowShouldClose == false)
         {
             PROFILE_FRAME("MainThread");
+            int64_t frame = std::max<int64_t>(int64_t(m_ApplicationFrame) - 1, 0);
+            gs_RenderEngine->CPUwaitforGPU(frame);
 
 			auto now = std::chrono::high_resolution_clock::now();
 			float deltaTime = std::chrono::duration<float>(now - lastTime).count();

diff --git a/OO_Vulkan/src/VulkanRenderer.cpp b/OO_Vulkan/src/VulkanRenderer.cpp
@@ -1327,6 +1327,12 @@ int32_t VulkanRenderer::GetPixelValue(uint32_t fbID, glm::vec2 uv)
 
 }
 
+void VulkanRenderer::CPUwaitforGPU(size_t frameNum)
+{
+	std::unique_lock l(cpuMutex);
+	cpuCV.wait(l, [f = frameNum, &gpu = CurrentFrameGPU] { return gpu > f; });
+}
+
 void VulkanRenderer::CreateLightingBuffers()
 {
 	//oGFX::CreateBuffer(m_device.physicalDevice, m_device.logicalDevice, sizeof(CB::LightUBO), 
@@ -2226,10 +2232,12 @@ void VulkanRenderer::BeginDraw()
 {
 	PROFILE_SCOPED();
 
-	//vkWaitForFences(m_device.logicalDevice, 1, &drawFences[getFrame()], VK_TRUE, UINT64_MAX);
-	uint64_t res{};
-	VK_CHK(vkGetSemaphoreCounterValue(m_device.logicalDevice, frameCountSemaphore, &res));
-	//printf("[FRAME COUNTER %5llu]\n", res);
+	{
+		std::scoped_lock l{cpuMutex};
+		VK_CHK(vkGetSemaphoreCounterValue(m_device.logicalDevice, frameCountSemaphore, &CurrentFrameGPU));
+		//printf("[FRAME COUNTER %5llu]\n", res);
+	}
+	cpuCV.notify_one(); // wake up the CPU waiting for N-1 frame
 
 	//wait for given fence to signal from last draw before continuing
 	VK_CHK(vkWaitForFences(m_device.logicalDevice, 1, &drawFences[getFrame()], VK_TRUE, std::numeric_limits<uint64_t>::max()));

diff --git a/OO_Vulkan/src/VulkanRenderer.h b/OO_Vulkan/src/VulkanRenderer.h
@@ -302,6 +302,8 @@ class VulkanRenderer
 
 	bool deferredRendering = true;
 
+	void CPUwaitforGPU(size_t frameNum);
+
 	void CreateLightingBuffers();
 	void UploadLights();
 	void UploadBones();
@@ -441,6 +443,9 @@ class VulkanRenderer
 	std::vector<VkSemaphore> renderSemaphore;
 	std::vector<VkFence> drawFences;
 	VkSemaphore frameCountSemaphore;
+	size_t CurrentFrameGPU{};
+	std::condition_variable cpuCV;
+	std::mutex cpuMutex;
 
 	// - Pipeline
 	VkPipeline pso_utilFullscreenBlit;