Refactor PhysicalDevice selection

asuessenbach · asuessenbach · commit 9b47b093598b · 2026-02-10T14:25:12.000+01:00
diff --git a/app/plugins/gpu_selection/gpu_selection.cpp b/app/plugins/gpu_selection/gpu_selection.cpp
@@ -1,5 +1,5 @@
-/* Copyright (c) 2023-2025, Sascha Willems
- * Copyright (c) 2025, NVIDIA CORPORATION. All rights reserved.
+/* Copyright (c) 2023-2026, Sascha Willems
+ * Copyright (c) 2025-2026, NVIDIA CORPORATION. All rights reserved.
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -18,6 +18,7 @@
 
 #include "gpu_selection.h"
 #include "core/instance.h"
+#include "vulkan_sample.h"
 
 #include <algorithm>
 
@@ -45,8 +46,8 @@ bool GpuSelection::handle_option(std::deque<std::string> &arguments)
 		}
 		uint32_t gpu_index = static_cast<uint32_t>(std::stoul(arguments[1]));
 
-		vkb::core::InstanceC::selected_gpu_index   = gpu_index;
-		vkb::core::InstanceCpp::selected_gpu_index = gpu_index;
+		vkb::VulkanSampleC::selected_gpu_index   = gpu_index;
+		vkb::VulkanSampleCpp::selected_gpu_index = gpu_index;
 
 		arguments.pop_front();
 		arguments.pop_front();
diff --git a/framework/core/instance.h b/framework/core/instance.h
@@ -59,11 +59,6 @@ class Instance
 	using SurfaceType             = typename std::conditional<bindingType == vkb::BindingType::Cpp, vk::SurfaceKHR, VkSurfaceKHR>::type;
 
   public:
-	/**
-	 * @brief Can be set from the GPU selection plugin to explicitly select a GPU instead
-	 */
-	inline static uint32_t selected_gpu_index = ~0;
-
 	/**
 	 * @brief Initializes the connection to Vulkan
 	 * @param application_name The name of the application
@@ -112,38 +107,17 @@ class Instance
 
 	const std::vector<std::string> &get_extensions();
 
-	/**
-	 * @brief Tries to find the first available discrete GPU
-	 * @returns A valid physical device
-	 */
-	PhysicalDevice<bindingType> &get_first_gpu();
-
 	InstanceType get_handle() const;
 
-	/**
-	 * @brief Tries to find the first available discrete GPU that can render to the given surface
-	 * @param surface to test against
-	 * @param headless_surface Is surface created with VK_EXT_headless_surface
-	 * @returns A valid physical device
-	 */
-	PhysicalDevice<bindingType> &get_suitable_gpu(SurfaceType surface, bool headless_surface);
-
 	/**
 	 * @brief Checks if the given extension is enabled in the InstanceType
 	 * @param extension An extension to check
 	 */
 	bool is_enabled(char const *extension) const;
 
   private:
-	/**
-	 * @brief Queries the instance for the physical devices on the machine
-	 */
-	void query_gpus();
-
-  private:
-	std::vector<std::string>                                   enabled_extensions;        // The enabled extensions
-	std::vector<std::unique_ptr<vkb::core::PhysicalDeviceCpp>> gpus;                      // The physical devices found on the machine
-	vk::Instance                                               handle;                    // The Vulkan instance
+	std::vector<std::string> enabled_extensions;        // The enabled extensions
+	vk::Instance             handle;                    // The Vulkan instance
 
 #if defined(VKB_DEBUG) || defined(VKB_VALIDATION_LAYERS)
 	vk::DebugReportCallbackEXT debug_report_callback;        // The debug report callback
@@ -349,8 +323,6 @@ inline Instance<bindingType>::Instance(std::string const
 		debug_report_callback = handle.createDebugReportCallbackEXT(vkb::core::getDefaultDebugReportCallbackCreateInfoEXT());
 	}
 #endif
-
-	query_gpus();
 }
 
 template <vkb::BindingType bindingType>
@@ -375,15 +347,6 @@ inline Instance<bindingType>::Instance(vk::Instance instance, const std::vector<
 	{
 		enabled_extensions.push_back(extension);
 	}
-
-	if (handle)
-	{
-		query_gpus();
-	}
-	else
-	{
-		throw std::runtime_error("Instance not valid");
-	}
 }
 
 template <vkb::BindingType bindingType>
@@ -419,28 +382,6 @@ inline Instance<bindingType>::~Instance()
 #	undef USE_VALIDATION_LAYER_FEATURES
 #endif
 
-template <vkb::BindingType bindingType>
-inline PhysicalDevice<bindingType> &Instance<bindingType>::get_first_gpu()
-{
-	assert(!gpus.empty() && "No physical devices were found on the system.");
-
-	// Find a discrete GPU
-	auto gpuIt = std::ranges::find_if(gpus, [](auto const &gpu) { return gpu->get_properties().deviceType == vk::PhysicalDeviceType::eDiscreteGpu; });
-	if (gpuIt == gpus.end())
-	{
-		LOGW("Couldn't find a discrete physical device, picking default GPU");
-		gpuIt = gpus.begin();
-	}
-	if constexpr (bindingType == BindingType::Cpp)
-	{
-		return **gpuIt;
-	}
-	else
-	{
-		return reinterpret_cast<vkb::core::PhysicalDeviceC &>(**gpuIt);
-	}
-}
-
 template <vkb::BindingType bindingType>
 inline typename Instance<bindingType>::InstanceType Instance<bindingType>::get_handle() const
 {
@@ -455,103 +396,13 @@ inline typename Instance<bindingType>::InstanceType Instance<bindingType>::get_h
 	return handle;
 }
 
-template <vkb::BindingType bindingType>
-inline PhysicalDevice<bindingType> &Instance<bindingType>::get_suitable_gpu(SurfaceType surface, bool headless_surface)
-{
-	assert(!gpus.empty() && "No physical devices were found on the system.");
-
-	// A GPU can be explicitly selected via the command line (see plugins/gpu_selection.cpp), this overrides the below GPU selection algorithm
-	auto gpuIt = gpus.begin();
-	if (selected_gpu_index != ~0)
-	{
-		LOGI("Explicitly selecting GPU {}", selected_gpu_index);
-		if (selected_gpu_index > gpus.size() - 1)
-		{
-			throw std::runtime_error("Selected GPU index is not within no. of available GPUs");
-		}
-		gpuIt = gpus.begin() + selected_gpu_index;
-	}
-	else
-	{
-		if (headless_surface)
-		{
-			LOGW("Using headless surface with multiple GPUs. Considered explicitly selecting the target GPU.")
-		}
-
-		// Find a discrete GPU
-#if 0
-		gpuIt = std::ranges::find_if(gpus,
-		                             [&surface](auto const &gpu) {
-			                             return (gpu->get_properties().deviceType == vk::PhysicalDeviceType::eDiscreteGpu) &&
-			                                    std::ranges::any_of(std::views::iota(size_t(0), gpu->get_queue_family_properties().size()),
-			                                                        [&gpu, &surface](auto const &queue_idx) {
-				                                                        return gpu->get_handle().getSurfaceSupportKHR(static_cast<uint32_t>(queue_idx), surface);
-			                                                        });
-		                             });
-#else
-		gpuIt = std::ranges::find_if(gpus,
-		                             [&surface](auto const &gpu) {
-			                             auto gpu_supports_surface = [&gpu, &surface]() {
-				                             for (uint32_t queue_idx = 0; queue_idx < gpu->get_queue_family_properties().size(); ++queue_idx)
-				                             {
-					                             if (gpu->get_handle().getSurfaceSupportKHR(queue_idx, surface))
-					                             {
-						                             return true;
-					                             }
-				                             }
-				                             return false;
-			                             };
-			                             return (gpu->get_properties().deviceType == vk::PhysicalDeviceType::eDiscreteGpu) && gpu_supports_surface();
-		                             });
-#endif
-		if (gpuIt == gpus.end())
-		{
-			LOGW("Couldn't find a discrete physical device that supports the surface, picking default GPU");
-			gpuIt = gpus.begin();
-		}
-	}
-
-	if constexpr (bindingType == BindingType::Cpp)
-	{
-		return **gpuIt;
-	}
-	else
-	{
-		return reinterpret_cast<vkb::core::PhysicalDeviceC &>(**gpuIt);
-	}
-}
-
 template <vkb::BindingType bindingType>
 inline bool Instance<bindingType>::is_enabled(char const *extension) const
 {
 	return std::ranges::find_if(enabled_extensions, [extension](std::string const &enabled_extension) { return enabled_extension == extension; }) !=
 	       enabled_extensions.end();
 }
 
-template <vkb::BindingType bindingType>
-inline void Instance<bindingType>::query_gpus()
-{
-	// Querying valid physical devices on the machine
-	std::vector<vk::PhysicalDevice> physical_devices = handle.enumeratePhysicalDevices();
-	if (physical_devices.empty())
-	{
-		throw std::runtime_error("Couldn't find a physical device that supports Vulkan.");
-	}
-
-	// Create gpus wrapper objects from the vk::PhysicalDevice's
-	for (auto &physical_device : physical_devices)
-	{
-		if constexpr (bindingType == BindingType::Cpp)
-		{
-			gpus.push_back(std::make_unique<vkb::core::PhysicalDeviceCpp>(*this, physical_device));
-		}
-		else
-		{
-			gpus.push_back(std::make_unique<vkb::core::PhysicalDeviceCpp>(*reinterpret_cast<vkb::core::InstanceCpp *>(this), physical_device));
-		}
-	}
-}
-
 template <vkb::BindingType bindingType>
 inline std::vector<std::string> const &Instance<bindingType>::get_extensions()
 {
diff --git a/framework/platform/unix/direct_window.cpp b/framework/platform/unix/direct_window.cpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2019-2025, Arm Limited and Contributors
+/* Copyright (c) 2019-2026, Arm Limited and Contributors
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -242,22 +242,6 @@ DirectWindow::~DirectWindow()
 	}
 }
 
-VkSurfaceKHR DirectWindow::create_surface(vkb::core::InstanceC &instance)
-{
-	return create_surface(instance.get_handle(), instance.get_first_gpu().get_handle());
-}
-
-// Local structure for holding display candidate information
-struct Candidate
-{
-	VkDisplayKHR                  display;
-	VkDisplayPropertiesKHR        display_props;
-	VkDisplayModePropertiesKHR    mode;
-	VkDisplayPlaneCapabilitiesKHR caps;
-	uint32_t                      plane_index;
-	uint32_t                      stack_index;
-};
-
 // Helper template to get a vector of properties using the Vulkan idiom of
 // querying size, then querying data
 template <typename T, typename F, typename... Targs>
@@ -275,6 +259,22 @@ static std::vector<T> get_props(F func, Targs... args)
 	return result;
 }
 
+VkSurfaceKHR DirectWindow::create_surface(vkb::core::InstanceC &instance)
+{
+	return create_surface(instance.get_handle(), get_props<VkPhysicalDevice>(vkEnumeratePhysicalDevices, instance.get_handle()).front());
+}
+
+// Local structure for holding display candidate information
+struct Candidate
+{
+	VkDisplayKHR                  display;
+	VkDisplayPropertiesKHR        display_props;
+	VkDisplayModePropertiesKHR    mode;
+	VkDisplayPlaneCapabilitiesKHR caps;
+	uint32_t                      plane_index;
+	uint32_t                      stack_index;
+};
+
 // Find all valid display candidates in the system
 static std::vector<Candidate> find_display_candidates(VkPhysicalDevice phys_dev, Window::Mode window_mode)
 {
diff --git a/framework/vulkan_sample.h b/framework/vulkan_sample.h
