Add option to align buffer-memory

- use for sbt- and acceleration-structure scratch
crocdialer · Sep 25, 2024 · ac00365 · ac00365
1 parent 470a748
commit ac00365
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Showing 4 changed files with 38 additions and 20 deletions.
diff --git a/include/vierkant/Buffer.hpp b/include/vierkant/Buffer.hpp
@@ -34,7 +34,8 @@ class Buffer
     {
         DevicePtr device;
         const void *data = nullptr;
-        size_t num_bytes = 0;
+        uint64_t num_bytes = 0;
+        uint32_t alignment = 0;
         VkBufferUsageFlags usage = 0;
         VmaMemoryUsage mem_usage = VMA_MEMORY_USAGE_UNKNOWN;
         VmaPoolPtr pool;
@@ -157,6 +158,8 @@ class Buffer
     [[nodiscard]] vierkant::DevicePtr device() const { return m_device; }
 
 private:
+    explicit Buffer(const create_info_t &create_info);
+
     DevicePtr m_device;
 
     VkBuffer m_buffer = VK_NULL_HANDLE;
@@ -175,11 +178,11 @@ class Buffer
 
     VmaMemoryUsage m_mem_usage = VMA_MEMORY_USAGE_UNKNOWN;
 
+    uint32_t m_min_alignment = 0;
+
     VmaPoolPtr m_pool = nullptr;
 
     std::string m_name;
-
-    Buffer(const create_info_t &create_info);
 };
 
 }// namespace vierkant
diff --git a/src/Buffer.cpp b/src/Buffer.cpp
@@ -131,7 +131,7 @@ BufferPtr Buffer::create(DevicePtr device, const void *data, size_t num_bytes, V
 
 Buffer::Buffer(const create_info_t &create_info)
     : m_device(create_info.device), m_usage(create_info.usage), m_mem_usage(create_info.mem_usage),
-      m_pool(create_info.pool), m_name(create_info.name)
+      m_min_alignment(create_info.alignment), m_pool(create_info.pool), m_name(create_info.name)
 {}
 
 Buffer::~Buffer()
@@ -210,8 +210,8 @@ void Buffer::set_data(const void *data, size_t num_bytes)
         alloc_info.usage = m_mem_usage;
         alloc_info.pool = m_pool.get();
 
-        vmaCreateBuffer(m_device->vk_mem_allocator(), &buffer_info, &alloc_info, &m_buffer, &m_allocation,
-                        &m_allocation_info);
+        vmaCreateBufferWithAlignment(m_device->vk_mem_allocator(), &buffer_info, &alloc_info, m_min_alignment,
+                                     &m_buffer, &m_allocation, &m_allocation_info);
 
         //! set optional name for debugging
         if(!m_name.empty()) { m_device->set_object_name(uint64_t(m_buffer), VK_OBJECT_TYPE_BUFFER, m_name); }

diff --git a/src/RayBuilder.cpp b/src/RayBuilder.cpp
@@ -219,12 +219,16 @@ RayBuilder::build_result_t RayBuilder::create_mesh_structures(const create_mesh_
         acceleration_asset.vertex_buffer = vertex_buffer;
         acceleration_asset.vertex_buffer_offset = vertex_buffer_offset;
 
-        // Allocate the scratch buffers holding the temporary data of the
-        // acceleration structure builder
-        acceleration_asset.scratch_buffer =
-                vierkant::Buffer::create(m_device, nullptr, std::max<uint64_t>(size_info.buildScratchSize, 1 << 12U),
-                                         VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT,
-                                         VMA_MEMORY_USAGE_GPU_ONLY, m_memory_pool);
+        // allocate a scratch buffer for temporary data during acceleration-structure building
+        vierkant::Buffer::create_info_t scratch_buffer_info = {};
+        scratch_buffer_info.device = m_device;
+        scratch_buffer_info.pool = m_memory_pool;
+        scratch_buffer_info.num_bytes = std::max<uint64_t>(size_info.buildScratchSize, 1 << 12U);
+        scratch_buffer_info.alignment =
+                m_device->properties().acceleration_structure.minAccelerationStructureScratchOffsetAlignment;
+        scratch_buffer_info.usage = VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT;
+        scratch_buffer_info.mem_usage = VMA_MEMORY_USAGE_GPU_ONLY;
+        acceleration_asset.scratch_buffer = vierkant::Buffer::create(scratch_buffer_info);
 
         // assign acceleration structure and scratch_buffer
         build_info.dstAccelerationStructure = acceleration_asset.structure.get();
@@ -902,10 +906,15 @@ RayBuilder::scene_acceleration_context_ptr RayBuilder::create_scene_acceleration
             vierkant::create_query_pool(m_device, 2 * UpdateSemaphoreValue::MAX_VALUE, VK_QUERY_TYPE_TIMESTAMP);
 
     // Create a small scratch buffer used during build of the top level acceleration structure
-    ret->scratch_buffer_top =
-            vierkant::Buffer::create(m_device, nullptr, 1U << 12U,
-                                     VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT,
-                                     VMA_MEMORY_USAGE_GPU_ONLY, m_memory_pool);
+    vierkant::Buffer::create_info_t scratch_buffer_info = {};
+    scratch_buffer_info.device = m_device;
+    scratch_buffer_info.pool = m_memory_pool;
+    scratch_buffer_info.num_bytes = 1U << 12U;
+    scratch_buffer_info.alignment =
+            m_device->properties().acceleration_structure.minAccelerationStructureScratchOffsetAlignment;
+    scratch_buffer_info.usage = VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT | VK_BUFFER_USAGE_STORAGE_BUFFER_BIT;
+    scratch_buffer_info.mem_usage = VMA_MEMORY_USAGE_GPU_ONLY;
+    ret->scratch_buffer_top = vierkant::Buffer::create(scratch_buffer_info);
     return ret;
 }
 

diff --git a/src/RayTracer.cpp b/src/RayTracer.cpp
@@ -179,10 +179,16 @@ RayTracer::create_shader_binding_table(VkPipeline pipeline, const vierkant::rayt
                 aligned_size(group_elements[Group(g)] * handle_size_aligned, ray_props.shaderGroupBaseAlignment);
         binding_table_size += binding_table.strided_address_region[g].size;
     }
-    binding_table.buffer = vierkant::Buffer::create(m_device, nullptr, binding_table_size,
-                                                    VK_BUFFER_USAGE_SHADER_BINDING_TABLE_BIT_KHR |
-                                                            VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT,
-                                                    VMA_MEMORY_USAGE_CPU_TO_GPU);
+
+    vierkant::Buffer::create_info_t binding_table_buffer_info = {};
+    binding_table_buffer_info.device = m_device;
+    binding_table_buffer_info.num_bytes = binding_table_size;
+    binding_table_buffer_info.alignment = ray_props.shaderGroupBaseAlignment;
+    binding_table_buffer_info.usage =
+            VK_BUFFER_USAGE_SHADER_BINDING_TABLE_BIT_KHR | VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT;
+    binding_table_buffer_info.mem_usage = VMA_MEMORY_USAGE_CPU_TO_GPU;
+    binding_table.buffer = vierkant::Buffer::create(binding_table_buffer_info);
+
     // shader groups
     auto group_create_infos = vierkant::raytracing_shader_groups(shader_stages);