[dxvk] Optimized buffer renaming

Helps applications which frequently update buffers
through either Map()/Unmap() or UpdateSubresource.

src/dxvk/dxvk_buffer.cpp

@@ -7,21 +7,50 @@ namespace dxvk {
           DxvkDevice*           device,
     const DxvkBufferCreateInfo& createInfo,
           VkMemoryPropertyFlags memoryType)
-  : m_device  (device),
-    m_info    (createInfo),
-    m_memFlags(memoryType),
-    m_resource(allocateResource()) {
+  : m_device        (device),
+    m_info          (createInfo),
+    m_memFlags      (memoryType) {
+    // Initialize a single backing bufer with one slice
+    m_physBuffers[0] = this->allocPhysicalBuffer(1);
+    m_physSlice      = this->allocPhysicalSlice();
+  }
+  
+  
+  void DxvkBuffer::rename(
+    const DxvkPhysicalBufferSlice& slice) {
+    m_physSlice = slice;
+  }
+  
+  
+  DxvkPhysicalBufferSlice DxvkBuffer::allocPhysicalSlice() {
+    if (m_physSliceId >= m_physBuffers[m_physBufferId]->sliceCount()) {
+      m_physBufferId = (m_physBufferId + 1) % m_physBuffers.size();
+      m_physSliceId  = 0;
+      
+      if ((m_physBuffers[m_physBufferId] == nullptr)
+       || (m_physBuffers[m_physBufferId]->sliceCount() < m_physSliceCount)) {
+        // Make sure that all buffers have the same size. If we don't do this,
+        // one of the physical buffers may grow indefinitely while the others
+        // remain small, depending on the usage pattern of the application.
+        m_physBuffers[m_physBufferId] = this->allocPhysicalBuffer(m_physSliceCount);
+      } else if (m_physBuffers[m_physBufferId]->isInUse()) {
+        // Allocate a new physical buffer if the current one is still in use.
+        // This also indicates that the buffer gets updated frequently, so we
+        // will double the size of the physical buffers to accomodate for it.
+        if (m_physBufferId == 0)
+          m_physSliceCount *= 2;
+        
+        m_physBuffers[m_physBufferId] = this->allocPhysicalBuffer(m_physSliceCount);
+      }
+    }
     
+    return m_physBuffers[m_physBufferId]->slice(m_physSliceId++);
   }
   
   
-  void DxvkBuffer::renameResource(const DxvkPhysicalBufferSlice& resource) {
-    m_resource = resource;
-  }
-  
-  
-  DxvkPhysicalBufferSlice DxvkBuffer::allocateResource() {
-    return m_device->allocBufferResource(m_info, m_memFlags)->slice(0);
+  Rc<DxvkPhysicalBuffer> DxvkBuffer::allocPhysicalBuffer(VkDeviceSize sliceCount) const {
+    TRACE(this, sliceCount);
+    return m_device->allocPhysicalBuffer(m_info, sliceCount, m_memFlags);
   }
   
   

src/dxvk/dxvk_buffer.h

@@ -49,7 +49,7 @@ namespace dxvk {
      * \returns Pointer to mapped memory region
      */
     void* mapPtr(VkDeviceSize offset) const {
-      return m_resource.mapPtr(offset);
+      return m_physSlice.mapPtr(offset);
     }
     
     /**
@@ -62,7 +62,7 @@ namespace dxvk {
      * \returns \c true if the buffer is in use
      */
     bool isInUse() const {
-      return m_resource.resource()->isInUse();
+      return m_physSlice.resource()->isInUse();
     }
     
     /**
@@ -72,27 +72,9 @@ namespace dxvk {
      * \returns The resource object
      */
     Rc<DxvkResource> resource() const {
-      return m_resource.resource();
+      return m_physSlice.resource();
     }
     
-    /**
-     * \brief Replaces backing resource
-     * 
-     * Replaces the underlying buffer and implicitly marks
-     * any buffer views using this resource as dirty. Do
-     * not call this directly as this is called implicitly
-     * by the context's \c invalidateBuffer method.
-     * \param [in] resource The new backing resource
-     */
-    void renameResource(
-      const DxvkPhysicalBufferSlice& resource);
-    
-    /**
-     * \brief Allocates new backing resource
-     * \returns The new buffer
-     */
-    DxvkPhysicalBufferSlice allocateResource();
-    
     /**
      * \brief Physical buffer slice
      * 
@@ -101,7 +83,7 @@ namespace dxvk {
      * \returns The backing slice
      */
     DxvkPhysicalBufferSlice slice() const {
-      return m_resource;
+      return m_physSlice;
     }
     
     /**
@@ -113,16 +95,48 @@ namespace dxvk {
      * \returns The sub slice
      */
     DxvkPhysicalBufferSlice subSlice(VkDeviceSize offset, VkDeviceSize length) const {
-      return m_resource.subSlice(offset, length);
+      return m_physSlice.subSlice(offset, length);
     }
     
+    /**
+     * \brief Replaces backing resource
+     * 
+     * Replaces the underlying buffer and implicitly marks
+     * any buffer views using this resource as dirty. Do
+     * not call this directly as this is called implicitly
+     * by the context's \c invalidateBuffer method.
+     * \param [in] slice The new backing resource
+     */
+    void rename(
+      const DxvkPhysicalBufferSlice& slice);
+    
+    /**
+     * \brief Allocates new physical resource
+     * 
+     * This method must not be called from multiple threads
+     * simultaneously, but it can be called in parallel with
+     * \ref rename and other methods of this class.
+     * \returns The new backing buffer slice
+     */
+    DxvkPhysicalBufferSlice allocPhysicalSlice();
+    
   private:
     
     DxvkDevice*             m_device;
     DxvkBufferCreateInfo    m_info;
     VkMemoryPropertyFlags   m_memFlags;
+    DxvkPhysicalBufferSlice m_physSlice;
     
-    DxvkPhysicalBufferSlice m_resource;
+    // TODO maybe align this to a cache line in order
+    // to avoid false sharing once CSMT is implemented
+    VkDeviceSize m_physBufferId   = 0;
+    VkDeviceSize m_physSliceId    = 0;
+    VkDeviceSize m_physSliceCount = 1;
+    
+    std::array<Rc<DxvkPhysicalBuffer>, 2> m_physBuffers;
+    
+    Rc<DxvkPhysicalBuffer> allocPhysicalBuffer(
+            VkDeviceSize    sliceCount) const;
     
   };
   

src/dxvk/dxvk_buffer_res.cpp

@@ -8,9 +8,10 @@ namespace dxvk {
           VkDeviceSize          sliceCount,
           DxvkMemoryAllocator&  memAlloc,
           VkMemoryPropertyFlags memFlags)
-  : m_vkd(vkd),
-    m_sliceLength(createInfo.size),
-    m_sliceStride(align(createInfo.size, 256)) {
+  : m_vkd         (vkd),
+    m_sliceCount  (sliceCount),
+    m_sliceLength (createInfo.size),
+    m_sliceStride (align(createInfo.size, 256)) {
     
     VkBufferCreateInfo info;
     info.sType                 = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;

src/dxvk/dxvk_buffer_res.h

@@ -78,6 +78,14 @@ namespace dxvk {
       return m_handle;
     }
     
+    /**
+     * \brief Number of slices
+     * \returns Total slice count
+     */
+    VkDeviceSize sliceCount() const {
+      return m_sliceCount;
+    }
+    
     /**
      * \brief Map pointer
      * 
@@ -108,6 +116,7 @@ namespace dxvk {
     DxvkMemory        m_memory;
     VkBuffer          m_handle;
     
+    VkDeviceSize      m_sliceCount;
     VkDeviceSize      m_sliceLength;
     VkDeviceSize      m_sliceStride;
     

src/dxvk/dxvk_context.cpp

@@ -541,8 +541,7 @@ namespace dxvk {
   
   void DxvkContext::invalidateBuffer(const Rc<DxvkBuffer>& buffer) {
     // Allocate new backing resource
-    buffer->renameResource(
-      buffer->allocateResource());
+    buffer->rename(buffer->allocPhysicalSlice());
     
     // We also need to update all bindings that the buffer
     // may be bound to either directly or through views.

src/dxvk/dxvk_device.cpp

@@ -37,11 +37,12 @@ namespace dxvk {
   }
   
   
-  Rc<DxvkPhysicalBuffer> DxvkDevice::allocBufferResource(
+  Rc<DxvkPhysicalBuffer> DxvkDevice::allocPhysicalBuffer(
     const DxvkBufferCreateInfo& createInfo,
+          VkDeviceSize          sliceCount,
           VkMemoryPropertyFlags memoryType) {
     return new DxvkPhysicalBuffer(m_vkd,
-      createInfo, 1, *m_memory, memoryType);
+      createInfo, sliceCount, *m_memory, memoryType);
   }
   
   

src/dxvk/dxvk_device.h

@@ -101,14 +101,16 @@ namespace dxvk {
     }
     
     /**
-     * \brief Allocates buffer resource
+     * \brief Allocates a physical buffer
      * 
      * \param [in] createInfo Buffer create info
+     * \param [in] sliceCount Buffer slice count
      * \param [in] memoryType Memory property flags
      * \returns The buffer resource object
      */
-    Rc<DxvkPhysicalBuffer> allocBufferResource(
+    Rc<DxvkPhysicalBuffer> allocPhysicalBuffer(
       const DxvkBufferCreateInfo& createInfo,
+            VkDeviceSize          sliceCount,
             VkMemoryPropertyFlags memoryType);
     
     /**