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VK_NV_dedicated_allocation

Other Extension Metadata

Last Modified Date

2016-05-31

IP Status

No known IP claims.

Contributors
  • Jeff Bolz, NVIDIA

Description

This extension allows device memory to be allocated for a particular buffer or image resource, which on some devices can significantly improve the performance of that resource. Normal device memory allocations must support memory aliasing and sparse binding, which could interfere with optimizations like framebuffer compression or efficient page table usage. This is important for render targets and very large resources, but need not (and probably should not) be used for smaller resources that can benefit from suballocation.

This extension adds a few small structures to resource creation and memory allocation: a new structure that flags whether am image/buffer will have a dedicated allocation, and a structure indicating the image or buffer that an allocation will be bound to.

New Structures

New Enum Constants

  • VK_NV_DEDICATED_ALLOCATION_EXTENSION_NAME
  • VK_NV_DEDICATED_ALLOCATION_SPEC_VERSION
  • Extending VkStructureType:
    • VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_BUFFER_CREATE_INFO_NV
    • VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_IMAGE_CREATE_INFO_NV
    • VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_MEMORY_ALLOCATE_INFO_NV

Examples

    // Create an image with
    // VkDedicatedAllocationImageCreateInfoNV::dedicatedAllocation
    // set to VK_TRUE

    VkDedicatedAllocationImageCreateInfoNV dedicatedImageInfo =
    {
        .sType = VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_IMAGE_CREATE_INFO_NV,
        .pNext = NULL,
        .dedicatedAllocation = VK_TRUE,
    };

    VkImageCreateInfo imageCreateInfo =
    {
        .sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
        .pNext = &dedicatedImageInfo
        // Other members set as usual
    };

    VkImage image;
    VkResult result = vkCreateImage(
        device,
        &imageCreateInfo,
        NULL,               // pAllocator
        &image);

    VkMemoryRequirements memoryRequirements;
    vkGetImageMemoryRequirements(
        device,
        image,
        &memoryRequirements);

    // Allocate memory with VkDedicatedAllocationMemoryAllocateInfoNV::image
    // pointing to the image we are allocating the memory for

    VkDedicatedAllocationMemoryAllocateInfoNV dedicatedInfo =
    {
        .sType = VK_STRUCTURE_TYPE_DEDICATED_ALLOCATION_MEMORY_ALLOCATE_INFO_NV,
        .pNext = NULL,
        .image = image,
        .buffer = VK_NULL_HANDLE,
    };

    VkMemoryAllocateInfo memoryAllocateInfo =
    {
        .sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO,
        .pNext = &dedicatedInfo,
        .allocationSize = memoryRequirements.size,
        .memoryTypeIndex = FindMemoryTypeIndex(memoryRequirements.memoryTypeBits),
    };

    VkDeviceMemory memory;
    vkAllocateMemory(
        device,
        &memoryAllocateInfo,
        NULL,               // pAllocator
        &memory);

    // Bind the image to the memory

    vkBindImageMemory(
        device,
        image,
        memory,
        0);

Version History

  • Revision 1, 2016-05-31 (Jeff Bolz)
    • Internal revisions