VK_KHR_dedicated_allocation
Other Extension Metadata
Last Modified Date
2017-09-05
IP Status
No known IP claims.
Contributors
- Jeff Bolz, NVIDIA
- Faith Ekstrand, Intel
Description
This extension enables resources to be bound to a dedicated allocation,
rather than suballocated.
For any particular resource, applications can query whether a dedicated
allocation is recommended, in which case using a dedicated allocation may
improve the performance of access to that resource.
Normal device memory allocations must support multiple resources per
allocation, memory aliasing and sparse binding, which could interfere with
some optimizations.
Applications should query the implementation for when a dedicated allocation
may be beneficial by adding a VkMemoryDedicatedRequirementsKHR
structure to the pNext
chain of the VkMemoryRequirements2
structure passed as the pMemoryRequirements
parameter of a call to
vkGetBufferMemoryRequirements2
or vkGetImageMemoryRequirements2
.
Certain external handle types and external images or buffers may also
depend on dedicated allocations on implementations that associate image or
buffer metadata with OS-level memory objects.
This extension adds a two small structures to memory requirements querying and memory allocation: a new structure that flags whether an image/buffer should have a dedicated allocation, and a structure indicating the image or buffer that an allocation will be bound to.
Promotion to Vulkan 1.1
All functionality in this extension is included in core Vulkan 1.1, with the KHR suffix omitted. The original type, enum and command names are still available as aliases of the core functionality.
New Structures
- Extending VkMemoryAllocateInfo:
- Extending VkMemoryRequirements2:
New Enum Constants
VK_KHR_DEDICATED_ALLOCATION_EXTENSION_NAME
VK_KHR_DEDICATED_ALLOCATION_SPEC_VERSION
- Extending VkStructureType:
VK_STRUCTURE_TYPE_MEMORY_DEDICATED_ALLOCATE_INFO_KHR
VK_STRUCTURE_TYPE_MEMORY_DEDICATED_REQUIREMENTS_KHR
Examples
// Create an image with a dedicated allocation based on the
// implementation's preference
VkImageCreateInfo imageCreateInfo =
{
// Image creation parameters
};
VkImage image;
VkResult result = vkCreateImage(
device,
&imageCreateInfo,
NULL, // pAllocator
&image);
VkMemoryDedicatedRequirementsKHR dedicatedRequirements =
{
.sType = VK_STRUCTURE_TYPE_MEMORY_DEDICATED_REQUIREMENTS_KHR,
.pNext = NULL,
};
VkMemoryRequirements2 memoryRequirements =
{
.sType = VK_STRUCTURE_TYPE_MEMORY_REQUIREMENTS_2,
.pNext = &dedicatedRequirements,
};
const VkImageMemoryRequirementsInfo2 imageRequirementsInfo =
{
.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_REQUIREMENTS_INFO_2,
.pNext = NULL,
.image = image
};
vkGetImageMemoryRequirements2(
device,
&imageRequirementsInfo,
&memoryRequirements);
if (dedicatedRequirements.prefersDedicatedAllocation) {
// Allocate memory with VkMemoryDedicatedAllocateInfoKHR::image
// pointing to the image we are allocating the memory for
VkMemoryDedicatedAllocateInfoKHR dedicatedInfo =
{
.sType = VK_STRUCTURE_TYPE_MEMORY_DEDICATED_ALLOCATE_INFO_KHR,
.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);
} else {
// Take the normal memory sub-allocation path
}
Version History
- Revision 1, 2017-02-27 (James Jones)
- Copy content from VK_NV_dedicated_allocation
- Add some references to external object interactions to the overview.
- Revision 2, 2017-03-27 (Faith Ekstrand)
- Rework the extension to be query-based
- Revision 3, 2017-07-31 (Faith Ekstrand)
- Clarify that memory objects allocated with VkMemoryDedicatedAllocateInfoKHR can only have the specified resource bound and no others.