C Specification
If the pNext
chain of VkMemoryAllocateInfo includes a
VkMemoryAllocateFlagsInfo
structure, then that structure includes
flags and a device mask controlling how many instances of the memory will be
allocated.
The VkMemoryAllocateFlagsInfo
structure is defined as:
// Provided by VK_VERSION_1_1
typedef struct VkMemoryAllocateFlagsInfo {
VkStructureType sType;
const void* pNext;
VkMemoryAllocateFlags flags;
uint32_t deviceMask;
} VkMemoryAllocateFlagsInfo;
Members
-
sType
is a VkStructureType value identifying this structure. -
pNext
isNULL
or a pointer to a structure extending this structure. -
flags
is a bitmask of VkMemoryAllocateFlagBits controlling the allocation. -
deviceMask
is a mask of physical devices in the logical device, indicating that memory must be allocated on each device in the mask, ifVK_MEMORY_ALLOCATE_DEVICE_MASK_BIT
is set inflags
.
Description
If VK_MEMORY_ALLOCATE_DEVICE_MASK_BIT
is not set, the number of
instances allocated depends on whether
VK_MEMORY_HEAP_MULTI_INSTANCE_BIT
is set in the memory heap.
If VK_MEMORY_HEAP_MULTI_INSTANCE_BIT
is set, then memory is allocated
for every physical device in the logical device (as if deviceMask
has
bits set for all device indices).
If VK_MEMORY_HEAP_MULTI_INSTANCE_BIT
is not set, then a single
instance of memory is allocated (as if deviceMask
is set to one).
On some implementations, allocations from a multi-instance heap may consume
memory on all physical devices even if the deviceMask
excludes some
devices.
If VkPhysicalDeviceGroupProperties::subsetAllocation
is
VK_TRUE
, then memory is only consumed for the devices in the device
mask.
Note
In practice, most allocations on a multi-instance heap will be allocated across all physical devices. Unicast allocation support is an optional optimization for a minority of allocations. |
Document Notes
For more information, see the Vulkan Specification
This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.