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:
typedef struct VkMemoryAllocateFlagsInfo {
VkStructureType sType;
const void* pNext;
VkMemoryAllocateFlags flags;
uint32_t deviceMask;
} VkMemoryAllocateFlagsInfo;
or the equivalent
typedef VkMemoryAllocateFlagsInfo VkMemoryAllocateFlagsInfoKHR;
Members
-
sType
is the type of this structure. -
pNext
isNULL
or a pointer to an extension-specific 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. |
See Also
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.
Copyright
Copyright (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.