vkAllocateMemory

To allocate memory objects, call:

VkResult vkAllocateMemory(
    VkDevice device,
    const VkMemoryAllocateInfo* pAllocateInfo,
    const VkAllocationCallbacks* pAllocator,
    VkDeviceMemory* pMemory);

• device is the logical device that owns the memory.
• pAllocateInfo is a pointer to a VkMemoryAllocateInfo structure describing parameters of the allocation. A successfully returned allocation must use the requested parameters — no substitution is permitted by the implementation.
• pAllocator controls host memory allocation as described in the Memory Allocation chapter.
• pMemory is a pointer to a VkDeviceMemory handle in which information about the allocated memory is returned.

Allocations returned by vkAllocateMemory are guaranteed to meet any alignment requirement of the implementation. For example, if an implementation requires 128 byte alignment for images and 64 byte alignment for buffers, the device memory returned through this mechanism would be 128-byte aligned. This ensures that applications can correctly suballocate objects of different types (with potentially different alignment requirements) in the same memory object.

When memory is allocated, its contents are undefined:.

The maximum number of valid memory allocations that can exist simultaneously within a VkDevice may be restricted by implementation- or platform-dependent limits. The maxMemoryAllocationCount feature describes the number of allocations that can exist simultaneously before encountering these internal limits.

Some platforms may have a limit on the maximum size of a single allocation. For example, certain systems may fail to create allocations with a size greater than or equal to 4GB. Such a limit is implementation-dependent, and if such a failure occurs then the error VK_ERROR_OUT_OF_DEVICE_MEMORY must be returned. This limit is advertised in VkPhysicalDeviceMaintenance3Properties::maxMemoryAllocationSize.

The cumulative memory size allocated to a heap can be limited by the size of the specified heap. In such cases, allocated memory is tracked on a per-device and per-heap basis. Some platforms allow overallocation into other heaps. The overallocation behavior can be specified through the VK_AMD_memory_overallocation_behavior extension.

If the VkPhysicalDevicePageableDeviceLocalMemoryFeaturesEXT::pageableDeviceLocalMemory feature is enabled, memory allocations made from a heap that includes VK_MEMORY_HEAP_DEVICE_LOCAL_BIT in VkMemoryHeap::flagsmay be transparently moved to host-local memory allowing multiple applications to share device-local memory. If there is no space left in device-local memory when this new allocation is made, other allocations may be moved out transparently to make room. The operating system will determine which allocations to move to device-local memory or host-local memory based on platform-specific criteria. To help the operating system make good choices, the application should set the appropriate memory priority with VkMemoryPriorityAllocateInfoEXT and adjust it as necessary with vkSetDeviceMemoryPriorityEXT. Higher priority allocations will moved to device-local memory first.

Memory allocations made on heaps without the VK_MEMORY_HEAP_DEVICE_LOCAL_BIT property will not be transparently promoted to device-local memory by the operating system.