Vulkan Memory Allocator
Classes | Typedefs | Functions
Layer 2 Allocating Memory

Classes

struct  VmaAllocationInfo
 Parameters of VmaAllocation objects, that can be retrieved using function vmaGetAllocationInfo(). More...
 
struct  VmaDefragmentationInfo
 Optional configuration parameters to be passed to function vmaDefragment(). More...
 
struct  VmaDefragmentationStats
 Statistics returned by function vmaDefragment(). More...
 

Typedefs

typedef struct VmaAllocationInfo VmaAllocationInfo
 Parameters of VmaAllocation objects, that can be retrieved using function vmaGetAllocationInfo(). More...
 
typedef struct VmaDefragmentationInfo VmaDefragmentationInfo
 Optional configuration parameters to be passed to function vmaDefragment(). More...
 
typedef struct VmaDefragmentationStats VmaDefragmentationStats
 Statistics returned by function vmaDefragment(). More...
 

Functions

VkResult vmaAllocateMemory (VmaAllocator allocator, const VkMemoryRequirements *pVkMemoryRequirements, const VmaMemoryRequirements *pVmaMemoryRequirements, VmaAllocation *pAllocation, VmaAllocationInfo *pAllocationInfo)
 General purpose memory allocation. More...
 
VkResult vmaAllocateMemoryForBuffer (VmaAllocator allocator, VkBuffer buffer, const VmaMemoryRequirements *pMemoryRequirements, VmaAllocation *pAllocation, VmaAllocationInfo *pAllocationInfo)
 
VkResult vmaAllocateMemoryForImage (VmaAllocator allocator, VkImage image, const VmaMemoryRequirements *pMemoryRequirements, VmaAllocation *pAllocation, VmaAllocationInfo *pAllocationInfo)
 Function similar to vmaAllocateMemoryForBuffer(). More...
 
void vmaFreeMemory (VmaAllocator allocator, VmaAllocation allocation)
 Frees memory previously allocated using vmaAllocateMemory(), vmaAllocateMemoryForBuffer(), or vmaAllocateMemoryForImage(). More...
 
void vmaGetAllocationInfo (VmaAllocator allocator, VmaAllocation allocation, VmaAllocationInfo *pAllocationInfo)
 Returns current information about specified allocation. More...
 
void vmaSetAllocationUserData (VmaAllocator allocator, VmaAllocation allocation, void *pUserData)
 Sets pUserData in given allocation to new value. More...
 
VkResult vmaMapMemory (VmaAllocator allocator, VmaAllocation allocation, void **ppData)
 
void vmaUnmapMemory (VmaAllocator allocator, VmaAllocation allocation)
 
void vmaUnmapPersistentlyMappedMemory (VmaAllocator allocator)
 Unmaps persistently mapped memory of types that is HOST_COHERENT and DEVICE_LOCAL. More...
 
VkResult vmaMapPersistentlyMappedMemory (VmaAllocator allocator)
 Maps back persistently mapped memory of types that is HOST_COHERENT and DEVICE_LOCAL. More...
 
VkResult vmaDefragment (VmaAllocator allocator, VmaAllocation *pAllocations, size_t allocationCount, VkBool32 *pAllocationsChanged, const VmaDefragmentationInfo *pDefragmentationInfo, VmaDefragmentationStats *pDefragmentationStats)
 Compacts memory by moving allocations. More...
 

Detailed Description

Typedef Documentation

◆ VmaAllocationInfo

Parameters of VmaAllocation objects, that can be retrieved using function vmaGetAllocationInfo().

◆ VmaDefragmentationInfo

Optional configuration parameters to be passed to function vmaDefragment().

◆ VmaDefragmentationStats

Statistics returned by function vmaDefragment().

Function Documentation

◆ vmaAllocateMemory()

VkResult vmaAllocateMemory ( VmaAllocator  allocator,
const VkMemoryRequirements *  pVkMemoryRequirements,
const VmaMemoryRequirements pVmaMemoryRequirements,
VmaAllocation *  pAllocation,
VmaAllocationInfo pAllocationInfo 
)

General purpose memory allocation.

Parameters
[out]pAllocationHandle to allocated memory.
[out]pAllocationInfoOptional. Information about allocated memory. It can be later fetched using function vmaGetAllocationInfo().

You should free the memory using vmaFreeMemory().

It is recommended to use vmaAllocateMemoryForBuffer(), vmaAllocateMemoryForImage(), vmaCreateBuffer(), vmaCreateImage() instead whenever possible.

◆ vmaAllocateMemoryForBuffer()

VkResult vmaAllocateMemoryForBuffer ( VmaAllocator  allocator,
VkBuffer  buffer,
const VmaMemoryRequirements pMemoryRequirements,
VmaAllocation *  pAllocation,
VmaAllocationInfo pAllocationInfo 
)
Parameters
[out]pAllocationHandle to allocated memory.
[out]pAllocationInfoOptional. Information about allocated memory. It can be later fetched using function vmaGetAllocationInfo().

You should free the memory using vmaFreeMemory().

◆ vmaAllocateMemoryForImage()

VkResult vmaAllocateMemoryForImage ( VmaAllocator  allocator,
VkImage  image,
const VmaMemoryRequirements pMemoryRequirements,
VmaAllocation *  pAllocation,
VmaAllocationInfo pAllocationInfo 
)

Function similar to vmaAllocateMemoryForBuffer().

◆ vmaDefragment()

VkResult vmaDefragment ( VmaAllocator  allocator,
VmaAllocation *  pAllocations,
size_t  allocationCount,
VkBool32 *  pAllocationsChanged,
const VmaDefragmentationInfo pDefragmentationInfo,
VmaDefragmentationStats pDefragmentationStats 
)

Compacts memory by moving allocations.

Parameters
pAllocationsArray of allocations that can be moved during this compation.
allocationCountNumber of elements in pAllocations and pAllocationsChanged arrays.
[out]pAllocationsChangedArray of boolean values that will indicate whether matching allocation in pAllocations array has been moved. This parameter is optional. Pass null if you don't need this information.
pDefragmentationInfoConfiguration parameters. Optional - pass null to use default values.
[out]pDefragmentationStatsStatistics returned by the function. Optional - pass null if you don't need this information.
Returns
VK_SUCCESS if completed, VK_INCOMPLETE if succeeded but didn't make all possible optimizations because limits specified in pDefragmentationInfo have been reached, negative error code in case of error.

This function works by moving allocations to different places (different VkDeviceMemory objects and/or different offsets) in order to optimize memory usage. Only allocations that are in pAllocations array can be moved. All other allocations are considered nonmovable in this call. Basic rules:

  • Only allocations made in memory types that have VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT flag can be compacted. You may pass other allocations but it makes no sense - these will never be moved.
  • You may pass allocations made with VMA_MEMORY_REQUIREMENT_OWN_MEMORY_BIT but it makes no sense - they will never be moved.
  • Both allocations made with or without VMA_MEMORY_REQUIREMENT_PERSISTENT_MAP_BIT flag can be compacted. If not persistently mapped, memory will be mapped temporarily inside this function if needed, so it shouldn't be mapped by you for the time of this call.
  • You must not pass same VmaAllocation object multiple times in pAllocations array.

The function also frees empty VkDeviceMemory blocks.

After allocation has been moved, its VmaAllocationInfo::deviceMemory and/or VmaAllocationInfo::offset changes. You must query them again using vmaGetAllocationInfo() if you need them.

If an allocation has been moved, data in memory is copied to new place automatically, but if it was bound to a buffer or an image, you must destroy that object yourself, create new one and bind it to the new memory pointed by the allocation. You must use vkDestroyBuffer(), vkDestroyImage(), vkCreateBuffer(), vkCreateImage() for that purpose and NOT vmaDestroyBuffer(), vmaDestroyImage(), vmaCreateBuffer(), vmaCreateImage()! Example:

VkDevice device = ...;
VmaAllocator allocator = ...;
std::vector<VkBuffer> buffers = ...;
std::vector<VmaAllocation> allocations = ...;

std::vector<VkBool32> allocationsChanged(allocations.size());
vmaDefragment(allocator, allocations.data(), allocations.size(), allocationsChanged.data(), nullptr, nullptr);

for(size_t i = 0; i < allocations.size(); ++i)
{
    if(allocationsChanged[i])
    {
        VmaAllocationInfo allocInfo;
        vmaGetAllocationInfo(allocator, allocations[i], &allocInfo);

        vkDestroyBuffer(device, buffers[i], nullptr);

        VkBufferCreateInfo bufferInfo = ...;
        vkCreateBuffer(device, &bufferInfo, nullptr, &buffers[i]);

        .// You can make dummy call to vkGetBufferMemoryRequirements here to silence validation layer warning.

        vkBindBufferMemory(device, buffers[i], allocInfo.deviceMemory, allocInfo.offset);
    }
}

This function may be time-consuming, so you shouldn't call it too often (like every frame or after every resource creation/destruction), but rater you can call it on special occasions (like when reloading a game level, when you just destroyed a lot of objects).

◆ vmaFreeMemory()

void vmaFreeMemory ( VmaAllocator  allocator,
VmaAllocation  allocation 
)

Frees memory previously allocated using vmaAllocateMemory(), vmaAllocateMemoryForBuffer(), or vmaAllocateMemoryForImage().

◆ vmaGetAllocationInfo()

void vmaGetAllocationInfo ( VmaAllocator  allocator,
VmaAllocation  allocation,
VmaAllocationInfo pAllocationInfo 
)

Returns current information about specified allocation.

◆ vmaMapMemory()

VkResult vmaMapMemory ( VmaAllocator  allocator,
VmaAllocation  allocation,
void **  ppData 
)

Feel free to use vkMapMemory on these memory blocks on you own if you want, but just for convenience and to make sure correct offset and size is always specified, usage of vmaMapMemory() / vmaUnmapMemory() is recommended.

Do not use it on memory allocated with VMA_MEMORY_REQUIREMENT_PERSISTENT_MAP_BIT as multiple maps to same VkDeviceMemory is illegal.

◆ vmaMapPersistentlyMappedMemory()

VkResult vmaMapPersistentlyMappedMemory ( VmaAllocator  allocator)

Maps back persistently mapped memory of types that is HOST_COHERENT and DEVICE_LOCAL.

See vmaUnmapPersistentlyMappedMemory().

After this call VmaAllocationInfo::pMappedData of some allocation may have value different than before calling vmaUnmapPersistentlyMappedMemory().

◆ vmaSetAllocationUserData()

void vmaSetAllocationUserData ( VmaAllocator  allocator,
VmaAllocation  allocation,
void *  pUserData 
)

Sets pUserData in given allocation to new value.

◆ vmaUnmapMemory()

void vmaUnmapMemory ( VmaAllocator  allocator,
VmaAllocation  allocation 
)

◆ vmaUnmapPersistentlyMappedMemory()

void vmaUnmapPersistentlyMappedMemory ( VmaAllocator  allocator)

Unmaps persistently mapped memory of types that is HOST_COHERENT and DEVICE_LOCAL.

This is optional performance optimization. On Windows you should call it before every call to vkQueueSubmit and vkQueuePresent. After which you can remap the allocations again using vmaMapPersistentlyMappedMemory(). This is because of the internal behavior of WDDM. Example:

vmaUnmapPersistentlyMappedMemory(allocator);
vkQueueSubmit(...)
vmaMapPersistentlyMappedMemory(allocator);

After this call VmaAllocationInfo::pMappedData of some allocations may become null.

This call is reference-counted. Memory is mapped again after you call vmaMapPersistentlyMappedMemory() same number of times that you called vmaUnmapPersistentlyMappedMemory().