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  3. FGPUDefragAllocator

FGPUDefragAllocator

Simple best fit allocator, splitting and coalescing whenever/ wherever possible.

API > API/Runtime > API/Runtime/RHI

Simple best fit allocator, splitting and coalescing whenever/ wherever possible. NOT THREAD-SAFE.

  • uses TMap to find memory chunk given a Pointer (potentially colliding with malloc/ free from main thread)
  • uses separate linked list for free allocations, assuming that relatively few free chunks due to coalescing
   
Name FGPUDefragAllocator
Type class
Header File /Engine/Source/Runtime/RHI/Public/GPUDefragAllocator.h
Include Path #include "GPUDefragAllocator.h"

Syntax

class FGPUDefragAllocator

Constructors

Name Remarks Include Path Unreal Specifiers

FGPUDefragAllocator()

 Constructor, zero initializing all member variables GPUDefragAllocator.h  

Destructors

Name Remarks Include Path Unreal Specifiers

virtual ~FGPUDefragAllocator()

   GPUDefragAllocator.h  

Classes

Name Remarks
FMemoryChunk Contains information of a single allocation or free block.

Structs

Name Remarks
FMemoryLayoutElement  
FRelocationStats Container for allocator relocation stats.
FSettings Container for allocator settings.

Enums

Public

Name Remarks
EMemoryElementType  

Typedefs

Name Type Remarks Include Path
FRequestList TDoubleLinkedList< FAsyncReallocationRequest * >   GPUDefragAllocator.h
FRequestNode TDoubleLinkedList< FAsyncReallocationRequest * >::TDoubleLinkedListNode   GPUDefragAllocator.h
memsize_t int64 Allocated memory in uint8s. GPUDefragAllocator.h

Functions

Public

Name Remarks Include Path Unreal Specifiers

virtual void * Allocate ( int64 AllocationSize,
int32 Alignment,
TStatId InStat,
bool bAllowFailure
)

 Allocate physical memory. GPUDefragAllocator.h  

void Benchmark ( int32 MinChunkSize,
int32 MaxChunkSize,
float FreeRatio,
float LockRatio,
bool bFullDefrag,
bool bSaveImages,
const TCHAR* Filename
)

 Performs a benchmark of the allocator and outputs the result to the log. GPUDefragAllocator.h  

void BlockOnAsyncReallocation ( FAsyncReallocationRequest* Request
)

 Blocks the calling thread until the specified request has been completed. GPUDefragAllocator.h  

void CancelAsyncReallocation ( FAsyncReallocationRequest* Request,
const void* CurrentBaseAddress
)

 Cancels the specified reallocation request. GPUDefragAllocator.h  

void DefragmentMemory ( FRelocationStats& Stats
)

 Fully defragments the memory and blocks until it's done. GPUDefragAllocator.h  

void DumpAllocs ( FOutputDevice& Ar
)

 Dump allocation information. GPUDefragAllocator.h  

bool FinishAllRelocations()

 Blocks the calling thread until all relocations and reallocations that were initiated by Tick() have completed. GPUDefragAllocator.h  

virtual void Free ( void* Pointer
)

 Frees allocation associated with the specified Pointer. GPUDefragAllocator.h  

int64 GetAllocatedSize ( void* Pointer
)

 Returns the amount of memory allocated for the specified address. GPUDefragAllocator.h  

int32 GetAllocationAlignment()

   GPUDefragAllocator.h  

uint32 GetBlockedCycles()

 Returns the amount of time blocked by a platform fence since the beginning of the last call to Tick(), in appCycles. GPUDefragAllocator.h  

EMemoryElementType GetChunkType ( FMemoryChunk* Chunk
) const

   GPUDefragAllocator.h  

int32 GetLargestAvailableAllocation ( int32* OutNumFreeChunks
)

 Scans the free chunks and returns the largest size you can allocate. GPUDefragAllocator.h  

void GetMemoryLayout ( TArray< FMemoryLayoutElement >& MemoryLayout
)

   GPUDefragAllocator.h  

virtual void GetMemoryStats ( int64& OutAllocatedMemorySize,
int64& OutAvailableMemorySize,
int64& OutPendingMemoryAdjustment,
int64& OutPaddingWasteSize
)

 Retrieves allocation stats. GPUDefragAllocator.h  

void GetSettings ( FSettings& OutSettings
)

 Returns the current allocator settings. GPUDefragAllocator.h  

bool GetTextureMemoryVisualizeData ( FColor* TextureData,
int32 SizeX,
int32 SizeY,
int32 Pitch,
const int32 PixelSize
)

 Fills a texture with to visualize the texture pool memory. GPUDefragAllocator.h  

int64 GetTotalSize()

   GPUDefragAllocator.h  

void * GetUserPayload ( const void* Pointer
)

 Returns the user payload for an FMemoryChunk GPUDefragAllocator.h  

bool InBenchmarkMode()

 Returns whether we're in benchmark mode or not. GPUDefragAllocator.h  

virtual void Initialize ( uint8* InMemoryBase,
int64 InMemorySize
)

   GPUDefragAllocator.h  

virtual void Initialize ( uint8* InMemoryBase,
int64 InMemorySize,
int32 InAllocationAlignment
)

 Initialize this allocator with a preallocated block of memory. GPUDefragAllocator.h  

bool IsInitialized()

 Returns whether allocator has been initialized. GPUDefragAllocator.h  

bool IsValidPoolMemory ( const void* Pointer
) const

   GPUDefragAllocator.h  

virtual void Lock ( const void* Pointer
)

 Locks an FMemoryChunk GPUDefragAllocator.h  

void * Reallocate ( void* OldBaseAddress,
int64 NewSize
)

 Tries to reallocate texture memory in-place (without relocating), by adjusting the base address of the allocation but keeping the end address the same. GPUDefragAllocator.h  

void SetSettings ( const FSettings& InSettings
)

 Sets new allocator settings. GPUDefragAllocator.h  

void SetUserPayload ( const void* Pointer,
void* UserPayload
)

 Sets the user payload for an FMemoryChunk GPUDefragAllocator.h  

virtual int32 Tick ( FRelocationStats& Stats,
bool bPanicDefrag
)

 Partially defragments the memory and tries to process all async reallocation requests at the same time. GPUDefragAllocator.h  

virtual void Unlock ( const void* Pointer
)

 Unlocks an FMemoryChunk GPUDefragAllocator.h  

Protected

Name Remarks Include Path Unreal Specifiers

FMemoryChunk * AllocateChunk ( FMemoryChunk* FreeChunk,
int64 AllocationSize,
bool bAsync,
bool bDoValidation
)

 Marks the specified chunk as 'allocated' and updates tracking variables. GPUDefragAllocator.h  

void BlockOnFence()

 Blocks the calling thread until the current sync fence has been completed. GPUDefragAllocator.h  

void BlockOnSyncIndex ( uint32 SyncIndex
)

 Blocks the calling thread until the specified sync index has been completed. GPUDefragAllocator.h  

bool CanRelocate ( const FMemoryChunk* Chunk
) const

 Returns true if the specified chunk is allowed to relocate at this time. GPUDefragAllocator.h  

void CheckForErrors ( bool bCheckSortedFreeList
)

 Checks the int32ernal state for errors. (Slow)Checks the internal state for errors. (Slow) GPUDefragAllocator.h  

void Coalesce ( FMemoryChunk* FreedChunk
)

 Merges any adjacent free chunks into the specified free chunk. GPUDefragAllocator.h  

FMemoryChunk * FindAdjacent ( FMemoryChunk* UsedChunk,
bool bAnyChunkType
)

 Defrag helper function. Checks if the specified allocation fits within the adjacent free chunk(s). GPUDefragAllocator.h  
Searches for an allocated chunk that would fit within the specified free chunk. GPUDefragAllocator.h  

FMemoryChunk * FindAny ( FMemoryChunk* FreeChunk
)

 Searches for an allocated chunk that would fit within the specified free chunk. GPUDefragAllocator.h  

void FreeChunk ( FMemoryChunk* Chunk
)

 Marks the specified chunk as 'free' and updates tracking variables. GPUDefragAllocator.h  

void FullDefragmentation ( FRelocationStats& Stats
)

 Performs a full defrag and ignores all reallocation requests. GPUDefragAllocator.h  

uint32 GetCurrentSyncIndex()

 Returns the sync index to be completed by the next call to FinishAllRelocations(). GPUDefragAllocator.h  

FMemoryChunk * Grow ( FMemoryChunk* Chunk,
int64 GrowAmount
)

 Tries to immediately grow a memory chunk by moving the base address, without relocating any memory. GPUDefragAllocator.h  

void InsertFence()

 Inserts a platform fence and updates the allocator sync index to match. GPUDefragAllocator.h  

void LinkFreeChunk ( FMemoryChunk* Chunk
)

 Frees the passed in chunk and coalesces adjacent free chunks into 'Chunk' if possible. GPUDefragAllocator.h  

void PartialDefragmentationDownshift ( FRelocationStats& Stats,
double StartTime
)

 Performs a partial defrag by shifting down memory to fill holes, in a brute-force manner. GPUDefragAllocator.h  

void PartialDefragmentationFast ( FRelocationStats& Stats,
double StartTime
)

 Performs a partial defrag doing fast checks only. Adjacency and freelist walk. GPUDefragAllocator.h  

void PartialDefragmentationSlow ( FRelocationStats& Stats,
double StartTime
)

 Performs a partial defrag doing slow all chunk search to find used chunks to move that are surrounded by other used chunks That a freechunk walk won't find. GPUDefragAllocator.h  

void PlatformBlockOnFence ( uint64 Fence
)

 Blocks the calling thread until all relocations initiated before the fence was added has been fully completed. GPUDefragAllocator.h  

bool PlatformCanRelocate ( const void* Source,
void* UserPayload
) const

 Allows each platform to decide whether an allocation can be relocated at this time. GPUDefragAllocator.h  
Inserts a fence to synchronize relocations. GPUDefragAllocator.h  

void PlatformNotifyReallocationFinished ( FAsyncReallocationRequest* FinishedRequest,
void* UserPayload
)

 Notifies the platform that an async reallocation request has been completed. GPUDefragAllocator.h  

void PlatformRelocate ( void* Dest,
const void* Source,
int64 Size,
void* UserPayload
)

 Copy memory from one location to another. GPUDefragAllocator.h  

void Relocate ( FRelocationStats& Stats,
FMemoryChunk* Dest,
int64 DestOffset,
const void* Source,
int64 Size,
void* UserPayload
)

 Copy memory from one location to another. GPUDefragAllocator.h  

FMemoryChunk * RelocateAllowed ( FMemoryChunk* FreeChunk,
FMemoryChunk* UsedChunk
)

 Performs a partial defrag while trying to process any pending async reallocation requests. GPUDefragAllocator.h  
Initiates an async relocation of an allocated chunk into a free chunk. GPUDefragAllocator.h  

FMemoryChunk * Shrink ( FMemoryChunk* Chunk,
int64 ShrinkAmount
)

 Immediately shrinks a memory chunk by moving the base address, without relocating any memory. GPUDefragAllocator.h  

void SortFreeList ( int32& NumFreeChunks,
int64& LargestFreeChunk
)

 Sorts the freelist based on increasing base address. GPUDefragAllocator.h  

void Split ( FMemoryChunk* BaseChunk,
int64 FirstSize
)

 Split allocation into two, first chunk being used and second being available. GPUDefragAllocator.h  

Static

Name Remarks Include Path Unreal Specifiers

static bool IsAligned ( const volatile void* Ptr,
const uint32 Alignment
)

   GPUDefragAllocator.h  

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