FMallocBinned3

Navigation

API > API/Runtime > API/Runtime/Core

Optimized virtual memory allocator.

MallocBinned3 supports two types of allocations - large and small pool allocation:

For small pool allocation MallocBinned3 reserves contiguous range of virtual memory (a Pool) for each allocation size (a Bin). These Pools can be adjacent to each other in memory if BINNED3_USE_SEPARATE_VM_PER_POOL is set to 0. By default each Pool reserves 1 GB of address space, unless USE_512MB_MAX_MEMORY_PER_BLOCK_SIZE is defined to 1. Each Pool commits and decommits reserved memory in Blocks. Each Block is equal to at least one memory page in it's size. A Block contains N Bins in a way to minimize the tail memory waste. For example 16 bytes bins fit inside 4KB memory page without any waste; i.e. one Block for 16 byte Bins contains 256 bins. However 736 bytes Bin uses two 4KB pages in it's Block to minimize memory waste. Each Pool manages it's Blocks allocation via a Bit Tree (BlocksAllocatedBits\BlocksExhaustedBits members). And every Block manages it's Bins via a number of additional data structures - FPoolInfoSmall and FFreeBlock. FFreeBlock is an in-place header for the Block that's stored at the end of each block and contains info on number of free Bins and index of the next free Block if any Memory is allocated top down in a Block

For large allocations we go directly to OS, unless UE_MB3_USE_CACHED_PAGE_ALLOCATOR_FOR_LARGE_ALLOCS is defined to 1 Each allocation is handled via FPlatformVirtualMemoryBlock and information about it is stored in FPoolInfoFPoolInfo stores the original allocation size and how much memory was committed by the OS in case we need to realloc that allocation and there's enough tail waste to do that in place All FPoolInfo are stored in the PoolHashBucket and HashBucketFreeList

Syntax

class FMallocBinned3 : public TMallocBinnedCommon< FMallocBinned3, - 28672)/4096), >  
Copy full snippet

class FMallocBinned3 : public TMallocBinnedCommon< FMallocBinned3, - 28672)/4096), >

Inheritance Hierarchy

• FExec → FMalloc → FMallocBinnedCommonBase → TMallocBinnedCommon → FMallocBinned3
• FUseSystemMallocForNew → FMalloc → FMallocBinnedCommonBase → TMallocBinnedCommon → FMallocBinned3

Constructors

Destructors

Structs

Constants

Variables

Public

Protected

Functions

Public

Overridden from FMalloc

Static