Struct axalloc::GlobalAllocator

pub struct GlobalAllocator { /* private fields */ }

The global allocator used by ArceOS.

It combines a ByteAllocator and a PageAllocator into a simple two-level allocator: firstly tries allocate from the byte allocator, if there is no memory, asks the page allocator for more memory and adds it to the byte allocator.

Currently, TlsfByteAllocator is used as the byte allocator, while BitmapPageAllocator is used as the page allocator.

Implementations

impl GlobalAllocator

pub const fn new() -> Self

Creates an empty GlobalAllocator.

pub const fn name(&self) -> &'static str

Returns the name of the allocator.

pub fn init(&self, start_vaddr: usize, size: usize)

Initializes the allocator with the given region.

It firstly adds the whole region to the page allocator, then allocates a small region (32 KB) to initialize the byte allocator. Therefore, the given region must be larger than 32 KB.

pub fn add_memory(&self, start_vaddr: usize, size: usize) -> AllocResult

Add the given region to the allocator.

It will add the whole region to the byte allocator.

pub fn alloc(&self, layout: Layout) -> AllocResult<NonNull<u8>>

Allocate arbitrary number of bytes. Returns the left bound of the allocated region.

It firstly tries to allocate from the byte allocator. If there is no memory, it asks the page allocator for more memory and adds it to the byte allocator.

align_pow2 must be a power of 2, and the returned region bound will be aligned to it.

pub fn dealloc(&self, pos: NonNull<u8>, layout: Layout)

Gives back the allocated region to the byte allocator.

The region should be allocated by alloc, and align_pow2 should be the same as the one used in alloc. Otherwise, the behavior is undefined.

pub fn alloc_pages( &self, num_pages: usize, align_pow2: usize ) -> AllocResult<usize>

Allocates contiguous pages.

It allocates num_pages pages from the page allocator.

align_pow2 must be a power of 2, and the returned region bound will be aligned to it.

pub fn dealloc_pages(&self, pos: usize, num_pages: usize)

Gives back the allocated pages starts from pos to the page allocator.

The pages should be allocated by alloc_pages, and align_pow2 should be the same as the one used in alloc_pages. Otherwise, the behavior is undefined.

pub fn used_bytes(&self) -> usize

Returns the number of allocated bytes in the byte allocator.

pub fn available_bytes(&self) -> usize

Returns the number of available bytes in the byte allocator.

pub fn used_pages(&self) -> usize

Returns the number of allocated pages in the page allocator.

pub fn available_pages(&self) -> usize

Returns the number of available pages in the page allocator.

Trait Implementations

impl GlobalAlloc for GlobalAllocator

unsafe fn alloc(&self, layout: Layout) -> *mut u8

Allocate memory as described by the given layout.

unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout)

Deallocate the block of memory at the given ptr pointer with the given layout.

unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8

Behaves like alloc, but also ensures that the contents are set to zero before being returned.

unsafe fn realloc( &self, ptr: *mut u8, layout: Layout, new_size: usize ) -> *mut u8

Shrink or grow a block of memory to the given new_size in bytes. The block is described by the given ptr pointer and layout.