Struct kalloc::buddy::BuddySystem

#[repr(C)]
pub struct BuddySystem<P> { /* fields omitted */ }

Buddy System Allocator Structure.

Memory Layout

         bitmap_begin          page_begin          page_end
              |                    |                   |
              v                    v                   v
+-------------+--------+-----------+-------------------+
| this struct | bitmap | (padding) | 2^max_order pages |
+-------------+--------+-----------+-------------------+
                                   ^
                                   |      
                   page_begin is a multiple of P

Implementations

impl<P: Unsigned + PowerOfTwo> BuddySystem<P>

pub unsafe fn build(begin: usize, end: usize) -> Result<&'static mut Self, ()>

Construct a buddy system allocator at memory [begin, end) with specific page size.

Notice that it guarantees safety only if the access to [begin, end) is safe and self is a static variable.

pub unsafe fn alloc1(&mut self, order: usize) -> *mut u8

Alloccate memory by order.

pub unsafe fn free(&mut self, ptr: *mut u8, order: usize) -> usize

Free the block of memory starting from ptr with specific order. Return the order of the freed page after merging possible buddy pages.

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

Allocate memory specified by layout.

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

Free the block of memory starting from ptr with specific layout.

pub unsafe fn check(&self)

Check the properties maintained by buddy system.

• 1-nodes that don’t have any 1-node child are allocated chunks.
• Root 0-nodes and 0-nodes whose father is 1-node and buddy is 1-node are free chunks.
• Children of any 0-node must be also 0-nodes.