Struct Zone 

pub struct Zone {

    pub zone_type: ZoneType,
    pub base: PhysAddr,
    pub page_count: usize,
    pub present_pages: usize,
    pub span_pages: usize,
    pub allocated: usize,
    pub reserved_pages: usize,
    pub lowmem_reserve_pages: usize,
    pub watermark_min: usize,
    pub watermark_low: usize,
    pub watermark_high: usize,
    pub segment_count: usize,
    pub segment_capacity: usize,
    pub segments: *mut ZoneSegment,
}

Memory zone with buddy allocator free lists

Fields

zone_type: ZoneType

Zone type

base: PhysAddr

Base physical address of this zone

page_count: usize

Total number of managed pages in this zone.

present_pages: usize

Pages reported as usable RAM by the boot memory map for this zone.

span_pages: usize

Total address span covered by this zone metadata, in pages.

Unlike page_count, this includes holes and is kept for diagnostics.

allocated: usize

Number of allocated pages

reserved_pages: usize

Pages removed from management during boot reservations.

lowmem_reserve_pages: usize

Hard reserve kept available for lower zones or emergency paths.

watermark_min: usize

Watermark below which this zone should be avoided when possible.

watermark_low: usize

Advisory low watermark for diagnostics and future reclaim hooks.

watermark_high: usize

Advisory high watermark for diagnostics and future reclaim hooks.

segment_count: usize

Number of populated contiguous segments in this zone.

segment_capacity: usize

Total number of segment slots reserved for this zone.

segments: *mut ZoneSegment

Independently managed contiguous segments inside this zone.

Implementations

impl Zone

pub const fn new(zone_type: ZoneType) -> Self

Create a new empty zone

pub fn segments(&self) -> &[ZoneSegment]

Returns the reserved segment storage as a slice.

pub fn segments_mut(&mut self) -> &mut [ZoneSegment]

Returns the reserved segment storage as a mutable slice.

pub fn clear_segments(&mut self)

Reset the zone’s segment storage metadata.

pub fn contains_address(&self, addr: PhysAddr) -> bool

Check if an address is within this zone

pub fn available_pages(&self) -> usize

Get number of available (free) pages

pub fn free_list_count(&self, order: u8) -> usize

Count the number of free blocks at a given order.

Walks the buddy free list. Safe because we only read the next link from the per-frame crate::memory::frame::MetaSlot (not from mapped page bytes).

pub fn free_list_count_for(&self, order: u8, migratetype: Migratetype) -> usize

Count the number of free blocks at a given order for one migratetype.

pub fn free_pages_by_migratetype(&self) -> [usize; 2]

Returns the total free pages by migratetype across all orders.

pub fn free_pages_at_or_above_order(&self, order: u8) -> usize

Returns the number of free pages currently available in blocks of at least order.

This is the relevant numerator for fragmentation analysis of an allocation request at order: pages on smaller free lists exist, but cannot satisfy that request without prior coalescing.

pub fn fragmentation_score( &self, order: u8, cached_order0_pages: usize, ) -> usize

Returns a simple fragmentation score for order, expressed as a percentage.

0 means all currently free pages are still usable for an allocation of that order. 100 means all free pages are trapped in blocks smaller than the requested order. cached_order0_pages accounts for pages parked in per-CPU caches, which behave like order-0 fragments until drained.

pub fn largest_free_order(&self) -> Option<u8>

Returns the largest order that currently has at least one free block.

Trait Implementations

impl Send for Zone