mmtk/util/heap/
accounting.rs

1use std::sync::atomic::AtomicUsize;
2use std::sync::atomic::Ordering;
3
4/// The struct is used for page usage.
5/// Both page resource and side metadata uses this struct to do page accounting.
6pub struct PageAccounting {
7    /// The reserved pages. This should be incremented when we are about to allocate pages.
8    /// Note this is different than quarantining address range. We do not count for quarantined
9    /// memory.
10    reserved: AtomicUsize,
11    /// The committed pages. This should be incremented when we successfully allocate pages from the OS.
12    committed: AtomicUsize,
13}
14
15impl PageAccounting {
16    pub fn new() -> Self {
17        Self {
18            reserved: AtomicUsize::new(0),
19            committed: AtomicUsize::new(0),
20        }
21    }
22
23    /// Inform of both reserving and committing a certain number of pages.
24    pub fn reserve_and_commit(&self, pages: usize) {
25        self.reserved.fetch_add(pages, Ordering::Relaxed);
26        self.committed.fetch_add(pages, Ordering::Relaxed);
27    }
28
29    /// Inform of reserving a certain number of pages. Usually this is called before attempting
30    /// to allocate memory.
31    pub fn reserve(&self, pages: usize) {
32        self.reserved.fetch_add(pages, Ordering::Relaxed);
33    }
34
35    /// Inform of clearing some reserved pages. This is used when we have reserved some pages but
36    /// the allocation cannot be satisfied. We can call this to clear the number of reserved pages,
37    /// so later we can reserve and attempt again.
38    pub fn clear_reserved(&self, pages: usize) {
39        let _prev = self.reserved.fetch_sub(pages, Ordering::Relaxed);
40        debug_assert!(_prev >= pages);
41    }
42
43    /// Inform of successfully committing a certain number of pages. This is used after we have reserved
44    /// pages and successfully allocated those memory.
45    pub fn commit(&self, pages: usize) {
46        self.committed.fetch_add(pages, Ordering::Relaxed);
47    }
48
49    /// Inform of releasing a certain number of pages. The number of pages will be deducted from
50    /// both reserved and committed pages.
51    pub fn release(&self, pages: usize) {
52        let _prev_reserved = self.reserved.fetch_sub(pages, Ordering::Relaxed);
53        debug_assert!(_prev_reserved >= pages);
54
55        let _prev_committed = self.committed.fetch_sub(pages, Ordering::Relaxed);
56        debug_assert!(_prev_committed >= pages);
57    }
58
59    /// Set both reserved and committed pages to zero. This is only used when we completely clear a space.
60    pub fn reset(&self) {
61        self.reserved.store(0, Ordering::Relaxed);
62        self.committed.store(0, Ordering::Relaxed);
63    }
64
65    pub fn get_reserved_pages(&self) -> usize {
66        self.reserved.load(Ordering::Relaxed)
67    }
68
69    pub fn get_committed_pages(&self) -> usize {
70        self.committed.load(Ordering::Relaxed)
71    }
72}
73
74impl Default for PageAccounting {
75    fn default() -> Self {
76        Self::new()
77    }
78}
mmtk/util/heap/accounting.rs

mmtk/util/heap/
accounting.rs
