1use crate::process::Pid;
2use crate::{backend, io};
3
4/// `CpuSet` represents a bit-mask of CPUs.
5///
6/// `CpuSet`s are used by [`sched_setaffinity`] and [`sched_getaffinity`], for
7/// example.
8///
9/// # References
10/// - [Linux]
11///
12/// [Linux]: https://man7.org/linux/man-pages/man3/CPU_SET.3.html
13/// [`sched_setaffinity`]: crate::process::sched_setaffinity
14/// [`sched_getaffinity`]: crate::process::sched_getaffinity
15#[repr(C)]
16#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
17pub struct CpuSet {
18 cpu_set: backend::process::types::RawCpuSet,
19}
20
21impl CpuSet {
22 /// The maximum number of CPU in `CpuSet`.
23 pub const MAX_CPU: usize = backend::process::types::CPU_SETSIZE;
24
25 /// Create a new and empty `CpuSet`.
26 #[inline]
27 pub fn new() -> Self {
28 Self {
29 cpu_set: backend::process::types::raw_cpu_set_new(),
30 }
31 }
32
33 /// Test to see if a CPU is in the `CpuSet`.
34 ///
35 /// `field` is the CPU id to test.
36 #[inline]
37 pub fn is_set(&self, field: usize) -> bool {
38 backend::process::cpu_set::CPU_ISSET(field, &self.cpu_set)
39 }
40
41 /// Add a CPU to `CpuSet`.
42 ///
43 /// `field` is the CPU id to add.
44 #[inline]
45 pub fn set(&mut self, field: usize) {
46 backend::process::cpu_set::CPU_SET(field, &mut self.cpu_set)
47 }
48
49 /// Remove a CPU from `CpuSet`.
50 ///
51 /// `field` is the CPU id to remove.
52 #[inline]
53 pub fn unset(&mut self, field: usize) {
54 backend::process::cpu_set::CPU_CLR(field, &mut self.cpu_set)
55 }
56
57 /// Count the number of CPUs set in the `CpuSet`.
58 #[cfg(linux_kernel)]
59 #[inline]
60 pub fn count(&self) -> u32 {
61 backend::process::cpu_set::CPU_COUNT(&self.cpu_set)
62 }
63
64 /// Zeroes the `CpuSet`.
65 #[inline]
66 pub fn clear(&mut self) {
67 backend::process::cpu_set::CPU_ZERO(&mut self.cpu_set)
68 }
69}
70
71impl Default for CpuSet {
72 #[inline]
73 fn default() -> Self {
74 Self::new()
75 }
76}
77
78/// `sched_setaffinity(pid, cpuset)`—Set a thread's CPU affinity mask.
79///
80/// `pid` is the thread ID to update. If pid is `None`, then the current thread
81/// is updated.
82///
83/// The `CpuSet` argument specifies the set of CPUs on which the thread will be
84/// eligible to run.
85///
86/// # References
87/// - [Linux]
88///
89/// [Linux]: https://man7.org/linux/man-pages/man2/sched_setaffinity.2.html
90#[inline]
91pub fn sched_setaffinity(pid: Option<Pid>, cpuset: &CpuSet) -> io::Result<()> {
92 backend::process::syscalls::sched_setaffinity(pid, &cpuset.cpu_set)
93}
94
95/// `sched_getaffinity(pid)`—Get a thread's CPU affinity mask.
96///
97/// `pid` is the thread ID to check. If pid is `None`, then the current thread
98/// is checked.
99///
100/// Returns the set of CPUs on which the thread is eligible to run.
101///
102/// # References
103/// - [Linux]
104///
105/// [Linux]: https://man7.org/linux/man-pages/man2/sched_getaffinity.2.html
106#[inline]
107pub fn sched_getaffinity(pid: Option<Pid>) -> io::Result<CpuSet> {
108 let mut cpuset: CpuSet = CpuSet::new();
109 backend::process::syscalls::sched_getaffinity(pid, &mut cpuset.cpu_set).and(res:Ok(cpuset))
110}
111
112/// `sched_getcpu()`—Get the CPU that the current thread is currently on.
113///
114/// # References
115/// - [Linux]
116/// - [DragonFly BSD]
117///
118/// [Linux]: https://man7.org/linux/man-pages/man2/sched_getcpu.2.html
119/// [DragonFly BSD]: https://man.dragonflybsd.org/?command=sched_getcpu&section=2
120// FreeBSD added `sched_getcpu` in 13.0.
121#[cfg(any(linux_kernel, target_os = "dragonfly"))]
122#[inline]
123pub fn sched_getcpu() -> usize {
124 backend::process::syscalls::sched_getcpu()
125}
126