diff options
Diffstat (limited to 'src/sched.rs')
-rw-r--r-- | src/sched.rs | 79 |
1 files changed, 76 insertions, 3 deletions
diff --git a/src/sched.rs b/src/sched.rs index 67188c57..7675dbc2 100644 --- a/src/sched.rs +++ b/src/sched.rs @@ -46,6 +46,11 @@ mod sched_linux_like { pub type CloneCb<'a> = Box<dyn FnMut() -> isize + 'a>; + /// CpuSet represent a bit-mask of CPUs. + /// CpuSets are used by sched_setaffinity and + /// sched_getaffinity for example. + /// + /// This is a wrapper around `libc::cpu_set_t`. #[repr(C)] #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)] pub struct CpuSet { @@ -53,37 +58,70 @@ mod sched_linux_like { } impl CpuSet { + /// Create a new and empty CpuSet. pub fn new() -> CpuSet { CpuSet { cpu_set: unsafe { mem::zeroed() }, } } + /// Test to see if a CPU is in the CpuSet. + /// `field` is the CPU id to test pub fn is_set(&self, field: usize) -> Result<bool> { - if field >= 8 * mem::size_of::<libc::cpu_set_t>() { + if field >= CpuSet::count() { Err(Error::Sys(Errno::EINVAL)) } else { Ok(unsafe { libc::CPU_ISSET(field, &self.cpu_set) }) } } + /// Add a CPU to CpuSet. + /// `field` is the CPU id to add pub fn set(&mut self, field: usize) -> Result<()> { - if field >= 8 * mem::size_of::<libc::cpu_set_t>() { + if field >= CpuSet::count() { Err(Error::Sys(Errno::EINVAL)) } else { Ok(unsafe { libc::CPU_SET(field, &mut self.cpu_set) }) } } + /// Remove a CPU from CpuSet. + /// `field` is the CPU id to remove pub fn unset(&mut self, field: usize) -> Result<()> { - if field >= 8 * mem::size_of::<libc::cpu_set_t>() { + if field >= CpuSet::count() { Err(Error::Sys(Errno::EINVAL)) } else { Ok(unsafe { libc::CPU_CLR(field, &mut self.cpu_set) }) } } + + /// Return the maximum number of CPU in CpuSet + pub fn count() -> usize { + 8 * mem::size_of::<libc::cpu_set_t>() + } } + /// `sched_setaffinity` set a thread's CPU affinity mask + /// ([`sched_setaffinity(2)`](http://man7.org/linux/man-pages/man2/sched_setaffinity.2.html)) + /// + /// `pid` is the thread ID to update. + /// If pid is zero, then the calling thread is updated. + /// + /// The `cpuset` argument specifies the set of CPUs on which the thread + /// will be eligible to run. + /// + /// # Example + /// + /// Binding the current thread to CPU 0 can be done as follows: + /// + /// ```rust,no_run + /// use nix::sched::{CpuSet, sched_setaffinity}; + /// use nix::unistd::Pid; + /// + /// let mut cpu_set = CpuSet::new(); + /// cpu_set.set(0); + /// sched_setaffinity(Pid::from_raw(0), &cpu_set); + /// ``` pub fn sched_setaffinity(pid: Pid, cpuset: &CpuSet) -> Result<()> { let res = unsafe { libc::sched_setaffinity( @@ -96,6 +134,41 @@ mod sched_linux_like { Errno::result(res).map(drop) } + /// `sched_getaffinity` get a thread's CPU affinity mask + /// ([`sched_getaffinity(2)`](http://man7.org/linux/man-pages/man2/sched_getaffinity.2.html)) + /// + /// `pid` is the thread ID to check. + /// If pid is zero, then the calling thread is checked. + /// + /// Returned `cpuset` is the set of CPUs on which the thread + /// is eligible to run. + /// + /// # Example + /// + /// Checking if the current thread can run on CPU 0 can be done as follows: + /// + /// ```rust,no_run + /// use nix::sched::sched_getaffinity; + /// use nix::unistd::Pid; + /// + /// let cpu_set = sched_getaffinity(Pid::from_raw(0)).unwrap(); + /// if cpu_set.is_set(0).unwrap() { + /// println!("Current thread can run on CPU 0"); + /// } + /// ``` + pub fn sched_getaffinity(pid: Pid) -> Result<CpuSet> { + let mut cpuset = CpuSet::new(); + let res = unsafe { + libc::sched_getaffinity( + pid.into(), + mem::size_of::<CpuSet>() as libc::size_t, + &mut cpuset.cpu_set, + ) + }; + + Errno::result(res).and(Ok(cpuset)) + } + pub fn clone( mut cb: CloneCb, stack: &mut [u8], |