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//! Linux-specific helpers
#[cfg(doc)]
use crate::cpu::binding::CpuBindingFlags;
use crate::{
cpu::cpuset::CpuSet,
errors::{self, HybridError, RawHwlocError},
path::{self, PathError},
topology::Topology,
};
#[allow(unused)]
#[cfg(test)]
use similar_asserts::assert_eq;
use std::{ops::Deref, path::Path};
// This file is rustdoc-visible so we must provide a substitute for
// linux-specific libc entities when people run rustdoc on Windows.
#[cfg(target_os = "linux")]
use libc::pid_t;
#[cfg(all(doc, not(target_os = "linux")))]
#[allow(non_camel_case_types)]
struct pid_t;
/// # Linux-specific helpers
///
/// This includes helpers for manipulating Linux kernel cpumap files, and hwloc
/// equivalents of the Linux `sched_setaffinity` and `sched_getaffinity` system
/// calls.
//
// --- Implementation details ---
//
// Upstream docs: https://hwloc.readthedocs.io/en/v2.9/group__hwlocality__linux.html
impl Topology {
/// Bind a thread `tid` on cpus given in `set`
///
/// `set` can be a `&'_ CpuSet` or a `BitmapRef<'_, CpuSet>`.
///
/// The behavior is exactly the same as the Linux `sched_setaffinity` system
/// call, but uses a hwloc [`CpuSet`].
///
/// This is equivalent to calling [`bind_process_cpu()`] with the [`THREAD`]
/// binding flag.
///
/// [`bind_process_cpu()`]: Topology::bind_process_cpu()
/// [`THREAD`]: CpuBindingFlags::THREAD
#[allow(clippy::missing_errors_doc)]
#[doc(alias = "hwloc_linux_set_tid_cpubind")]
pub fn bind_tid_cpu(
&self,
tid: pid_t,
set: impl Deref<Target = CpuSet>,
) -> Result<(), RawHwlocError> {
/// Polymorphized version of this function (avoids generics code bloat)
fn polymorphized(self_: &Topology, tid: pid_t, set: &CpuSet) -> Result<(), RawHwlocError> {
// SAFETY: - Topology is trusted to contain a valid ptr (type invariant)
// - Bitmap is trusted to contain a valid ptr (type invariant)
// - hwloc ops are trusted not to modify *const parameters
// - TID cannot be validated (think TOCTOU), but hwloc should be
// able to handle an invalid TID
errors::call_hwloc_int_normal("hwloc_linux_set_tid_cpubind", || unsafe {
hwlocality_sys::hwloc_linux_set_tid_cpubind(self_.as_ptr(), tid, set.as_ptr())
})
.map(std::mem::drop)
}
polymorphized(self, tid, &set)
}
/// Current binding of thread `tid`.
///
/// Returns the [`CpuSet`] of PUs which the thread was last bound to.
///
/// The behavior is exactly the same as the Linux `sched_getaffinity` system
/// call, but uses a hwloc [`CpuSet`].
///
/// This is equivalent to calling [`process_cpu_binding()`] with the
/// [`THREAD`] binding flag.
///
/// [`process_cpu_binding()`]: Topology::process_cpu_binding()
/// [`THREAD`]: CpuBindingFlags::THREAD
#[allow(clippy::missing_errors_doc)]
#[doc(alias = "hwloc_linux_get_tid_cpubind")]
pub fn tid_cpu_binding(&self, tid: pid_t) -> Result<CpuSet, RawHwlocError> {
let mut set = CpuSet::new();
// SAFETY: - Topology is trusted to contain a valid ptr (type invariant)
// - Bitmap is trusted to contain a valid ptr (type invariant)
// - hwloc ops are trusted not to modify *const parameters
// - hwloc ops are trusted to keep *mut parameters in a
// valid state unless stated otherwise
// - TID cannot be validated (think TOCTOU), but hwloc should be
// able to handle an invalid TID
errors::call_hwloc_int_normal("hwloc_linux_get_tid_cpubind", || unsafe {
hwlocality_sys::hwloc_linux_get_tid_cpubind(self.as_ptr(), tid, set.as_mut_ptr())
})
.map(|_| set)
}
/// Last physical CPU where thread `tid` ran.
///
/// Indicates the PU which the thread last ran on, as a singleton [`CpuSet`].
///
/// This is equivalent to calling [`last_process_cpu_location()`] with the
/// [`THREAD`] binding flag.
///
/// [`last_process_cpu_location()`]: Topology::last_process_cpu_location()
/// [`THREAD`]: CpuBindingFlags::THREAD
#[allow(clippy::missing_errors_doc)]
#[doc(alias = "hwloc_linux_get_tid_last_cpu_location")]
pub fn tid_last_cpu_location(&self, tid: pid_t) -> Result<CpuSet, RawHwlocError> {
let mut set = CpuSet::new();
// SAFETY: - Topology is trusted to contain a valid ptr (type invariant)
// - Bitmap is trusted to contain a valid ptr (type invariant)
// - hwloc ops are trusted not to modify *const parameters
// - hwloc ops are trusted to keep *mut parameters in a
// valid state unless stated otherwise
// - TID cannot be validated (think TOCTOU), but hwloc should be
// able to handle an invalid TID
errors::call_hwloc_int_normal("hwloc_linux_get_tid_last_cpu_location", || unsafe {
hwlocality_sys::hwloc_linux_get_tid_last_cpu_location(
self.as_ptr(),
tid,
set.as_mut_ptr(),
)
})
.map(|_| set)
}
/// Convert a linux kernel cpumask file path into a hwloc bitmap set.
///
/// Might be used when reading CPU sets from sysfs attributes such as
/// topology and caches for processors, or local_cpus for devices.
///
/// Note that this function ignores the [HWLOC_FSROOT environment
/// variable](https://hwloc.readthedocs.io/en/v2.9/envvar.html).
///
/// # Errors
///
/// - [`ContainsNul`] if `path` contains NUL chars.
/// - [`NotUnicode`] if `path` contains non-Unicode data
///
/// # Example
///
#[cfg_attr(target_os = "linux", doc = "```rust")]
#[cfg_attr(not(target_os = "linux"), doc = "```rust,ignore")]
/// # use hwlocality::{topology::Topology, object::types::ObjectType};
/// #
/// # let topology = Topology::test_instance();
/// #
/// use eyre::eyre;
///
/// // Read cpuset of first core via Linux sysfs
/// let core_set = topology
/// .read_path_as_cpumask("/sys/devices/system/cpu/cpu0/topology/core_cpus")?;
///
/// // Check that the hwloc version is consistent
/// assert_eq!(
/// core_set,
/// topology
/// .objects_with_type(ObjectType::Core)
/// .next()
/// .ok_or_else(|| eyre!("Linux systesm should have CPU cores"))?
/// .cpuset()
/// .ok_or_else(|| eyre!("CPU cores should have cpusets"))?
/// );
/// #
/// # Ok::<(), eyre::Report>(())
/// ```
///
/// [`ContainsNul`]: PathError::ContainsNul
/// [`NotUnicode`]: PathError::NotUnicode
#[doc(alias = "hwloc_linux_read_path_as_cpumask")]
pub fn read_path_as_cpumask(
&self,
path: impl AsRef<Path>,
) -> Result<CpuSet, HybridError<PathError>> {
/// Polymorphized version of this function (avoids generics code bloat)
fn polymorphized(path: &Path) -> Result<CpuSet, HybridError<PathError>> {
let path = path::make_hwloc_path(path)?;
let mut set = CpuSet::new();
// SAFETY: - Path is trusted to contain a valid C string (type invariant)
// - Bitmap is trusted to contain a valid ptr (type invariant)
// - hwloc ops are trusted not to modify *const parameters
// - hwloc ops are trusted to keep *mut parameters in a
// valid state unless stated otherwise
errors::call_hwloc_int_normal("hwloc_linux_read_path_as_cpumask", || unsafe {
hwlocality_sys::hwloc_linux_read_path_as_cpumask(path.borrow(), set.as_mut_ptr())
})
.map_err(HybridError::Hwloc)?;
Ok(set)
}
polymorphized(path.as_ref())
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::object::types::ObjectType;
#[allow(unused)]
use similar_asserts::assert_eq;
#[test]
fn read_path_as_cpumask() {
let topology = Topology::test_instance();
// Read cpuset of first core via Linux sysfs
let core_set = topology
.read_path_as_cpumask("/sys/devices/system/cpu/cpu0/topology/core_cpus")
.unwrap();
// Compare with hwloc result
assert_eq!(
core_set,
topology
.objects_with_type(ObjectType::Core)
.next()
.unwrap()
.cpuset()
.unwrap()
);
}
}