Enum glommio::Placement

pub enum Placement {
    Unbound,
    Fenced(CpuSet),
    Fixed(usize),
}

Specifies a policy by which LocalExecutorBuilder selects CPUs.

Placement is used to bind LocalExecutors to a set of CPUs via preconfigured policies designed to address a variety of use cases.

Example

Some Placements allow manually filtering available CPUs via a CpuSet, such as MaxSpread. The following would place shards on four CPUs (a.k.a. hyper-threads) that are on NUMA node 0 and have an even numbered package ID according to their CpuLocation. The selection aims to achieve a high degree of separation between the CPUs in terms of machine topology. Each LocalExecutor would be bound to a single CPU.

use glommio::{CpuSet, LocalExecutorBuilder, Placement};

let cpus = CpuSet::online()
    .expect("Err: please file an issue with glommio")
    .filter(|l| l.numa_node == 0)
    .filter(|l| l.package % 2 == 0);

LocalExecutorBuilder::new(Placement::Fenced(cpus))
    .spawn(|| async move {
        // ... important stuff ...
    })
    .unwrap()
    .join();

Variants

Unbound

The Unbound variant creates a LocalExecutors that are not bound to any CPU.

Fenced(CpuSet)

The Fenced variant binds the LocalExecutor to the set of CPUs specified by CpuSet. With an unfiltered CPU set returned by CpuSet::online, this is similar to using Unbound with the distinction that bringing additional CPUs online will not allow the executor to run on the newly available CPUs.

Errors

If the provided CpuSet contains no CPUs, the builder will fail.

Fixed(usize)

The LocalExecutor is bound to the CPU specified by Fixed.

Errors

LocalExecutorBuilder will return Result::Err if the CPU doesn’t exist.

Implementations

impl Placement

pub fn generate_cpu_set(self) -> Result<CpuSetGenerator, ()>

Probe the topology of the system and materialize this Placement into a CpuSet

Trait Implementations

impl Clone for Placement

fn clone(&self) -> Placement

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Placement

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<Placement> for PoolPlacement

fn from(placement: Placement) -> Self

Converts to this type from the input type.

impl Hash for Placement

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Placement

fn eq(&self, other: &Placement) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Placement

impl StructuralPartialEq for Placement