Enum MemPolicy 

pub enum MemPolicy {
    Default,
    Bind(BTreeSet<usize>),
    Preferred(usize),
    Interleave(BTreeSet<usize>),
    Local,
    PreferredMany(BTreeSet<usize>),
    WeightedInterleave(BTreeSet<usize>),
}

NUMA memory placement policy for worker processes.

Applied via set_mempolicy(2) after fork, before the work loop. Maps to Linux MPOL_* constants. When Default, no syscall is made (inherits the parent’s policy).

Optional MpolFlags modify behavior (e.g. STATIC_NODES to keep the nodemask absolute across cpuset changes).

Variants

Default

Inherit the parent process’s memory policy (no syscall).

Bind(BTreeSet<usize>)

Allocate only from the specified NUMA nodes (MPOL_BIND).

Preferred(usize)

Prefer allocations from the specified node, falling back to others when the preferred node is full (MPOL_PREFERRED).

Interleave(BTreeSet<usize>)

Interleave allocations round-robin across the specified nodes (MPOL_INTERLEAVE).

Local

Prefer the nearest node to the CPU where the allocation occurs (MPOL_LOCAL). No nodemask.

PreferredMany(BTreeSet<usize>)

Prefer allocations from any of the specified nodes, falling back to others when all preferred nodes are full (MPOL_PREFERRED_MANY, kernel 5.15+).

WeightedInterleave(BTreeSet<usize>)

Weighted interleave across the specified nodes. Page distribution is proportional to per-node weights set via /sys/kernel/mm/mempolicy/weighted_interleave/nodeN (MPOL_WEIGHTED_INTERLEAVE, kernel 6.9+).

Implementations

impl MemPolicy

pub fn bind(nodes: impl IntoIterator<Item = usize>) -> Self

Construct a Bind policy from any iterator of NUMA node IDs.

Accepts arrays, ranges, Vec, BTreeSet, or any IntoIterator<Item = usize>.

pub const fn preferred(node: usize) -> Self

Construct a Preferred policy for a single NUMA node.

pub fn interleave(nodes: impl IntoIterator<Item = usize>) -> Self

Construct an Interleave policy from any iterator of NUMA node IDs.

Accepts arrays, ranges, Vec, BTreeSet, or any IntoIterator<Item = usize>.

pub fn preferred_many(nodes: impl IntoIterator<Item = usize>) -> Self

Construct a PreferredMany policy from any iterator of NUMA node IDs.

pub fn weighted_interleave(nodes: impl IntoIterator<Item = usize>) -> Self

Construct a WeightedInterleave policy from any iterator of NUMA node IDs.

pub fn node_set(&self) -> BTreeSet<usize>

NUMA node IDs referenced by this policy.

Returns the node set for Bind, Interleave, PreferredMany, and WeightedInterleave, a single-element set for Preferred, and an empty set for Default/Local.

pub fn validate(&self) -> Result<(), String>

Validate that this policy’s node set is non-empty where required.

Returns Err with a description when a node-set-bearing policy has an empty set. Each diagnostic names the offending variant, the constraint (“at least one NUMA node”), and the actionable fix — both the matching constructor and the recommended fallbacks for “I don’t want node-restricted placement” — so the operator sees the next mouse-click inline rather than having to cargo doc --open to discover the constructor menu. Mirrors the workers_pct rejection trailer at WorkSpec::resolve_workers_pct.

Trait Implementations

impl Clone for MemPolicy

fn clone(&self) -> MemPolicy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MemPolicy

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

Formats the value using the given formatter.

impl Default for MemPolicy

fn default() -> MemPolicy

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for MemPolicy

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for MemPolicy

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 MemPolicy

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl Serialize for MemPolicy

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for MemPolicy

impl StructuralPartialEq for MemPolicy