Struct WidthCosts 

pub struct WidthCosts { /* private fields */ }

Dispatch cost of one kind of token at the measured widths 2, 4 and 6.

The model: linear interpolation between the anchors, the value at width 2 below it, and above width 6 the width 6 value held flat (the Linux data at width 8 is below the width 6 value, so flat is conservative and simple). The model is evaluated once, when the value is built (new and flat are const), into a table of nanoseconds, so a lookup is an index. Width 1 never reaches the model: a token of one slot has no parallel section, see Exec::dispatch_cost.

Examples

use std::num::NonZeroUsize;
use std::time::Duration;
use threadteam::WidthCosts;

let us = Duration::from_micros;
let c = WidthCosts::new([us(3), us(2), us(1)]);
assert_eq!(c.at(NonZeroUsize::new(2).unwrap()), us(3));
assert_eq!(c.at(NonZeroUsize::new(3).unwrap()), Duration::from_nanos(2500));
assert_eq!(c.at(NonZeroUsize::new(12).unwrap()), us(1));
assert_eq!(c.min(), us(1));

Implementations

impl WidthCosts

pub const fn new(at_2_4_6: [Duration; 3]) -> Self

The costs measured at widths 2, 4 and 6.

pub const fn flat(cost: Duration) -> Self

The same cost at every anchor (the model of an unmeasured host).

pub fn at(&self, width: NonZeroUsize) -> Duration

The cost of a section of width participants, by the model above.

pub fn min(&self) -> Duration

The cheapest cost over all widths (the model is evaluated at every width, so this is right also for a table whose cost rises with width). A region whose serial estimate is below PAYS * min() pays at no width, which is the cheap rejection before a per-width search.

Trait Implementations

impl Clone for WidthCosts

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WidthCosts

impl Debug for WidthCosts

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

Formats the value using the given formatter.

impl Eq for WidthCosts

impl PartialEq for WidthCosts

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for WidthCosts