tcontract_exec/
width.rs

1/// Cost model for choosing a barrier-free partition width from the work.
2///
3/// `T_par(k) = entry_base_ns + entry_per_thread_ns * k + serial_ns / k` for
4/// `k > 1`; work below `serial_below_ns` always runs serially. The defaults
5/// are provisional values from `experiments/rayon-entry` (M5 Max,
6/// 2026-09-29); kernels replace them with their own measured policy.
7///
8/// # Examples
9///
10/// ```
11/// let p = tcontract_exec::WidthPolicy::default();
12/// assert_eq!(p.serial_below_ns, 50_000.0);
13/// ```
14#[derive(Clone, Copy, Debug, PartialEq)]
15pub struct WidthPolicy {
16    /// Estimated serial time below which work never leaves the caller.
17    pub serial_below_ns: f64,
18    /// Fixed part of the pool entry cost.
19    pub entry_base_ns: f64,
20    /// Entry cost added per participating worker.
21    pub entry_per_thread_ns: f64,
22}
23
24impl Default for WidthPolicy {
25    fn default() -> Self {
26        Self {
27            serial_below_ns: 50_000.0,
28            entry_base_ns: 5_000.0,
29            entry_per_thread_ns: 5_000.0,
30        }
31    }
32}
tcontract_exec/width.rs

tcontract_exec/
width.rs
