Struct Grid 

pub struct Grid { /* private fields */ }

A hart’s view of an SPMD launch: its identity within n_harts participants.

The safety story of the reduction demo lives here. A kernel body, given a Grid, can obtain only its own disjoint slice of the input and its own output cell – it has no way to name another hart’s data, so cross-hart data races are unrepresentable in the (safe) kernel body. The small unsafe boundary that turns device addresses into slices is confined to this module.

Implementations

impl Grid

pub fn new(n_harts: u32) -> Self

Build from the current hart’s id and the number of participating harts.

pub fn hart(&self) -> u32

pub fn n_harts(&self) -> u32

pub fn active(&self) -> bool

Whether this hart participates (the launch runs every hart of the shire, so surplus harts opt out).

pub fn my_slice<'a, T>(&self, data: &'a [T]) -> &'a [T]

Borrow this hart’s disjoint sub-slice of data.

pub unsafe fn output_cell<'a, T>(&self, base: usize) -> &'a mut T

Borrow this hart’s own output cell from an array of one cache-line-padded T per hart based at device address base.

Safety

base must address at least n_harts * CACHE_LINE writable bytes of device memory. Disjointness across harts is guaranteed by construction (distinct hart ids map to distinct cache lines).