trueno/tiling/
prefetch.rs

1//! Prefetch locality hints for cache optimization.
2
3use super::geometry::{TcbGeometry, TcbLevel};
4
5/// Prefetch locality hint
6#[derive(Debug, Clone, Copy)]
7pub enum PrefetchLocality {
8    /// Non-temporal (streaming, evict soon)
9    NonTemporal,
10    /// L3 cache
11    T2,
12    /// L2 cache
13    T1,
14    /// L1 cache (highest priority)
15    T0,
16}
17
18/// Calculate optimal prefetch distance based on tile geometry and cache level
19///
20/// Per Ding & Kennedy (2004): distance = memory_latency / compute_time_per_iter
21#[must_use]
22pub fn optimal_prefetch_distance(geometry: &TcbGeometry, level: TcbLevel) -> usize {
23    // Approximate cycles per micro-tile
24    let compute_cycles = geometry.m as usize * geometry.n as usize * geometry.k as usize / 8;
25
26    // Memory latency in cycles (approximate for modern x86)
27    let mem_latency = match level {
28        TcbLevel::Micro => 4,  // L1: ~4 cycles
29        TcbLevel::Midi => 12,  // L2: ~12 cycles
30        TcbLevel::Macro => 40, // L3: ~40 cycles
31    };
32
33    // Distance = latency / compute_time, minimum 1
34    (mem_latency / compute_cycles.max(1)).max(1)
35}
trueno/tiling/prefetch.rs

trueno/tiling/
prefetch.rs
