pub const DISK_LINE_HYSTERESIS_PERCENT: u64 = 5;Expand description
Hysteresis under the disk line (owner 2026-09-28): once the line trips, the pressure holds until the disk is this many points BELOW it (80 → 75). Without it a disk that stays over 80 % because of packs — not cache — made every tick drop every lazy segment but the live one, in every store, while write-back kept refilling them: the cache rewrote and threw away up to a segment per store per tick.