Struct LeaseGenLine 

pub struct LeaseGenLine {
    pub lease_generation: AtomicU64,
    /* private fields */
}

Second header line: the drainer-lease GENERATION, alone on its own cache line. Bumped only on lease claim / takeover / release and on epoch ticks - all rare events - so a merge drainer’s per-pop lease verification is one load of a line that is NEVER written in steady state (an L1 hit with zero coherence traffic), instead of loads on the first header line that every SharedCounter push fetch_adds. Measured on the Zen3 KVM guest: per-pop loads of that stamp-hot line cost a cache-to-cache transfer each (~130 ns) and tripled the merge rungs.

Fields

lease_generation: AtomicU64