On Tue, Feb 11, 2025 at 09:21:38AM +0100, Sebastian Andrzej Siewior wrote: > So with LAZY_PREEMPT (not that one that was merged upstream, its > predecessor) we had a counter similar to the preemption counter. On each > rt_spin_lock() the counter was incremented, on each rt_spin_unlock() the > counter was decremented. Once the counter hit zero and the lazy preempt > flag was set (which was only set on schedule requests by SCHED_OTHER > tasks), we scheduled. > This improved the performance as we didn't schedule() while holding a > spinlock_t and then bump into the same lock in the next task. > > We don't follow this behaviour exactly today.
I think I send some hackery Mike's way to implement that at some point. IIRC it wasn't an obvious win. Anyway its not too hard to do.
