On Thu, 6 Feb 2025 14:44:08 +0100 Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > I did add a scheduling point in rt_spin_unlock() if LAZY was set and > based on few tests it was something between noise and worse. It seems > that "run to completion" is better than interrupt the kernel in the > middle whatever it is doing. "Don't preempt the lock owner" is already > handled by LAZY with the scheduling point on return to userland. Does that mean that PREEMPT_RT requires a non preempt method for SCHED_OTHER for SCHED_OTHER to not hit the issues that we were originally hitting? That is, with being able to preempt spin_locks in PREEMPT_RT, running a system with PREEMPT_RT in full preemption mode will still suffer performance issues against a non PREEMPT_RT running in full preemption mode? -- Steve
