Re: [RFC][PATCH 1/2] sched: Extended scheduler time slice

On Thu, 6 Feb 2025 14:44:08 +0100
Sebastian Andrzej Siewior [off-list ref] 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