Re: [PATCH v2] EXP rcu: Move expedited grace period (GP) work to RT kthread_worker

[Steven Rostedt]

On Fri, 8 Apr 2022 06:21:03 -0400
Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote:

> > +       default !PREEMPT_RT && NR_CPUS <= 32  
> 
> What is the benefit of turning it off on PREEMPT_RT, even if
> PREEMPT_RT does not use expedited GPs much post-boot? I would think in
> the future if PREEMPT_RT ever uses expedited GPs, they would want this
> feature even more. I'd rather be future-proof now as I don't see any
> advantages of disabling it on !PREEMPT_RT (And a drawback that the fix
> won't apply to those systems). Also will keep the config simple.

The default kthread priority is 1. This should not affect PREEMPT_RT, as
PREEMPT_RT users are usually more concerned by the performance of their
higher priority tasks. Priority 1 is not considered an issue.

I do not see why PREEMPT_RT is special here. Why was it singled out?

-- Steve