Re: [PATCH v2 7/9] sched: define TIF_ALLOW_RESCHED

Steven Rostedt
2023-10-18T18:00:43Z

On Wed, 18 Oct 2023 10:55:02 -0700
"Paul E. McKenney" <paulmck@kernel.org> wrote:

> > If everything becomes PREEMPT_RCU, then the above should be able to be
> > turned into just:
> >
> > if (!disable_irq)
> > local_irq_disable();
> >
> > rcu_momentary_dyntick_idle();
> >
> > if (!disable_irq)
> > local_irq_enable();
> >
> > And no cond_resched() is needed.
>
> Even given that CONFIG_PREEMPT_RCU=n still exists, the fact that
> run_osnoise() is running in kthread context with preemption and everything
> else enabled (am I right?), then the change you suggest should work fine.

There's a user space option that lets you run that loop with preemption and/or
interrupts disabled.

>
> > > Again. There is no non-preemtible RCU with this model, unless I'm
> > > missing something important here.
> >
> > Daniel?
>
> But very happy to defer to Daniel. ;-)

But Daniel could also correct me ;-)

-- Steve