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

[Steven Rostedt]

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