Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

Peter Zijlstra
2017-07-12T11:55:13Z

On Tue, Jul 11, 2017 at 11:09:31AM -0700, Paul E. McKenney wrote:
> On Tue, Jul 11, 2017 at 06:34:22PM +0200, Peter Zijlstra wrote:

> > But I think we can at the very least do this; it only gets called from
> > kernel/sched/idle.c and both callsites have IRQs explicitly disabled by
> > that point.
> >
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 51d4c3acf32d..dccf2dc8155a 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -843,13 +843,8 @@ static void rcu_eqs_enter(bool user)
> > */
> > void rcu_idle_enter(void)
> > {
> > - unsigned long flags;
> > -
> > - local_irq_save(flags);
>
> With this addition, I am all for it:
>
> RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_idle_enter() invoked with irqs enabled!!!");
>
> If you are OK with this addition, may I please have your Signed-off-by?

Sure,

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

>
> > rcu_eqs_enter(false);
> > - local_irq_restore(flags);
> > }
> > -EXPORT_SYMBOL_GPL(rcu_idle_enter);
> >
> > #ifdef CONFIG_NO_HZ_FULL
> > /**
> >
>