Re: [PATCH 8/8] Call tick_check_idle before __irq_enter

Peter Zijlstra
2010-10-18T09:15:58Z

On Sun, 2010-10-17 at 17:05 +0800, Yong Zhang wrote:
> On Mon, Oct 04, 2010 at 05:03:23PM -0700, Venkatesh Pallipadi wrote:
> > diff --git a/kernel/softirq.c b/kernel/softirq.c
> > index 267f7b7..6bb7e19 100644
> > --- a/kernel/softirq.c
> > +++ b/kernel/softirq.c
> > @@ -296,10 +296,16 @@ void irq_enter(void)
> >
> > rcu_irq_enter();
> > if (idle_cpu(cpu) && !in_interrupt()) {
> > - __irq_enter();
> > + /*
> > + * Prevent raise_softirq from needlessly waking up ksoftirqd
> > + * here, as softirq will be serviced on return from interrupt.
> > + */
> > + local_bh_disable();
> > tick_check_idle(cpu);
> > - } else
> > - __irq_enter();
> > + local_bh_enable();
>
> _local_bh_enable()
>
> local_bh_enable() could invoke do_softirq().

This seems to indeed cure that explosion.. Thanks!