Re: [patch V4 part 1 03/36] sched: Clean up scheduler_ipi()

Peter Zijlstra
2020-05-06T15:33:24Z

On Wed, May 06, 2020 at 02:37:19PM +0200, Alexandre Chartre wrote:
> On 5/5/20 3:16 PM, Thomas Gleixner wrote:
> > @@ -650,6 +655,16 @@ static inline bool got_nohz_idle_kick(vo
> > return false;
> > }
> > +static void nohz_csd_func(void *info)
> > +{
> > + struct rq *rq = info;
> > +
> > + if (got_nohz_idle_kick()) {
> > + rq->idle_balance = 1;
> > + raise_softirq_irqoff(SCHED_SOFTIRQ);
> > + }
> > +}
> > +
> > #else /* CONFIG_NO_HZ_COMMON */
> > static inline bool got_nohz_idle_kick(void)

> > #ifdef CONFIG_NO_HZ_COMMON
> > rq->last_blocked_load_update_tick = jiffies;
> > atomic_set(&rq->nohz_flags, 0);
> > +
> > + rq_csd_init(rq, &rq->nohz_csd, nohz_csd_func);
> > #endif
> > #endif /* CONFIG_SMP */
> > hrtick_rq_init(rq);
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -10009,12 +10009,11 @@ static void kick_ilb(unsigned int flags)
> > return;
> > /*
> > - * Use smp_send_reschedule() instead of resched_cpu().
> > - * This way we generate a sched IPI on the target CPU which
> > + * This way we generate an IPI on the target CPU which
> > * is idle. And the softirq performing nohz idle load balance
> > * will be run before returning from the IPI.
> > */
> > - smp_send_reschedule(ilb_cpu);
> > + smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->wake_csd);
>
> This should be nohz_csd instead of wake_csd, no? I.e.:
>
> smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
>

You figured correctly. Thanks!