On Thu, 05 Jul, at 11:52:21AM, Dietmar Eggemann wrote:
>
> Moving the code from _nohz_idle_balance to nohz_idle_balance let it disappear:
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 02be51c9dcc1..070924f07c68 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -9596,16 +9596,6 @@ static bool _nohz_idle_balance(struct rq *this_rq,
> unsigned int flags,
> */
> smp_mb();
>
> - /*
> - * Ensure this_rq's clock and load are up-to-date before we
> - * rebalance since it's possible that they haven't been
> - * updated for multiple schedule periods, i.e. many seconds.
> - */
> - raw_spin_lock_irq(&this_rq->lock);
> - update_rq_clock(this_rq);
> - cpu_load_update_idle(this_rq);
> - raw_spin_unlock_irq(&this_rq->lock);
> -
> for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
> if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
> continue;
> @@ -9701,6 +9691,16 @@ static bool nohz_idle_balance(struct rq *this_rq, enum
> cpu_idle_type idle)
> if (!(flags & NOHZ_KICK_MASK))
> return false;
>
> + /*
> + * Ensure this_rq's clock and load are up-to-date before we
> + * rebalance since it's possible that they haven't been
> + * updated for multiple schedule periods, i.e. many seconds.
> + */
> + raw_spin_lock_irq(&this_rq->lock);
> + update_rq_clock(this_rq);
> + cpu_load_update_idle(this_rq);
> + raw_spin_unlock_irq(&this_rq->lock);
> +
> _nohz_idle_balance(this_rq, flags, idle);
>
> return true;
>
Hmm.. it still looks to me like we should be saving and restoring IRQs
since this can be called from IRQ context, no?
The patch was a forward-port from one of our SLE kernels, and I messed
up the IRQ flag balancing for the v4.18-rc3 code :-(
