Re: [RFC 1/3] rcu: Expedite the rcu quiescent state reporting if help needed

[Joel Fernandes]

On Mon, Jul 01, 2019 at 12:04:13AM -0400, Joel Fernandes (Google) wrote:
> The t->rcu_read_unlock_special union's need_qs bit can be set by the
> scheduler tick (in rcu_flavor_sched_clock_irq) to indicate that help is
> needed from the rcu_read_unlock path. When this help arrives however, we
> can do better to speed up the quiescent state reporting which if
> rcu_read_unlock_special::need_qs is set might be quite urgent. Make use
> of this information in deciding when to do heavy-weight softirq raising
> where possible.

Just fyi, TREE01-06, SRCU-N and SRCU-t passed overnight testing with this series.