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

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.