From: "Paul E. McKenney" <[email protected]> The rcu_gp_kthread_wake() refuses to do a wakeup unless at least one of the ->gp_flags bits are set, which normally will not be the case when the last quiescent state is reported. This results in up to a 3-jiffy delay given default Kconfig settings. This commit therefore has rcu_report_qs_rsp() set RCU_GP_FLAG_FQS before invoking rcu_gp_kthread_wake() in order to force a more immediate wakeup at grace-period end, thus reducing grace-period latencies.
Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 04bca6b1b9ca..a7615a0b684f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2137,6 +2137,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) __releases(rcu_get_root(rsp)->lock) { WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); + WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS); raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags); rcu_gp_kthread_wake(rsp); } -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
