Commit b4be093f authored Jun 25, 2012 by Paul E. McKenney

rcu: Allow RCU quiescent-state forcing to be preempted



RCU quiescent-state forcing is currently carried out without preemption
points, which can result in excessive latency spikes on large systems
(many hundreds or thousands of CPUs).  This patch therefore inserts
a voluntary preemption point into force_qs_rnp(), which should greatly
reduce the magnitude of these spikes.

Reported-by: Mike Galbraith <mgalbraith@suse.de>
Reported-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

parent 4cdfc175

kernel/rcutree.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1767,6 +1767,7 @@ static void force_qs_rnp(struct rcu_state rsp, int (f)(struct rcu_data *))
		struct rcu_node *rnp;

		rcu_for_each_leaf_node(rsp, rnp) {
		cond_resched();
		mask = 0;
		raw_spin_lock_irqsave(&rnp->lock, flags);
		if (!rcu_gp_in_progress(rsp)) {

Admin message