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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-06-25 08:41:11 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-09-23 07:41:54 -0700
commitb4be093fee0200789df59b6c90e2d099a20f55b3 (patch)
tree5eb8367be67bde57671240bfeb149c4c670ffd1c /kernel
parent4cdfc175c25c89eedc08460b5e6239c2ec67fcb6 (diff)
downloadlinux-b4be093fee0200789df59b6c90e2d099a20f55b3.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcutree.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 6182686de4a6..723e2e723074 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -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)) {