tree 5eb8367be67bde57671240bfeb149c4c670ffd1c
parent 4cdfc175c25c89eedc08460b5e6239c2ec67fcb6
author Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1340638871 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1348411314 -0700

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>