| From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 10/23] rcu: Allow RCU quiescent-state forcing to be preempted | Date | Thu, 30 Aug 2012 11:18:25 -0700 |
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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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> --- kernel/rcutree.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 79c2c28..cce73ff 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1784,6 +1784,7 @@ 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)) { -- 1.7.8
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