Commit-ID: 3e9f5c70d85060ff0db71826e2048daffec336e7
Gitweb: http://git.kernel.org/tip/3e9f5c70d85060ff0db71826e2048daffec336e7
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 3 Nov 2014 18:15:17 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 6 Jan 2015 11:02:47 -0800
rcu: Don't spawn rcub kthreads on root rcu_node structure
Now that offlining CPUs no longer moves leaf rcu_node structures'
->blkd_tasks lists to the root, there is no way for the root rcu_node
structure's ->blkd_task list to be nonempty, unless the root node is also
the sole leaf node. This commit therefore refrains from creating an rcub
kthread for the root rcu_node structure unless it is also the sole leaf.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index bcc6d91..3e64bb1 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1352,12 +1352,8 @@ static void __init rcu_spawn_boost_kthreads(void)
for_each_possible_cpu(cpu)
per_cpu(rcu_cpu_has_work, cpu) = 0;
BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
- rnp = rcu_get_root(rcu_state_p);
- (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
- if (NUM_RCU_NODES > 1) {
- rcu_for_each_leaf_node(rcu_state_p, rnp)
- (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
- }
+ rcu_for_each_leaf_node(rcu_state_p, rnp)
+ (void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
}
static void rcu_prepare_kthreads(int cpu)
--
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