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Commit 3e9f5c70 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 96e92021

kernel/rcu/tree_plugin.h

+2 −6
Original line number Original line Diff line number Diff line
@@ -1352,13 +1352,9 @@ static void __init rcu_spawn_boost_kthreads(void) 
	for_each_possible_cpu(cpu)

	for_each_possible_cpu(cpu)

		per_cpu(rcu_cpu_has_work, cpu) = 0;

		per_cpu(rcu_cpu_has_work, cpu) = 0;

	BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));

	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)

	rcu_for_each_leaf_node(rcu_state_p, rnp)

		(void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);

		(void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);

}

}

}





static void rcu_prepare_kthreads(int cpu)

static void rcu_prepare_kthreads(int cpu)

{

{