Commit c7cd161e authored Jun 19, 2018 by Joel Fernandes (Google) Committed by Paul E. McKenney Jul 12, 2018

rcu: Assign higher prio to RCU threads if rcutorture is built-in



The rcutorture RCU priority boosting tests fail even with CONFIG_RCU_BOOST
set because rcutorture's threads run at the same priority as the default
RCU kthreads (RT class with priority of 1).

This patch checks if RCU torture is built into the kernel and if so,
assigns RT priority 1 to the RCU threads, allowing the rcutorture boost
tests to pass.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

parent b7b6f94c

kernel/rcu/tree.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -3923,12 +3923,16 @@ static int __init rcu_spawn_gp_kthread(void)
		struct task_struct *t;

		/* Force priority into range. */
		if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 1)
		if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 2
		&& IS_BUILTIN(CONFIG_RCU_TORTURE_TEST))
		kthread_prio = 2;
		else if (IS_ENABLED(CONFIG_RCU_BOOST) && kthread_prio < 1)
		kthread_prio = 1;
		else if (kthread_prio < 0)
		kthread_prio = 0;
		else if (kthread_prio > 99)
		kthread_prio = 99;

		if (kthread_prio != kthread_prio_in)
		pr_alert("rcu_spawn_gp_kthread(): Limited prio to %d from %d\n",
		kthread_prio, kthread_prio_in);

Admin message