From c7cd161ecb2188c07ba9560ca82aee756575359f Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Tue, 19 Jun 2018 15:14:17 -0700 Subject: [PATCH] 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) Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 7498a416f63b..8143b8d40a6c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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);