From 08bca60a6912ad225254250c0a9c3a05b4152cfa Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 20 May 2011 16:06:29 -0700 Subject: rcu: Remove waitqueue usage for cpu, node, and boost kthreads It is not necessary to use waitqueues for the RCU kthreads because we always know exactly which thread is to be awakened. In addition, wake_up() only issues an actual wakeup when there is a thread waiting on the queue, which was why there was an extra explicit wake_up_process() to get the RCU kthreads started. Eliminating the waitqueues (and wake_up()) in favor of wake_up_process() eliminates the need for the initial wake_up_process() and also shrinks the data structure size a bit. The wakeup logic is placed in a new rcu_wait() macro. Signed-off-by: Peter Zijlstra Signed-off-by: Paul E. McKenney Signed-off-by: Ingo Molnar --- kernel/rcutree_plugin.h | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) (limited to 'kernel/rcutree_plugin.h') diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ed339702481..049f2787a98 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1196,8 +1196,7 @@ static int rcu_boost_kthread(void *arg) for (;;) { rnp->boost_kthread_status = RCU_KTHREAD_WAITING; - wait_event_interruptible(rnp->boost_wq, rnp->boost_tasks || - rnp->exp_tasks); + rcu_wait(rnp->boost_tasks || rnp->exp_tasks); rnp->boost_kthread_status = RCU_KTHREAD_RUNNING; more2boost = rcu_boost(rnp); if (more2boost) @@ -1274,14 +1273,6 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) rnp->boost_time = jiffies + RCU_BOOST_DELAY_JIFFIES; } -/* - * Initialize the RCU-boost waitqueue. - */ -static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp) -{ - init_waitqueue_head(&rnp->boost_wq); -} - /* * Create an RCU-boost kthread for the specified node if one does not * already exist. We only create this kthread for preemptible RCU. @@ -1306,7 +1297,6 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, raw_spin_lock_irqsave(&rnp->lock, flags); rnp->boost_kthread_task = t; raw_spin_unlock_irqrestore(&rnp->lock, flags); - wake_up_process(t); sp.sched_priority = RCU_KTHREAD_PRIO; sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); return 0; @@ -1328,10 +1318,6 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) { } -static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp) -{ -} - static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, struct rcu_node *rnp, int rnp_index) -- cgit v1.2.3