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Commit 5b61b0ba authored by Mike Galbraith's avatar Mike Galbraith Committed by Paul E. McKenney
Browse files

rcu: Wire up RCU_BOOST_PRIO for rcutree 



RCU boost threads start life at RCU_BOOST_PRIO, while others remain
at RCU_KTHREAD_PRIO.  While here, change thread names to match other
kthreads, and adjust rcu_yield() to not override the priority set by
the user.  This last change sets the stage for runtime changes to
priority in the -rt tree.

Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent ab8f11e5

kernel/rcutree.c

+0 −2
Original line number Diff line number Diff line
@@ -131,8 +131,6 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); 
static void invoke_rcu_core(void);

static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);



#define RCU_KTHREAD_PRIO 1	/* RT priority for per-CPU kthreads. */



/*

 * Track the rcutorture test sequence number and the update version

 * number within a given test.  The rcutorture_testseq is incremented

kernel/rcutree_plugin.h

+15 −5
Original line number Diff line number Diff line
@@ -27,6 +27,14 @@ 
#include <linux/delay.h>

#include <linux/stop_machine.h>



#define RCU_KTHREAD_PRIO 1



#ifdef CONFIG_RCU_BOOST

#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO

#else

#define RCU_BOOST_PRIO RCU_KTHREAD_PRIO

#endif



/*

 * Check the RCU kernel configuration parameters and print informative

 * messages about anything out of the ordinary.  If you like #ifdef, you
@@ -1364,13 +1372,13 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 
	if (rnp->boost_kthread_task != NULL)

		return 0;

	t = kthread_create(rcu_boost_kthread, (void *)rnp,

			   "rcub%d", rnp_index);

			   "rcub/%d", rnp_index);

	if (IS_ERR(t))

		return PTR_ERR(t);

	raw_spin_lock_irqsave(&rnp->lock, flags);

	rnp->boost_kthread_task = t;

	raw_spin_unlock_irqrestore(&rnp->lock, flags);

	sp.sched_priority = RCU_KTHREAD_PRIO;

	sp.sched_priority = RCU_BOOST_PRIO;

	sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);

	wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */

	return 0;
@@ -1465,6 +1473,7 @@ static void rcu_yield(void (*f)(unsigned long), unsigned long arg) 
{

	struct sched_param sp;

	struct timer_list yield_timer;

	int prio = current->rt_priority;



	setup_timer_on_stack(&yield_timer, f, arg);

	mod_timer(&yield_timer, jiffies + 2);
@@ -1472,7 +1481,8 @@ static void rcu_yield(void (*f)(unsigned long), unsigned long arg) 
	sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp);

	set_user_nice(current, 19);

	schedule();

	sp.sched_priority = RCU_KTHREAD_PRIO;

	set_user_nice(current, 0);

	sp.sched_priority = prio;

	sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);

	del_timer(&yield_timer);

}
@@ -1591,7 +1601,7 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu) 
	t = kthread_create_on_node(rcu_cpu_kthread,

				   (void *)(long)cpu,

				   cpu_to_node(cpu),

				   "rcuc%d", cpu);

				   "rcuc/%d", cpu);

	if (IS_ERR(t))

		return PTR_ERR(t);

	if (cpu_online(cpu))
@@ -1700,7 +1710,7 @@ static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp, 
		return 0;

	if (rnp->node_kthread_task == NULL) {

		t = kthread_create(rcu_node_kthread, (void *)rnp,

				   "rcun%d", rnp_index);

				   "rcun/%d", rnp_index);

		if (IS_ERR(t))

			return PTR_ERR(t);

		raw_spin_lock_irqsave(&rnp->lock, flags);