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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: Mike Galbraith <efault@gmx.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Mike Galbraith 2011-08-19 11:39:11 -07:00 committed by Paul E. McKenney
parent ab8f11e5f6
commit 5b61b0baa9
2 changed files with 15 additions and 7 deletions
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2
kernel/rcutree.c
View File

@ -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

20
kernel/rcutree_plugin.h
View File

@ -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);