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rcu: Unify boost and kthread priorities

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Rename CONFIG_RCU_BOOST_PRIO to CONFIG_RCU_KTHREAD_PRIO and use this
value for both the per-CPU kthreads (rcuc/N) and the rcu boosting
threads (rcub/n).

Also, create the module_parameter rcutree.kthread_prio to be used on
the kernel command line at boot to set a new value (rcutree.kthread_prio=N).

Signed-off-by: Clark Williams <clark.williams@gmail.com>
[ paulmck: Ported to rcu/dev, applied Paul Bolle and Peter Zijlstra feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Clark Williams 2014-09-12 21:21:09 -05:00 • committed by Paul E. McKenney
parent e0775cefb5
commit 21871d7eff
5 changed files with 32 additions and 24 deletions
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20
kernel/rcu/tree_plugin.h
View file

@ -30,12 +30,13 @@
#include <linux/smpboot.h>
#include "../time/tick-internal.h"
#define RCU_KTHREAD_PRIO 1
#ifdef CONFIG_RCU_BOOST
#include "../locking/rtmutex_common.h"
#define RCU_BOOST_PRIO CONFIG_RCU_BOOST_PRIO
/* rcuc/rcub kthread realtime priority */
static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
module_param(kthread_prio, int, 0644);
/*
* Control variables for per-CPU and per-rcu_node kthreads. These
@ -46,11 +47,7 @@ DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
DEFINE_PER_CPU(char, rcu_cpu_has_work);
#else /* #ifdef CONFIG_RCU_BOOST */
#define RCU_BOOST_PRIO RCU_KTHREAD_PRIO
#endif /* #else #ifdef CONFIG_RCU_BOOST */
#endif /* #ifdef CONFIG_RCU_BOOST */
#ifdef CONFIG_RCU_NOCB_CPU
static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
@ -98,6 +95,9 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tBoot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
if (nr_cpu_ids != NR_CPUS)
pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
#ifdef CONFIG_RCU_BOOST
pr_info("\tRCU kthread priority: %d.\n", kthread_prio);
#endif
}
#ifdef CONFIG_TREE_PREEMPT_RCU
@ -1339,7 +1339,7 @@ static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
smp_mb__after_unlock_lock();
rnp->boost_kthread_task = t;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
sp.sched_priority = RCU_BOOST_PRIO;
sp.sched_priority = kthread_prio;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
return 0;
@ -1356,7 +1356,7 @@ static void rcu_cpu_kthread_setup(unsigned int cpu)
{
struct sched_param sp;
sp.sched_priority = RCU_KTHREAD_PRIO;
sp.sched_priority = kthread_prio;
sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
}