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sched/hotplug: Move migration CPU_DYING to sched_cpu_dying() 

Remove the hotplug notifier and make it an explicit state.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.502222097@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2016-03-10 12:54:18 +01:00
parent 7d97669933
commit f2785ddb53
4 changed files with 29 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/cpu.h
View File

@ -59,9 +59,7 @@ struct notifier_block;
* CPU notifier priorities.
*/
enum {
/* migration should happen before other stuff but after perf */
CPU_PRI_PERF = 20,
CPU_PRI_MIGRATION = 10,
/* bring up workqueues before normal notifiers and down after */
CPU_PRI_WORKQUEUE_UP = 5,

6
include/linux/sched.h
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@ -376,6 +376,12 @@ extern int sched_cpu_starting(unsigned int cpu);
extern int sched_cpu_activate(unsigned int cpu);
extern int sched_cpu_deactivate(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
extern int sched_cpu_dying(unsigned int cpu);
#else
# define sched_cpu_dying NULL
#endif
extern void sched_show_task(struct task_struct *p);
#ifdef CONFIG_LOCKUP_DETECTOR

2
kernel/cpu.c
View File

@ -1223,7 +1223,7 @@ static struct cpuhp_step cpuhp_ap_states[] = {
[CPUHP_AP_SCHED_STARTING] = {
.name = "sched:starting",
.startup = sched_cpu_starting,
.teardown = NULL,
.teardown = sched_cpu_dying,
},
/*
* Low level startup/teardown notifiers. Run with interrupts

72
kernel/sched/core.c
View File

@ -5411,51 +5411,6 @@ static void set_rq_offline(struct rq *rq)
}
}
/*
* migration_call - callback that gets triggered when a CPU is added.
* Here we can start up the necessary migration thread for the new CPU.
*/
static int
migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int cpu = (long)hcpu;
unsigned long flags;
struct rq *rq = cpu_rq(cpu);
switch (action & ~CPU_TASKS_FROZEN) {
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
sched_ttwu_pending();
/* Update our root-domain */
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_offline(rq);
}
migrate_tasks(rq);
BUG_ON(rq->nr_running != 1); /* the migration thread */
raw_spin_unlock_irqrestore(&rq->lock, flags);
calc_load_migrate(rq);
break;
#endif
}
update_max_interval();
return NOTIFY_OK;
}
/*
* Register at high priority so that task migration (migrate_all_tasks)
* happens before everything else. This has to be lower priority than
* the notifier in the perf_event subsystem, though.
*/
static struct notifier_block migration_notifier = {
.notifier_call = migration_call,
.priority = CPU_PRI_MIGRATION,
};
static void set_cpu_rq_start_time(unsigned int cpu)
{
struct rq *rq = cpu_rq(cpu);
@ -7158,6 +7113,28 @@ int sched_cpu_starting(unsigned int cpu)
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
int sched_cpu_dying(unsigned int cpu)
{
struct rq *rq = cpu_rq(cpu);
unsigned long flags;
/* Handle pending wakeups and then migrate everything off */
sched_ttwu_pending();
raw_spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_offline(rq);
}
migrate_tasks(rq);
BUG_ON(rq->nr_running != 1);
raw_spin_unlock_irqrestore(&rq->lock, flags);
calc_load_migrate(rq);
update_max_interval();
return 0;
}
#endif
void __init sched_init_smp(void)
{
cpumask_var_t non_isolated_cpus;
@ -7194,12 +7171,7 @@ void __init sched_init_smp(void)
static int __init migration_init(void)
{
void *cpu = (void *)(long)smp_processor_id();
sched_rq_cpu_starting(smp_processor_id());
migration_call(&migration_notifier, CPU_ONLINE, cpu);
register_cpu_notifier(&migration_notifier);
return 0;
}
early_initcall(migration_init);