[patch 11/15] sched/migration: Move CPU_ONLINE into scheduler state

Thomas Gleixner
2016-03-10T12:07:42Z

[-- Attachment #1: sched-migration--Move-CPU_ONLINE-into-scheduler-state.patch --]
[-- Type: text/plain, Size: 1788 bytes --]

The alleged requirement that the migration notifier has a lower priority than
perf is completely undocumented and there is no indication at all that this is
true. perf does not even handle the CPU_ONLINE notification and perf really
has nothing to do with migration.

Move the CPU_ONLINE code into the sched_activate_cpu() state callback.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/sched/core.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5662,17 +5662,6 @@ migration_call(struct notifier_block *nf

switch (action & ~CPU_TASKS_FROZEN) {

- case CPU_ONLINE:
- /* 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_online(rq);
- }
- raw_spin_unlock_irqrestore(&rq->lock, flags);
- break;
-
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
sched_ttwu_pending();
@@ -7323,12 +7312,34 @@ static int cpuset_cpu_inactive(unsigned

int sched_cpu_activate(unsigned int cpu)
{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
set_cpu_active(cpu, true);

if (sched_smp_initialized) {
sched_domains_numa_masks_set(cpu);
cpuset_cpu_active();
}
+
+ /*
+ * Put the rq online, if not already. This happens:
+ *
+ * 1) In the early boot process, because we build the real domains
+ * after all cpus have been brought up.
+ *
+ * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
+ * domains.
+ */
+ raw_spin_lock_irqsave(&rq->lock, flags);
+ if (rq->rd) {
+ BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
+ set_rq_online(rq);
+ }
+ raw_spin_unlock_irqrestore(&rq->lock, flags);
+
+ update_max_interval();
+
return 0;
}