[patch 07/15] sched/hotplug: Convert cpu_[in]active notifiers to state machine

Thomas Gleixner
2016-03-10T12:08:21Z

[-- Attachment #1: sched_hotplug__Convert_cpu__in_active_notifiers_to_state_machine.patch --]
[-- Type: text/plain, Size: 6029 bytes --]

Now that we reduced everything into single notifiers, it's simple to move them
into the hotplug state machine space.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/cpu.h | 12 --------
include/linux/cpuhotplug.h | 1
include/linux/sched.h | 2 +
kernel/cpu.c | 8 ++++-
kernel/sched/core.c | 67 ++++++++++++++-------------------------------
5 files changed, 30 insertions(+), 60 deletions(-)

--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -59,18 +59,6 @@ struct notifier_block;
* CPU notifier priorities.
*/
enum {
- /*
- * SCHED_ACTIVE marks a cpu which is coming up active during
- * CPU_ONLINE and CPU_DOWN_FAILED and must be the first notifier. Is
- * also cpuset according to cpu_active mask right after activating the
- * cpu. During CPU_DOWN_PREPARE, SCHED_INACTIVE reversed the operation.
- *
- * This ordering guarantees consistent cpu_active mask and
- * migration behavior to all cpu notifiers.
- */
- CPU_PRI_SCHED_ACTIVE = INT_MAX,
- CPU_PRI_SCHED_INACTIVE = INT_MIN,
-
/* migration should happen before other stuff but after perf */
CPU_PRI_PERF = 20,
CPU_PRI_MIGRATION = 10,
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -13,6 +13,7 @@ enum cpuhp_state {
CPUHP_AP_ONLINE,
CPUHP_TEARDOWN_CPU,
CPUHP_AP_ONLINE_IDLE,
+ CPUHP_AP_ACTIVE,
CPUHP_AP_SMPBOOT_THREADS,
CPUHP_AP_NOTIFY_ONLINE,
CPUHP_AP_ONLINE_DYN,
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -374,6 +374,8 @@ extern void trap_init(void);
extern void update_process_times(int user);
extern void scheduler_tick(void);
extern int sched_cpu_starting(unsigned int cpu);
+extern int sched_cpu_activate(unsigned int cpu);
+extern int sched_cpu_deactivate(unsigned int cpu);

extern void sched_show_task(struct task_struct *p);

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -904,8 +904,6 @@ void cpuhp_online_idle(enum cpuhp_state

st->state = CPUHP_AP_ONLINE_IDLE;

- /* The cpu is marked online, set it active now */
- set_cpu_active(cpu, true);
/* Unpark the stopper thread and the hotplug thread of this cpu */
stop_machine_unpark(cpu);
kthread_unpark(st->thread);
@@ -1240,6 +1238,12 @@ static struct cpuhp_step cpuhp_ap_states
[CPUHP_AP_ONLINE] = {
.name = "ap:online",
},
+ /* First state is scheduler control. Interrupts are enabled */
+ [CPUHP_AP_ACTIVE] = {
+ .name = "sched:active",
+ .startup = sched_cpu_activate,
+ .teardown = sched_cpu_deactivate,
+ },
/* Handle smpboot threads park/unpark */
[CPUHP_AP_SMPBOOT_THREADS] = {
.name = "smpboot:threads",
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6867,9 +6867,6 @@ static void sched_domains_numa_masks_set
int node = cpu_to_node(cpu);
int i, j;

- if (!sched_smp_initialized)
- return;
-
for (i = 0; i < sched_domains_numa_levels; i++) {
for (j = 0; j < nr_node_ids; j++) {
if (node_distance(j, node) <= sched_domains_numa_distance[i])
@@ -6882,9 +6879,6 @@ static void sched_domains_numa_masks_cle
{
int i, j;

- if (!sched_smp_initialized)
- return;
-
for (i = 0; i < sched_domains_numa_levels; i++) {
for (j = 0; j < nr_node_ids; j++)
cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
@@ -7284,12 +7278,9 @@ static int num_cpus_frozen; /* used to m
* If we come here as part of a suspend/resume, don't touch cpusets because we
* want to restore it back to its original state upon resume anyway.
*/
-static void cpuset_cpu_active(bool frozen)
+static void cpuset_cpu_active(void)
{
- if (!sched_smp_initialized)
- return;
-
- if (frozen) {
+ if (cpuhp_tasks_frozen) {
/*
* num_cpus_frozen tracks how many CPUs are involved in suspend
* resume sequence. As long as this is not the last online
@@ -7310,17 +7301,14 @@ static void cpuset_cpu_active(bool froze
cpuset_update_active_cpus(true);
}

-static int cpuset_cpu_inactive(unsigned int cpu, bool frozen)
+static int cpuset_cpu_inactive(unsigned int cpu)
{
unsigned long flags;
struct dl_bw *dl_b;
bool overflow;
int cpus;

- if (!sched_smp_initialized)
- return 0;
-
- if (!frozen) {
+ if (!cpuhp_tasks_frozen) {
rcu_read_lock_sched();
dl_b = dl_bw_of(cpu);

@@ -7341,42 +7329,33 @@ static int cpuset_cpu_inactive(unsigned
return 0;
}

-static int sched_cpu_active(struct notifier_block *nfb, unsigned long action,
- void *hcpu)
+int sched_cpu_activate(unsigned int cpu)
{
- unsigned int cpu = (unsigned long)hcpu;
+ set_cpu_active(cpu, true);

- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_FAILED:
- case CPU_ONLINE:
- set_cpu_active(cpu, true);
+ if (sched_smp_initialized) {
sched_domains_numa_masks_set(cpu);
- cpuset_cpu_active(action & CPU_TASKS_FROZEN);
- return NOTIFY_OK;
- default:
- return NOTIFY_DONE;
+ cpuset_cpu_active();
}
+ return 0;
}

-static int sched_cpu_inactive(struct notifier_block *nfb,
- unsigned long action, void *hcpu)
+int sched_cpu_deactivate(unsigned int cpu)
{
- unsigned int cpu = (unsigned long)hcpu;
int ret;

- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_PREPARE:
- set_cpu_active(cpu, false);
- ret = cpuset_cpu_inactive(cpu, action & CPU_TASKS_FROZEN);
- if (ret) {
- set_cpu_active(cpu, true);
- return notifier_from_errno(ret);
- }
- sched_domains_numa_masks_clear(cpu);
- return NOTIFY_OK;
- default:
- return NOTIFY_DONE;
+ set_cpu_active(cpu, false);
+
+ if (!sched_smp_initialized)
+ return 0;
+
+ ret = cpuset_cpu_inactive(cpu);
+ if (ret) {
+ set_cpu_active(cpu, true);
+ return ret;
}
+ sched_domains_numa_masks_clear(cpu);
+ return 0;
}

int sched_cpu_starting(unsigned int cpu)
@@ -7430,10 +7409,6 @@ static int __init migration_init(void)
migration_call(&migration_notifier, CPU_ONLINE, cpu);
register_cpu_notifier(&migration_notifier);

- /* Register cpu active notifiers */
- cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
- cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
-
return 0;
}
early_initcall(migration_init);