[patch 03/15] sched: Make set_cpu_rq_start_time() a built in hotplug state

Thomas Gleixner
2016-03-10T12:06:16Z

[-- Attachment #1: sched--Make-set_cpu_rq_start_time---a-built-in-hotplug-state.patch --]
[-- Type: text/plain, Size: 2580 bytes --]

Start distangling the maze of hotplug notifiers in the scheduler.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/cpuhotplug.h | 1 +
include/linux/sched.h | 1 +
kernel/cpu.c | 6 ++++++
kernel/sched/core.c | 16 +++++++++-------
4 files changed, 17 insertions(+), 7 deletions(-)

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -8,6 +8,7 @@ enum cpuhp_state {
CPUHP_BRINGUP_CPU,
CPUHP_AP_IDLE_DEAD,
CPUHP_AP_OFFLINE,
+ CPUHP_AP_SCHED_STARTING,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,
CPUHP_TEARDOWN_CPU,
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -373,6 +373,7 @@ extern void cpu_init (void);
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 void sched_show_task(struct task_struct *p);

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1217,6 +1217,12 @@ static struct cpuhp_step cpuhp_ap_states
.name = "ap:offline",
.cant_stop = true,
},
+ /* First state is scheduler control. Interrupts are disabled */
+ [CPUHP_AP_SCHED_STARTING] = {
+ .name = "sched:starting",
+ .startup = sched_cpu_starting,
+ .teardown = NULL,
+ },
/*
* Low level startup/teardown notifiers. Run with interrupts
* disabled. Will be removed once the notifiers are converted to
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5711,10 +5711,10 @@ static struct notifier_block migration_n
.priority = CPU_PRI_MIGRATION,
};

-static void set_cpu_rq_start_time(void)
+static void set_cpu_rq_start_time(unsigned int cpu)
{
- int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
+
rq->age_stamp = sched_clock_cpu(cpu);
}

@@ -5724,10 +5724,6 @@ static int sched_cpu_active(struct notif
int cpu = (long)hcpu;

switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_STARTING:
- set_cpu_rq_start_time();
- return NOTIFY_OK;
-
case CPU_DOWN_FAILED:
set_cpu_active(cpu, true);
return NOTIFY_OK;
@@ -5749,6 +5745,12 @@ static int sched_cpu_inactive(struct not
}
}

+int sched_cpu_starting(unsigned int cpu)
+{
+ set_cpu_rq_start_time(cpu);
+ return 0;
+}
+
static int __init migration_init(void)
{
void *cpu = (void *)(long)smp_processor_id();
@@ -7659,7 +7661,7 @@ void __init sched_init(void)
if (cpu_isolated_map == NULL)
zalloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
idle_thread_set_boot_cpu();
- set_cpu_rq_start_time();
+ set_cpu_rq_start_time(smp_processor_id());
#endif
init_sched_fair_class();