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sched/nohz: Remove the 1 Hz tick code

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Now that the 1Hz tick is offloaded to workqueues, we can safely remove
the residual code that used to handle it locally.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1519186649-3242-7-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Frederic Weisbecker 2018-02-21 05:17:28 +01:00 committed by Ingo Molnar
parent d84b31313e
commit dcdedb2415
5 changed files with 1 additions and 50 deletions
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4
include/linux/sched/nohz.h
View file

@ -37,8 +37,4 @@ extern void wake_up_nohz_cpu(int cpu);
static inline void wake_up_nohz_cpu(int cpu) { }
#endif
#ifdef CONFIG_NO_HZ_FULL
extern u64 scheduler_tick_max_deferment(void);
#endif
#endif /* _LINUX_SCHED_NOHZ_H */

29
kernel/sched/core.c
View file

@ -3096,35 +3096,9 @@ void scheduler_tick(void)
rq->idle_balance = idle_cpu(cpu);
trigger_load_balance(rq);
#endif
rq_last_tick_reset(rq);
}
#ifdef CONFIG_NO_HZ_FULL
/**
* scheduler_tick_max_deferment
*
* Keep at least one tick per second when a single
* active task is running because the scheduler doesn't
* yet completely support full dynticks environment.
*
* This makes sure that uptime, CFS vruntime, load
* balancing, etc... continue to move forward, even
* with a very low granularity.
*
* Return: Maximum deferment in nanoseconds.
*/
u64 scheduler_tick_max_deferment(void)
{
struct rq *rq = this_rq();
unsigned long next, now = READ_ONCE(jiffies);
next = rq->last_sched_tick + HZ;
if (time_before_eq(next, now))
return 0;
return jiffies_to_nsecs(next - now);
}
struct tick_work {
int cpu;
@ -6116,9 +6090,6 @@ void __init sched_init(void)
rq->last_load_update_tick = jiffies;
rq->nohz_flags = 0;
#endif
#ifdef CONFIG_NO_HZ_FULL
rq->last_sched_tick = 0;
#endif
#endif /* CONFIG_SMP */
hrtick_rq_init(rq);
atomic_set(&rq->nr_iowait, 0);

1
kernel/sched/idle_task.c
View file

@ -48,7 +48,6 @@ dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
rq_last_tick_reset(rq);
}
/*

11
kernel/sched/sched.h
View file

@ -727,9 +727,7 @@ struct rq {
#endif /* CONFIG_SMP */
unsigned long nohz_flags;
#endif /* CONFIG_NO_HZ_COMMON */
#ifdef CONFIG_NO_HZ_FULL
unsigned long last_sched_tick;
#endif
/* capture load from *all* tasks on this cpu: */
struct load_weight load;
unsigned long nr_load_updates;
@ -1626,13 +1624,6 @@ static inline void sub_nr_running(struct rq *rq, unsigned count)
sched_update_tick_dependency(rq);
}
static inline void rq_last_tick_reset(struct rq *rq)
{
#ifdef CONFIG_NO_HZ_FULL
rq->last_sched_tick = jiffies;
#endif
}
extern void update_rq_clock(struct rq *rq);
extern void activate_task(struct rq *rq, struct task_struct *p, int flags);

6
kernel/time/tick-sched.c
View file

@ -748,12 +748,6 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
delta = KTIME_MAX;
}
#ifdef CONFIG_NO_HZ_FULL
/* Limit the tick delta to the maximum scheduler deferment */
if (!ts->inidle)
delta = min(delta, scheduler_tick_max_deferment());
#endif
/* Calculate the next expiry time */
if (delta < (KTIME_MAX - basemono))
expires = basemono + delta;