sched/nohz: Remove the 1 Hz tick code

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>

diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h
index 3d3a97d9399d8925a8ea0cf81b2c43bec6bb25e5..094217273ff93350ee54e9b5ef2b512b7cd5f4dc 100644 (file)
--- a/include/linux/sched/nohz.h
+++ b/include/linux/sched/nohz.h
@@ -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 */

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5dfef458ab52933b20465b831b0f7e0221014b9a..8fff4f16c5109c26195d1aeb013d40d18f227047 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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);

diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index e1b46e08c8e1fb2ebb70acb4d17e62e7b676e7e2..48b8a83f51859ce176d09f8612580d5722f953e2 100644 (file)
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -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);
 }
 
 /*

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c1c7c788da1c7f41c5e056807b98deb4445ddc4c..dc6c8b5a24adbd0cee1e8df44bfdedf17b76b48c 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -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);

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index d479b21a848b456382bb850efbd22ede3c9f0603..f2fa2e940fe5fd6ec454143785670dc75dc49111 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -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;