From a364298359e74a414857bbbf3b725564feb22d09 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@kernel.org>
Date: Wed, 21 Feb 2018 05:17:24 +0100
Subject: nohz: Convert tick_nohz_tick_stopped() to bool
It makes this function more self-explanatory about what it does and how
to use it.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
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/1519186649-3242-3-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'kernel/time/tick-sched.c')
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 29a5733eff83..0aba0412ede5 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -481,7 +481,7 @@ static int __init setup_tick_nohz(char *str)
__setup("nohz=", setup_tick_nohz);
-int tick_nohz_tick_stopped(void)
+bool tick_nohz_tick_stopped(void)
{
return __this_cpu_read(tick_cpu_sched.tick_stopped);
}
--
cgit v1.2.3
From 22ab8bc02a5f6e8ffc418759894f7a6b0b632331 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@kernel.org>
Date: Wed, 21 Feb 2018 05:17:25 +0100
Subject: nohz: Allow to check if remote CPU tick is stopped
This check is racy but provides a good heuristic to determine whether
a CPU may need a remote tick or not.
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/1519186649-3242-4-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/tick.h | 2 ++
kernel/time/tick-sched.c | 7 +++++++
2 files changed, 9 insertions(+)
(limited to 'kernel/time/tick-sched.c')
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 86576d9d2311..7f8c9a127f5a 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -114,6 +114,7 @@ enum tick_dep_bits {
#ifdef CONFIG_NO_HZ_COMMON
extern bool tick_nohz_enabled;
extern bool tick_nohz_tick_stopped(void);
+extern bool tick_nohz_tick_stopped_cpu(int cpu);
extern void tick_nohz_idle_enter(void);
extern void tick_nohz_idle_exit(void);
extern void tick_nohz_irq_exit(void);
@@ -125,6 +126,7 @@ extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
#else /* !CONFIG_NO_HZ_COMMON */
#define tick_nohz_enabled (0)
static inline int tick_nohz_tick_stopped(void) { return 0; }
+static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; }
static inline void tick_nohz_idle_enter(void) { }
static inline void tick_nohz_idle_exit(void) { }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0aba0412ede5..d479b21a848b 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -486,6 +486,13 @@ bool tick_nohz_tick_stopped(void)
return __this_cpu_read(tick_cpu_sched.tick_stopped);
}
+bool tick_nohz_tick_stopped_cpu(int cpu)
+{
+ struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu);
+
+ return ts->tick_stopped;
+}
+
/**
* tick_nohz_update_jiffies - update jiffies when idle was interrupted
*
--
cgit v1.2.3
From dcdedb24159be3487e3dbbe1faa79ae7d00c92ac Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@kernel.org>
Date: Wed, 21 Feb 2018 05:17:28 +0100
Subject: 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>
---
include/linux/sched/nohz.h | 4 ----
kernel/sched/core.c | 29 -----------------------------
kernel/sched/idle_task.c | 1 -
kernel/sched/sched.h | 11 +----------
kernel/time/tick-sched.c | 6 ------
5 files changed, 1 insertion(+), 50 deletions(-)
(limited to 'kernel/time/tick-sched.c')
diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h
index 3d3a97d9399d..094217273ff9 100644
--- 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 5dfef458ab52..8fff4f16c510 100644
--- 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 e1b46e08c8e1..48b8a83f5185 100644
--- 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 c1c7c788da1c..dc6c8b5a24ad 100644
--- 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 d479b21a848b..f2fa2e940fe5 100644
--- 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;
--
cgit v1.2.3