Date:   Tue, 19 Dec 2017 04:23:54 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Luiz Capitulino <lcapitulino@...hat.com>,
        Christoph Lameter <cl@...ux.com>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Wanpeng Li <kernellwp@...il.com>,
        Mike Galbraith <efault@....de>, Rik van Riel <riel@...hat.com>
Subject: [PATCH 1/5] sched: Move tick code to a separate file

Let's debloat some more core.c
Also we are going to expand the tick code even further to introduce
scheduler tick offloading.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <kernellwp@...il.com>
Cc: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/Makefile |   2 +-
 kernel/sched/core.c   | 182 --------------------------------------------------
 kernel/sched/sched.h  |   7 +-
 kernel/sched/tick.c   | 177 ++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 184 insertions(+), 184 deletions(-)
 create mode 100644 kernel/sched/tick.c

diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index e2f9d4f..dd0b01e 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -16,7 +16,7 @@ ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 CFLAGS_core.o := $(PROFILING) -fno-omit-frame-pointer
 endif
 
-obj-y += core.o loadavg.o clock.o cputime.o
+obj-y += core.o loadavg.o clock.o cputime.o tick.o
 obj-y += idle_task.o fair.o rt.o deadline.o
 obj-y += wait.o wait_bit.o swait.o completion.o idle.o
 obj-$(CONFIG_SMP) += cpupri.o cpudeadline.o topology.o stop_task.o
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 644fa2e..06af4fa 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -233,129 +233,6 @@ void update_rq_clock(struct rq *rq)
 	update_rq_clock_task(rq, delta);
 }
 
-
-#ifdef CONFIG_SCHED_HRTICK
-/*
- * Use HR-timers to deliver accurate preemption points.
- */
-
-static void hrtick_clear(struct rq *rq)
-{
-	if (hrtimer_active(&rq->hrtick_timer))
-		hrtimer_cancel(&rq->hrtick_timer);
-}
-
-/*
- * High-resolution timer tick.
- * Runs from hardirq context with interrupts disabled.
- */
-static enum hrtimer_restart hrtick(struct hrtimer *timer)
-{
-	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
-	struct rq_flags rf;
-
-	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
-
-	rq_lock(rq, &rf);
-	update_rq_clock(rq);
-	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
-	rq_unlock(rq, &rf);
-
-	return HRTIMER_NORESTART;
-}
-
-#ifdef CONFIG_SMP
-
-static void __hrtick_restart(struct rq *rq)
-{
-	struct hrtimer *timer = &rq->hrtick_timer;
-
-	hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
-}
-
-/*
- * called from hardirq (IPI) context
- */
-static void __hrtick_start(void *arg)
-{
-	struct rq *rq = arg;
-	struct rq_flags rf;
-
-	rq_lock(rq, &rf);
-	__hrtick_restart(rq);
-	rq->hrtick_csd_pending = 0;
-	rq_unlock(rq, &rf);
-}
-
-/*
- * Called to set the hrtick timer state.
- *
- * called with rq->lock held and irqs disabled
- */
-void hrtick_start(struct rq *rq, u64 delay)
-{
-	struct hrtimer *timer = &rq->hrtick_timer;
-	ktime_t time;
-	s64 delta;
-
-	/*
-	 * Don't schedule slices shorter than 10000ns, that just
-	 * doesn't make sense and can cause timer DoS.
-	 */
-	delta = max_t(s64, delay, 10000LL);
-	time = ktime_add_ns(timer->base->get_time(), delta);
-
-	hrtimer_set_expires(timer, time);
-
-	if (rq == this_rq()) {
-		__hrtick_restart(rq);
-	} else if (!rq->hrtick_csd_pending) {
-		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
-		rq->hrtick_csd_pending = 1;
-	}
-}
-
-#else
-/*
- * Called to set the hrtick timer state.
- *
- * called with rq->lock held and irqs disabled
- */
-void hrtick_start(struct rq *rq, u64 delay)
-{
-	/*
-	 * Don't schedule slices shorter than 10000ns, that just
-	 * doesn't make sense. Rely on vruntime for fairness.
-	 */
-	delay = max_t(u64, delay, 10000LL);
-	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
-		      HRTIMER_MODE_REL_PINNED);
-}
-#endif /* CONFIG_SMP */
-
-static void init_rq_hrtick(struct rq *rq)
-{
-#ifdef CONFIG_SMP
-	rq->hrtick_csd_pending = 0;
-
-	rq->hrtick_csd.flags = 0;
-	rq->hrtick_csd.func = __hrtick_start;
-	rq->hrtick_csd.info = rq;
-#endif
-
-	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-	rq->hrtick_timer.function = hrtick;
-}
-#else	/* CONFIG_SCHED_HRTICK */
-static inline void hrtick_clear(struct rq *rq)
-{
-}
-
-static inline void init_rq_hrtick(struct rq *rq)
-{
-}
-#endif	/* CONFIG_SCHED_HRTICK */
-
 /*
  * cmpxchg based fetch_or, macro so it works for different integer types
  */
@@ -3005,65 +2882,6 @@ unsigned long long task_sched_runtime(struct task_struct *p)
 	return ns;
 }
 
-/*
- * This function gets called by the timer code, with HZ frequency.
- * We call it with interrupts disabled.
- */
-void scheduler_tick(void)
-{
-	int cpu = smp_processor_id();
-	struct rq *rq = cpu_rq(cpu);
-	struct task_struct *curr = rq->curr;
-	struct rq_flags rf;
-
-	sched_clock_tick();
-
-	rq_lock(rq, &rf);
-
-	update_rq_clock(rq);
-	curr->sched_class->task_tick(rq, curr, 0);
-	cpu_load_update_active(rq);
-	calc_global_load_tick(rq);
-
-	rq_unlock(rq, &rf);
-
-	perf_event_task_tick();
-
-#ifdef CONFIG_SMP
-	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);
-}
-#endif
-
 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
 				defined(CONFIG_PREEMPT_TRACER))
 /*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b19552a2..43f065e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1676,7 +1676,9 @@ static inline int hrtick_enabled(struct rq *rq)
 	return hrtimer_is_hres_active(&rq->hrtick_timer);
 }
 
-void hrtick_start(struct rq *rq, u64 delay);
+extern void hrtick_start(struct rq *rq, u64 delay);
+extern void hrtick_clear(struct rq *rq);
+extern void init_rq_hrtick(struct rq *rq);
 
 #else
 
@@ -1685,6 +1687,9 @@ static inline int hrtick_enabled(struct rq *rq)
 	return 0;
 }
 
+static inline void hrtick_clear(struct rq *rq) { }
+static inline void init_rq_hrtick(struct rq *rq) { }
+
 #endif /* CONFIG_SCHED_HRTICK */
 
 #ifdef CONFIG_SMP
diff --git a/kernel/sched/tick.c b/kernel/sched/tick.c
new file mode 100644
index 0000000..bcc6d7d
--- /dev/null
+++ b/kernel/sched/tick.c
@@ -0,0 +1,177 @@
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/perf_event.h>
+#include "sched.h"
+
+/*
+ * This function gets called by the timer code, with HZ frequency.
+ * We call it with interrupts disabled.
+ */
+void scheduler_tick(void)
+{
+	int cpu = smp_processor_id();
+	struct rq *rq = cpu_rq(cpu);
+	struct task_struct *curr = rq->curr;
+	struct rq_flags rf;
+
+	sched_clock_tick();
+
+	rq_lock(rq, &rf);
+
+	update_rq_clock(rq);
+	curr->sched_class->task_tick(rq, curr, 0);
+	cpu_load_update_active(rq);
+	calc_global_load_tick(rq);
+
+	rq_unlock(rq, &rf);
+
+	perf_event_task_tick();
+
+#ifdef CONFIG_SMP
+	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);
+}
+#endif
+
+#ifdef CONFIG_SCHED_HRTICK
+/*
+ * Use HR-timers to deliver accurate preemption points.
+ */
+
+void hrtick_clear(struct rq *rq)
+{
+	if (hrtimer_active(&rq->hrtick_timer))
+		hrtimer_cancel(&rq->hrtick_timer);
+}
+
+/*
+ * High-resolution timer tick.
+ * Runs from hardirq context with interrupts disabled.
+ */
+static enum hrtimer_restart hrtick(struct hrtimer *timer)
+{
+	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
+	struct rq_flags rf;
+
+	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
+
+	rq_lock(rq, &rf);
+	update_rq_clock(rq);
+	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
+	rq_unlock(rq, &rf);
+
+	return HRTIMER_NORESTART;
+}
+
+#ifdef CONFIG_SMP
+
+static void __hrtick_restart(struct rq *rq)
+{
+	struct hrtimer *timer = &rq->hrtick_timer;
+
+	hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
+}
+
+/*
+ * called from hardirq (IPI) context
+ */
+static void __hrtick_start(void *arg)
+{
+	struct rq *rq = arg;
+	struct rq_flags rf;
+
+	rq_lock(rq, &rf);
+	__hrtick_restart(rq);
+	rq->hrtick_csd_pending = 0;
+	rq_unlock(rq, &rf);
+}
+
+/*
+ * Called to set the hrtick timer state.
+ *
+ * called with rq->lock held and irqs disabled
+ */
+void hrtick_start(struct rq *rq, u64 delay)
+{
+	struct hrtimer *timer = &rq->hrtick_timer;
+	ktime_t time;
+	s64 delta;
+
+	/*
+	 * Don't schedule slices shorter than 10000ns, that just
+	 * doesn't make sense and can cause timer DoS.
+	 */
+	delta = max_t(s64, delay, 10000LL);
+	time = ktime_add_ns(timer->base->get_time(), delta);
+
+	hrtimer_set_expires(timer, time);
+
+	if (rq == this_rq()) {
+		__hrtick_restart(rq);
+	} else if (!rq->hrtick_csd_pending) {
+		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
+		rq->hrtick_csd_pending = 1;
+	}
+}
+
+#else
+/*
+ * Called to set the hrtick timer state.
+ *
+ * called with rq->lock held and irqs disabled
+ */
+void hrtick_start(struct rq *rq, u64 delay)
+{
+	/*
+	 * Don't schedule slices shorter than 10000ns, that just
+	 * doesn't make sense. Rely on vruntime for fairness.
+	 */
+	delay = max_t(u64, delay, 10000LL);
+	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
+		      HRTIMER_MODE_REL_PINNED);
+}
+#endif /* CONFIG_SMP */
+
+void init_rq_hrtick(struct rq *rq)
+{
+#ifdef CONFIG_SMP
+	rq->hrtick_csd_pending = 0;
+
+	rq->hrtick_csd.flags = 0;
+	rq->hrtick_csd.func = __hrtick_start;
+	rq->hrtick_csd.info = rq;
+#endif
+
+	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	rq->hrtick_timer.function = hrtick;
+}
+#endif	/* CONFIG_SCHED_HRTICK */
-- 
2.7.4

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