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87fefa381e
due to the fact that we no longer keep the 'current' within the tree, dequeue/enqueue_entity() is useless for the 'current' in task_new_fair(). We are about to reschedule and sched_class->put_prev_task() will put the 'current' back into the tree, based on its new key. text data bss dec hex filename 24388 2734 20 27142 6a06 sched.o.before 24341 2734 20 27095 69d7 sched.o.after Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
1040 lines
25 KiB
C
1040 lines
25 KiB
C
/*
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* Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
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*
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* Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* Interactivity improvements by Mike Galbraith
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* (C) 2007 Mike Galbraith <efault@gmx.de>
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*
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* Various enhancements by Dmitry Adamushko.
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* (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
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*
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* Group scheduling enhancements by Srivatsa Vaddagiri
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* Copyright IBM Corporation, 2007
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* Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
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*
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* Scaled math optimizations by Thomas Gleixner
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* Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
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*
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* Adaptive scheduling granularity, math enhancements by Peter Zijlstra
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*/
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/*
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* Targeted preemption latency for CPU-bound tasks:
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* (default: 20ms, units: nanoseconds)
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*
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* NOTE: this latency value is not the same as the concept of
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* 'timeslice length' - timeslices in CFS are of variable length.
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* (to see the precise effective timeslice length of your workload,
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* run vmstat and monitor the context-switches field)
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*
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* On SMP systems the value of this is multiplied by the log2 of the
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* number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way
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* systems, 4x on 8-way systems, 5x on 16-way systems, etc.)
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* Targeted preemption latency for CPU-bound tasks:
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*/
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const_debug unsigned int sysctl_sched_latency = 20000000ULL;
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/*
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* After fork, child runs first. (default) If set to 0 then
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* parent will (try to) run first.
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*/
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const_debug unsigned int sysctl_sched_child_runs_first = 1;
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/*
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* Minimal preemption granularity for CPU-bound tasks:
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* (default: 2 msec, units: nanoseconds)
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*/
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unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL;
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/*
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* sys_sched_yield() compat mode
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*
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* This option switches the agressive yield implementation of the
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* old scheduler back on.
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*/
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unsigned int __read_mostly sysctl_sched_compat_yield;
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/*
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* SCHED_BATCH wake-up granularity.
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* (default: 25 msec, units: nanoseconds)
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*
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* This option delays the preemption effects of decoupled workloads
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* and reduces their over-scheduling. Synchronous workloads will still
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* have immediate wakeup/sleep latencies.
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*/
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const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 25000000UL;
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/*
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* SCHED_OTHER wake-up granularity.
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* (default: 1 msec, units: nanoseconds)
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*
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* This option delays the preemption effects of decoupled workloads
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* and reduces their over-scheduling. Synchronous workloads will still
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* have immediate wakeup/sleep latencies.
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*/
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const_debug unsigned int sysctl_sched_wakeup_granularity = 2000000UL;
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unsigned int sysctl_sched_runtime_limit __read_mostly;
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extern struct sched_class fair_sched_class;
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/**************************************************************
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* CFS operations on generic schedulable entities:
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*/
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#ifdef CONFIG_FAIR_GROUP_SCHED
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/* cpu runqueue to which this cfs_rq is attached */
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->rq;
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}
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/* An entity is a task if it doesn't "own" a runqueue */
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#define entity_is_task(se) (!se->my_q)
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#else /* CONFIG_FAIR_GROUP_SCHED */
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
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{
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return container_of(cfs_rq, struct rq, cfs);
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}
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#define entity_is_task(se) 1
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#endif /* CONFIG_FAIR_GROUP_SCHED */
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static inline struct task_struct *task_of(struct sched_entity *se)
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{
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return container_of(se, struct task_struct, se);
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}
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/**************************************************************
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* Scheduling class tree data structure manipulation methods:
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*/
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static inline u64
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max_vruntime(u64 min_vruntime, u64 vruntime)
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{
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if ((vruntime > min_vruntime) ||
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(min_vruntime > (1ULL << 61) && vruntime < (1ULL << 50)))
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min_vruntime = vruntime;
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return min_vruntime;
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}
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static inline void
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set_leftmost(struct cfs_rq *cfs_rq, struct rb_node *leftmost)
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{
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struct sched_entity *se;
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cfs_rq->rb_leftmost = leftmost;
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if (leftmost)
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se = rb_entry(leftmost, struct sched_entity, run_node);
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}
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static inline s64
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entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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return se->vruntime - cfs_rq->min_vruntime;
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}
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/*
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* Enqueue an entity into the rb-tree:
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*/
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static void
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__enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
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struct rb_node *parent = NULL;
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struct sched_entity *entry;
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s64 key = entity_key(cfs_rq, se);
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int leftmost = 1;
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/*
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* Find the right place in the rbtree:
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*/
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while (*link) {
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parent = *link;
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entry = rb_entry(parent, struct sched_entity, run_node);
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/*
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* We dont care about collisions. Nodes with
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* the same key stay together.
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*/
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if (key < entity_key(cfs_rq, entry)) {
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link = &parent->rb_left;
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} else {
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link = &parent->rb_right;
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leftmost = 0;
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}
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}
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/*
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* Maintain a cache of leftmost tree entries (it is frequently
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* used):
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*/
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if (leftmost)
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set_leftmost(cfs_rq, &se->run_node);
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rb_link_node(&se->run_node, parent, link);
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rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
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}
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static void
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__dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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if (cfs_rq->rb_leftmost == &se->run_node)
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set_leftmost(cfs_rq, rb_next(&se->run_node));
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rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
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}
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static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->rb_leftmost;
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}
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static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
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{
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return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node);
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}
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static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
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{
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struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
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struct sched_entity *se = NULL;
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struct rb_node *parent;
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while (*link) {
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parent = *link;
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se = rb_entry(parent, struct sched_entity, run_node);
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link = &parent->rb_right;
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}
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return se;
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}
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/**************************************************************
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* Scheduling class statistics methods:
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*/
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static u64 __sched_period(unsigned long nr_running)
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{
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u64 period = sysctl_sched_latency;
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unsigned long nr_latency =
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sysctl_sched_latency / sysctl_sched_min_granularity;
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if (unlikely(nr_running > nr_latency)) {
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period *= nr_running;
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do_div(period, nr_latency);
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}
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return period;
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}
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static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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u64 period = __sched_period(cfs_rq->nr_running);
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period *= se->load.weight;
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do_div(period, cfs_rq->load.weight);
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return period;
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}
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/*
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* Update the current task's runtime statistics. Skip current tasks that
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* are not in our scheduling class.
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*/
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static inline void
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__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
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unsigned long delta_exec)
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{
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unsigned long delta_exec_weighted;
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u64 next_vruntime, min_vruntime;
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schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max));
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curr->sum_exec_runtime += delta_exec;
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schedstat_add(cfs_rq, exec_clock, delta_exec);
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delta_exec_weighted = delta_exec;
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if (unlikely(curr->load.weight != NICE_0_LOAD)) {
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delta_exec_weighted = calc_delta_fair(delta_exec_weighted,
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&curr->load);
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}
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curr->vruntime += delta_exec_weighted;
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/*
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* maintain cfs_rq->min_vruntime to be a monotonic increasing
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* value tracking the leftmost vruntime in the tree.
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*/
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if (first_fair(cfs_rq)) {
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next_vruntime = __pick_next_entity(cfs_rq)->vruntime;
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/* min_vruntime() := !max_vruntime() */
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min_vruntime = max_vruntime(curr->vruntime, next_vruntime);
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if (min_vruntime == next_vruntime)
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min_vruntime = curr->vruntime;
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else
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min_vruntime = next_vruntime;
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} else
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min_vruntime = curr->vruntime;
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cfs_rq->min_vruntime =
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max_vruntime(cfs_rq->min_vruntime, min_vruntime);
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}
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static void update_curr(struct cfs_rq *cfs_rq)
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{
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struct sched_entity *curr = cfs_rq->curr;
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u64 now = rq_of(cfs_rq)->clock;
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unsigned long delta_exec;
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if (unlikely(!curr))
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return;
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/*
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* Get the amount of time the current task was running
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* since the last time we changed load (this cannot
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* overflow on 32 bits):
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*/
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delta_exec = (unsigned long)(now - curr->exec_start);
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__update_curr(cfs_rq, curr, delta_exec);
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curr->exec_start = now;
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}
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static inline void
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update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
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}
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static inline unsigned long
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calc_weighted(unsigned long delta, struct sched_entity *se)
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{
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unsigned long weight = se->load.weight;
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if (unlikely(weight != NICE_0_LOAD))
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return (u64)delta * se->load.weight >> NICE_0_SHIFT;
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else
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return delta;
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}
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/*
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* Task is being enqueued - update stats:
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*/
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static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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/*
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* Are we enqueueing a waiting task? (for current tasks
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* a dequeue/enqueue event is a NOP)
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*/
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if (se != cfs_rq->curr)
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update_stats_wait_start(cfs_rq, se);
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}
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static void
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update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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schedstat_set(se->wait_max, max(se->wait_max,
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rq_of(cfs_rq)->clock - se->wait_start));
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schedstat_set(se->wait_start, 0);
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}
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static inline void
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update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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update_curr(cfs_rq);
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/*
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* Mark the end of the wait period if dequeueing a
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* waiting task:
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*/
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if (se != cfs_rq->curr)
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update_stats_wait_end(cfs_rq, se);
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}
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/*
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* We are picking a new current task - update its stats:
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*/
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static inline void
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update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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/*
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* We are starting a new run period:
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*/
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se->exec_start = rq_of(cfs_rq)->clock;
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}
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/*
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* We are descheduling a task - update its stats:
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*/
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static inline void
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update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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se->exec_start = 0;
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}
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/**************************************************
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* Scheduling class queueing methods:
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*/
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static void
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account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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update_load_add(&cfs_rq->load, se->load.weight);
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cfs_rq->nr_running++;
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se->on_rq = 1;
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}
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static void
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account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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update_load_sub(&cfs_rq->load, se->load.weight);
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cfs_rq->nr_running--;
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se->on_rq = 0;
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}
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static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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#ifdef CONFIG_SCHEDSTATS
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if (se->sleep_start) {
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u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
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if ((s64)delta < 0)
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delta = 0;
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if (unlikely(delta > se->sleep_max))
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se->sleep_max = delta;
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se->sleep_start = 0;
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se->sum_sleep_runtime += delta;
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}
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if (se->block_start) {
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u64 delta = rq_of(cfs_rq)->clock - se->block_start;
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if ((s64)delta < 0)
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delta = 0;
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if (unlikely(delta > se->block_max))
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se->block_max = delta;
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se->block_start = 0;
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se->sum_sleep_runtime += delta;
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/*
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* Blocking time is in units of nanosecs, so shift by 20 to
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* get a milliseconds-range estimation of the amount of
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* time that the task spent sleeping:
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*/
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if (unlikely(prof_on == SLEEP_PROFILING)) {
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struct task_struct *tsk = task_of(se);
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profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
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delta >> 20);
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}
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}
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#endif
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}
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static void
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place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
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{
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u64 min_runtime, latency;
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min_runtime = cfs_rq->min_vruntime;
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if (sched_feat(USE_TREE_AVG)) {
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struct sched_entity *last = __pick_last_entity(cfs_rq);
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if (last) {
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min_runtime = __pick_next_entity(cfs_rq)->vruntime;
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min_runtime += last->vruntime;
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min_runtime >>= 1;
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}
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} else if (sched_feat(APPROX_AVG))
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min_runtime += sysctl_sched_latency/2;
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if (initial && sched_feat(START_DEBIT))
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min_runtime += sched_slice(cfs_rq, se);
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if (!initial && sched_feat(NEW_FAIR_SLEEPERS)) {
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latency = sysctl_sched_latency;
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if (min_runtime > latency)
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min_runtime -= latency;
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else
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min_runtime = 0;
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}
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se->vruntime = max(se->vruntime, min_runtime);
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}
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static void
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enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
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{
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/*
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* Update the fair clock.
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*/
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update_curr(cfs_rq);
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if (wakeup) {
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place_entity(cfs_rq, se, 0);
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enqueue_sleeper(cfs_rq, se);
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}
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update_stats_enqueue(cfs_rq, se);
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if (se != cfs_rq->curr)
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__enqueue_entity(cfs_rq, se);
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account_entity_enqueue(cfs_rq, se);
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}
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static void
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dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
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{
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update_stats_dequeue(cfs_rq, se);
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#ifdef CONFIG_SCHEDSTATS
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if (sleep) {
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if (entity_is_task(se)) {
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struct task_struct *tsk = task_of(se);
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if (tsk->state & TASK_INTERRUPTIBLE)
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se->sleep_start = rq_of(cfs_rq)->clock;
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if (tsk->state & TASK_UNINTERRUPTIBLE)
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se->block_start = rq_of(cfs_rq)->clock;
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}
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}
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#endif
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if (se != cfs_rq->curr)
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__dequeue_entity(cfs_rq, se);
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account_entity_dequeue(cfs_rq, se);
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}
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|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void
|
|
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
|
|
{
|
|
unsigned long ideal_runtime, delta_exec;
|
|
|
|
ideal_runtime = sched_slice(cfs_rq, curr);
|
|
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
|
|
if (delta_exec > ideal_runtime)
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
}
|
|
|
|
static inline void
|
|
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* Any task has to be enqueued before it get to execute on
|
|
* a CPU. So account for the time it spent waiting on the
|
|
* runqueue.
|
|
*/
|
|
update_stats_wait_end(cfs_rq, se);
|
|
update_stats_curr_start(cfs_rq, se);
|
|
cfs_rq->curr = se;
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
/*
|
|
* Track our maximum slice length, if the CPU's load is at
|
|
* least twice that of our own weight (i.e. dont track it
|
|
* when there are only lesser-weight tasks around):
|
|
*/
|
|
if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
|
|
se->slice_max = max(se->slice_max,
|
|
se->sum_exec_runtime - se->prev_sum_exec_runtime);
|
|
}
|
|
#endif
|
|
se->prev_sum_exec_runtime = se->sum_exec_runtime;
|
|
}
|
|
|
|
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *se = __pick_next_entity(cfs_rq);
|
|
|
|
/* 'current' is not kept within the tree. */
|
|
if (se)
|
|
__dequeue_entity(cfs_rq, se);
|
|
|
|
set_next_entity(cfs_rq, se);
|
|
|
|
return se;
|
|
}
|
|
|
|
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
|
|
{
|
|
/*
|
|
* If still on the runqueue then deactivate_task()
|
|
* was not called and update_curr() has to be done:
|
|
*/
|
|
if (prev->on_rq)
|
|
update_curr(cfs_rq);
|
|
|
|
update_stats_curr_end(cfs_rq, prev);
|
|
|
|
if (prev->on_rq) {
|
|
update_stats_wait_start(cfs_rq, prev);
|
|
/* Put 'current' back into the tree. */
|
|
__enqueue_entity(cfs_rq, prev);
|
|
}
|
|
cfs_rq->curr = NULL;
|
|
}
|
|
|
|
static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
if (cfs_rq->nr_running > 1)
|
|
check_preempt_tick(cfs_rq, curr);
|
|
}
|
|
|
|
/**************************************************
|
|
* CFS operations on tasks:
|
|
*/
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
|
|
/* Walk up scheduling entities hierarchy */
|
|
#define for_each_sched_entity(se) \
|
|
for (; se; se = se->parent)
|
|
|
|
static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
|
|
{
|
|
return p->se.cfs_rq;
|
|
}
|
|
|
|
/* runqueue on which this entity is (to be) queued */
|
|
static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
|
|
{
|
|
return se->cfs_rq;
|
|
}
|
|
|
|
/* runqueue "owned" by this group */
|
|
static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
|
|
{
|
|
return grp->my_q;
|
|
}
|
|
|
|
/* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
|
|
* another cpu ('this_cpu')
|
|
*/
|
|
static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
|
|
{
|
|
return cfs_rq->tg->cfs_rq[this_cpu];
|
|
}
|
|
|
|
/* Iterate thr' all leaf cfs_rq's on a runqueue */
|
|
#define for_each_leaf_cfs_rq(rq, cfs_rq) \
|
|
list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
|
|
|
|
/* Do the two (enqueued) tasks belong to the same group ? */
|
|
static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
|
|
{
|
|
if (curr->se.cfs_rq == p->se.cfs_rq)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#else /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
#define for_each_sched_entity(se) \
|
|
for (; se; se = NULL)
|
|
|
|
static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
|
|
{
|
|
return &task_rq(p)->cfs;
|
|
}
|
|
|
|
static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
|
|
{
|
|
struct task_struct *p = task_of(se);
|
|
struct rq *rq = task_rq(p);
|
|
|
|
return &rq->cfs;
|
|
}
|
|
|
|
/* runqueue "owned" by this group */
|
|
static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
|
|
{
|
|
return &cpu_rq(this_cpu)->cfs;
|
|
}
|
|
|
|
#define for_each_leaf_cfs_rq(rq, cfs_rq) \
|
|
for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
|
|
|
|
static inline int is_same_group(struct task_struct *curr, struct task_struct *p)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
/*
|
|
* The enqueue_task method is called before nr_running is
|
|
* increased. Here we update the fair scheduling stats and
|
|
* then put the task into the rbtree:
|
|
*/
|
|
static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
if (se->on_rq)
|
|
break;
|
|
cfs_rq = cfs_rq_of(se);
|
|
enqueue_entity(cfs_rq, se, wakeup);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The dequeue_task method is called before nr_running is
|
|
* decreased. We remove the task from the rbtree and
|
|
* update the fair scheduling stats:
|
|
*/
|
|
static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
dequeue_entity(cfs_rq, se, sleep);
|
|
/* Don't dequeue parent if it has other entities besides us */
|
|
if (cfs_rq->load.weight)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* sched_yield() support is very simple - we dequeue and enqueue.
|
|
*
|
|
* If compat_yield is turned on then we requeue to the end of the tree.
|
|
*/
|
|
static void yield_task_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
|
|
struct sched_entity *rightmost, *se = &p->se;
|
|
struct rb_node *parent;
|
|
|
|
/*
|
|
* Are we the only task in the tree?
|
|
*/
|
|
if (unlikely(cfs_rq->nr_running == 1))
|
|
return;
|
|
|
|
if (likely(!sysctl_sched_compat_yield)) {
|
|
__update_rq_clock(rq);
|
|
/*
|
|
* Dequeue and enqueue the task to update its
|
|
* position within the tree:
|
|
*/
|
|
dequeue_entity(cfs_rq, &p->se, 0);
|
|
enqueue_entity(cfs_rq, &p->se, 0);
|
|
|
|
return;
|
|
}
|
|
/*
|
|
* Find the rightmost entry in the rbtree:
|
|
*/
|
|
do {
|
|
parent = *link;
|
|
link = &parent->rb_right;
|
|
} while (*link);
|
|
|
|
rightmost = rb_entry(parent, struct sched_entity, run_node);
|
|
/*
|
|
* Already in the rightmost position?
|
|
*/
|
|
if (unlikely(rightmost == se))
|
|
return;
|
|
|
|
/*
|
|
* Minimally necessary key value to be last in the tree:
|
|
*/
|
|
se->vruntime = rightmost->vruntime + 1;
|
|
|
|
if (cfs_rq->rb_leftmost == &se->run_node)
|
|
cfs_rq->rb_leftmost = rb_next(&se->run_node);
|
|
/*
|
|
* Relink the task to the rightmost position:
|
|
*/
|
|
rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
|
|
rb_link_node(&se->run_node, parent, link);
|
|
rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
|
|
if (unlikely(rt_prio(p->prio))) {
|
|
update_rq_clock(rq);
|
|
update_curr(cfs_rq);
|
|
resched_task(curr);
|
|
return;
|
|
}
|
|
if (is_same_group(curr, p)) {
|
|
s64 delta = curr->se.vruntime - p->se.vruntime;
|
|
|
|
if (delta > (s64)sysctl_sched_wakeup_granularity)
|
|
resched_task(curr);
|
|
}
|
|
}
|
|
|
|
static struct task_struct *pick_next_task_fair(struct rq *rq)
|
|
{
|
|
struct cfs_rq *cfs_rq = &rq->cfs;
|
|
struct sched_entity *se;
|
|
|
|
if (unlikely(!cfs_rq->nr_running))
|
|
return NULL;
|
|
|
|
do {
|
|
se = pick_next_entity(cfs_rq);
|
|
cfs_rq = group_cfs_rq(se);
|
|
} while (cfs_rq);
|
|
|
|
return task_of(se);
|
|
}
|
|
|
|
/*
|
|
* Account for a descheduled task:
|
|
*/
|
|
static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
|
|
{
|
|
struct sched_entity *se = &prev->se;
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
put_prev_entity(cfs_rq, se);
|
|
}
|
|
}
|
|
|
|
/**************************************************
|
|
* Fair scheduling class load-balancing methods:
|
|
*/
|
|
|
|
/*
|
|
* Load-balancing iterator. Note: while the runqueue stays locked
|
|
* during the whole iteration, the current task might be
|
|
* dequeued so the iterator has to be dequeue-safe. Here we
|
|
* achieve that by always pre-iterating before returning
|
|
* the current task:
|
|
*/
|
|
static inline struct task_struct *
|
|
__load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr)
|
|
{
|
|
struct task_struct *p;
|
|
|
|
if (!curr)
|
|
return NULL;
|
|
|
|
p = rb_entry(curr, struct task_struct, se.run_node);
|
|
cfs_rq->rb_load_balance_curr = rb_next(curr);
|
|
|
|
return p;
|
|
}
|
|
|
|
static struct task_struct *load_balance_start_fair(void *arg)
|
|
{
|
|
struct cfs_rq *cfs_rq = arg;
|
|
|
|
return __load_balance_iterator(cfs_rq, first_fair(cfs_rq));
|
|
}
|
|
|
|
static struct task_struct *load_balance_next_fair(void *arg)
|
|
{
|
|
struct cfs_rq *cfs_rq = arg;
|
|
|
|
return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static int cfs_rq_best_prio(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *curr;
|
|
struct task_struct *p;
|
|
|
|
if (!cfs_rq->nr_running)
|
|
return MAX_PRIO;
|
|
|
|
curr = __pick_next_entity(cfs_rq);
|
|
p = task_of(curr);
|
|
|
|
return p->prio;
|
|
}
|
|
#endif
|
|
|
|
static unsigned long
|
|
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_nr_move, unsigned long max_load_move,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *all_pinned, int *this_best_prio)
|
|
{
|
|
struct cfs_rq *busy_cfs_rq;
|
|
unsigned long load_moved, total_nr_moved = 0, nr_moved;
|
|
long rem_load_move = max_load_move;
|
|
struct rq_iterator cfs_rq_iterator;
|
|
|
|
cfs_rq_iterator.start = load_balance_start_fair;
|
|
cfs_rq_iterator.next = load_balance_next_fair;
|
|
|
|
for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
struct cfs_rq *this_cfs_rq;
|
|
long imbalance;
|
|
unsigned long maxload;
|
|
|
|
this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu);
|
|
|
|
imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight;
|
|
/* Don't pull if this_cfs_rq has more load than busy_cfs_rq */
|
|
if (imbalance <= 0)
|
|
continue;
|
|
|
|
/* Don't pull more than imbalance/2 */
|
|
imbalance /= 2;
|
|
maxload = min(rem_load_move, imbalance);
|
|
|
|
*this_best_prio = cfs_rq_best_prio(this_cfs_rq);
|
|
#else
|
|
# define maxload rem_load_move
|
|
#endif
|
|
/* pass busy_cfs_rq argument into
|
|
* load_balance_[start|next]_fair iterators
|
|
*/
|
|
cfs_rq_iterator.arg = busy_cfs_rq;
|
|
nr_moved = balance_tasks(this_rq, this_cpu, busiest,
|
|
max_nr_move, maxload, sd, idle, all_pinned,
|
|
&load_moved, this_best_prio, &cfs_rq_iterator);
|
|
|
|
total_nr_moved += nr_moved;
|
|
max_nr_move -= nr_moved;
|
|
rem_load_move -= load_moved;
|
|
|
|
if (max_nr_move <= 0 || rem_load_move <= 0)
|
|
break;
|
|
}
|
|
|
|
return max_load_move - rem_load_move;
|
|
}
|
|
|
|
/*
|
|
* scheduler tick hitting a task of our scheduling class:
|
|
*/
|
|
static void task_tick_fair(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &curr->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
entity_tick(cfs_rq, se);
|
|
}
|
|
}
|
|
|
|
#define swap(a,b) do { typeof(a) tmp = (a); (a) = (b); (b) = tmp; } while (0)
|
|
|
|
/*
|
|
* Share the fairness runtime between parent and child, thus the
|
|
* total amount of pressure for CPU stays equal - new tasks
|
|
* get a chance to run but frequent forkers are not allowed to
|
|
* monopolize the CPU. Note: the parent runqueue is locked,
|
|
* the child is not running yet.
|
|
*/
|
|
static void task_new_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
struct sched_entity *se = &p->se, *curr = cfs_rq->curr;
|
|
|
|
sched_info_queued(p);
|
|
|
|
update_curr(cfs_rq);
|
|
place_entity(cfs_rq, se, 1);
|
|
|
|
if (sysctl_sched_child_runs_first &&
|
|
curr->vruntime < se->vruntime) {
|
|
/*
|
|
* Upon rescheduling, sched_class::put_prev_task() will place
|
|
* 'current' within the tree based on its new key value.
|
|
*/
|
|
swap(curr->vruntime, se->vruntime);
|
|
}
|
|
|
|
update_stats_enqueue(cfs_rq, se);
|
|
__enqueue_entity(cfs_rq, se);
|
|
account_entity_enqueue(cfs_rq, se);
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/* Account for a task changing its policy or group.
|
|
*
|
|
* This routine is mostly called to set cfs_rq->curr field when a task
|
|
* migrates between groups/classes.
|
|
*/
|
|
static void set_curr_task_fair(struct rq *rq)
|
|
{
|
|
struct sched_entity *se = &rq->curr->se;
|
|
|
|
for_each_sched_entity(se)
|
|
set_next_entity(cfs_rq_of(se), se);
|
|
}
|
|
#else
|
|
static void set_curr_task_fair(struct rq *rq)
|
|
{
|
|
struct sched_entity *se = &rq->curr->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
cfs_rq->curr = se;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* All the scheduling class methods:
|
|
*/
|
|
struct sched_class fair_sched_class __read_mostly = {
|
|
.enqueue_task = enqueue_task_fair,
|
|
.dequeue_task = dequeue_task_fair,
|
|
.yield_task = yield_task_fair,
|
|
|
|
.check_preempt_curr = check_preempt_wakeup,
|
|
|
|
.pick_next_task = pick_next_task_fair,
|
|
.put_prev_task = put_prev_task_fair,
|
|
|
|
.load_balance = load_balance_fair,
|
|
|
|
.set_curr_task = set_curr_task_fair,
|
|
.task_tick = task_tick_fair,
|
|
.task_new = task_new_fair,
|
|
};
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
static void print_cfs_stats(struct seq_file *m, int cpu)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
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for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
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print_cfs_rq(m, cpu, cfs_rq);
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}
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#endif
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