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9f508f8258
cleanup: we have the 'se' and 'curr' entity-pointers already, no need to use p->se and current->se. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mike Galbraith <efault@gmx.de>
1180 lines
29 KiB
C
1180 lines
29 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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unsigned int sysctl_sched_latency __read_mostly = 20000000ULL;
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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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* 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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unsigned int sysctl_sched_batch_wakeup_granularity __read_mostly = 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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unsigned int sysctl_sched_wakeup_granularity __read_mostly = 1000000UL;
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unsigned int sysctl_sched_stat_granularity __read_mostly;
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/*
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* Initialized in sched_init_granularity() [to 5 times the base granularity]:
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*/
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unsigned int sysctl_sched_runtime_limit __read_mostly;
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/*
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* Debugging: various feature bits
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*/
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enum {
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SCHED_FEAT_FAIR_SLEEPERS = 1,
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SCHED_FEAT_SLEEPER_AVG = 2,
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SCHED_FEAT_SLEEPER_LOAD_AVG = 4,
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SCHED_FEAT_PRECISE_CPU_LOAD = 8,
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SCHED_FEAT_START_DEBIT = 16,
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SCHED_FEAT_SKIP_INITIAL = 32,
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};
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unsigned int sysctl_sched_features __read_mostly =
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SCHED_FEAT_FAIR_SLEEPERS *1 |
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SCHED_FEAT_SLEEPER_AVG *0 |
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SCHED_FEAT_SLEEPER_LOAD_AVG *1 |
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SCHED_FEAT_PRECISE_CPU_LOAD *1 |
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SCHED_FEAT_START_DEBIT *1 |
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SCHED_FEAT_SKIP_INITIAL *0;
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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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/* currently running entity (if any) on this cfs_rq */
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static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->curr;
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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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static inline void
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set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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cfs_rq->curr = se;
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}
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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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static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq)
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{
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struct rq *rq = rq_of(cfs_rq);
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if (unlikely(rq->curr->sched_class != &fair_sched_class))
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return NULL;
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return &rq->curr->se;
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}
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#define entity_is_task(se) 1
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static inline void
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set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
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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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/*
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* Enqueue an entity into the rb-tree:
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*/
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static inline 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 = se->fair_key;
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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 - entry->fair_key < 0) {
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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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cfs_rq->rb_leftmost = &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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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 inline 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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cfs_rq->rb_leftmost = rb_next(&se->run_node);
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rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
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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 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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/**************************************************************
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* Scheduling class statistics methods:
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*/
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/*
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* Calculate the preemption granularity needed to schedule every
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* runnable task once per sysctl_sched_latency amount of time.
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* (down to a sensible low limit on granularity)
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*
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* For example, if there are 2 tasks running and latency is 10 msecs,
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* we switch tasks every 5 msecs. If we have 3 tasks running, we have
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* to switch tasks every 3.33 msecs to get a 10 msecs observed latency
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* for each task. We do finer and finer scheduling up to until we
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* reach the minimum granularity value.
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*
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* To achieve this we use the following dynamic-granularity rule:
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*
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* gran = lat/nr - lat/nr/nr
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*
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* This comes out of the following equations:
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*
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* kA1 + gran = kB1
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* kB2 + gran = kA2
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* kA2 = kA1
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* kB2 = kB1 - d + d/nr
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* lat = d * nr
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*
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* Where 'k' is key, 'A' is task A (waiting), 'B' is task B (running),
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* '1' is start of time, '2' is end of time, 'd' is delay between
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* 1 and 2 (during which task B was running), 'nr' is number of tasks
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* running, 'lat' is the the period of each task. ('lat' is the
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* sched_latency that we aim for.)
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*/
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static long
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sched_granularity(struct cfs_rq *cfs_rq)
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{
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unsigned int gran = sysctl_sched_latency;
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unsigned int nr = cfs_rq->nr_running;
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if (nr > 1) {
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gran = gran/nr - gran/nr/nr;
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gran = max(gran, sysctl_sched_min_granularity);
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}
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return gran;
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}
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/*
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* We rescale the rescheduling granularity of tasks according to their
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* nice level, but only linearly, not exponentially:
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*/
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static long
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niced_granularity(struct sched_entity *curr, unsigned long granularity)
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{
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u64 tmp;
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if (likely(curr->load.weight == NICE_0_LOAD))
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return granularity;
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/*
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* Positive nice levels get the same granularity as nice-0:
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*/
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if (likely(curr->load.weight < NICE_0_LOAD)) {
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tmp = curr->load.weight * (u64)granularity;
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return (long) (tmp >> NICE_0_SHIFT);
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}
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/*
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* Negative nice level tasks get linearly finer
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* granularity:
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*/
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tmp = curr->load.inv_weight * (u64)granularity;
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/*
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* It will always fit into 'long':
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*/
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return (long) (tmp >> WMULT_SHIFT);
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}
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static inline void
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limit_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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long limit = sysctl_sched_runtime_limit;
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/*
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* Niced tasks have the same history dynamic range as
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* non-niced tasks:
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*/
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if (unlikely(se->wait_runtime > limit)) {
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se->wait_runtime = limit;
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schedstat_inc(se, wait_runtime_overruns);
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schedstat_inc(cfs_rq, wait_runtime_overruns);
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}
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if (unlikely(se->wait_runtime < -limit)) {
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se->wait_runtime = -limit;
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schedstat_inc(se, wait_runtime_underruns);
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schedstat_inc(cfs_rq, wait_runtime_underruns);
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}
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}
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static inline void
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__add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
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{
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se->wait_runtime += delta;
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schedstat_add(se, sum_wait_runtime, delta);
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limit_wait_runtime(cfs_rq, se);
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}
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static void
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add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta)
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{
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schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime);
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__add_wait_runtime(cfs_rq, se, delta);
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schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
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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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{
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unsigned long delta, delta_exec, delta_fair, delta_mine;
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struct load_weight *lw = &cfs_rq->load;
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unsigned long load = lw->weight;
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delta_exec = curr->delta_exec;
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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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cfs_rq->exec_clock += delta_exec;
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if (unlikely(!load))
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return;
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delta_fair = calc_delta_fair(delta_exec, lw);
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delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw);
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if (cfs_rq->sleeper_bonus > sysctl_sched_min_granularity) {
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delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);
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delta = min(delta, (unsigned long)(
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(long)sysctl_sched_runtime_limit - curr->wait_runtime));
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cfs_rq->sleeper_bonus -= delta;
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delta_mine -= delta;
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}
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cfs_rq->fair_clock += delta_fair;
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/*
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* We executed delta_exec amount of time on the CPU,
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* but we were only entitled to delta_mine amount of
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* time during that period (if nr_running == 1 then
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* the two values are equal)
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* [Note: delta_mine - delta_exec is negative]:
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*/
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add_wait_runtime(cfs_rq, curr, delta_mine - delta_exec);
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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(cfs_rq);
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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)(rq_of(cfs_rq)->clock - curr->exec_start);
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curr->delta_exec += delta_exec;
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if (unlikely(curr->delta_exec > sysctl_sched_stat_granularity)) {
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__update_curr(cfs_rq, curr);
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curr->delta_exec = 0;
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}
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curr->exec_start = rq_of(cfs_rq)->clock;
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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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se->wait_start_fair = cfs_rq->fair_clock;
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schedstat_set(se->wait_start, rq_of(cfs_rq)->clock);
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}
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/*
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* We calculate fair deltas here, so protect against the random effects
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* of a multiplication overflow by capping it to the runtime limit:
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*/
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#if BITS_PER_LONG == 32
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static inline unsigned long
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calc_weighted(unsigned long delta, unsigned long weight, int shift)
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{
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u64 tmp = (u64)delta * weight >> shift;
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if (unlikely(tmp > sysctl_sched_runtime_limit*2))
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return sysctl_sched_runtime_limit*2;
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return tmp;
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}
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#else
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static inline unsigned long
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calc_weighted(unsigned long delta, unsigned long weight, int shift)
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{
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return delta * weight >> shift;
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}
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#endif
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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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s64 key;
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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(cfs_rq))
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update_stats_wait_start(cfs_rq, se);
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/*
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* Update the key:
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*/
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key = cfs_rq->fair_clock;
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/*
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* Optimize the common nice 0 case:
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*/
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if (likely(se->load.weight == NICE_0_LOAD)) {
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key -= se->wait_runtime;
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} else {
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u64 tmp;
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if (se->wait_runtime < 0) {
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tmp = -se->wait_runtime;
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key += (tmp * se->load.inv_weight) >>
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(WMULT_SHIFT - NICE_0_SHIFT);
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} else {
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tmp = se->wait_runtime;
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key -= (tmp * se->load.inv_weight) >>
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(WMULT_SHIFT - NICE_0_SHIFT);
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}
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}
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se->fair_key = key;
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}
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/*
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* Note: must be called with a freshly updated rq->fair_clock.
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*/
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static inline 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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unsigned long delta_fair = se->delta_fair_run;
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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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if (unlikely(se->load.weight != NICE_0_LOAD))
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delta_fair = calc_weighted(delta_fair, se->load.weight,
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NICE_0_SHIFT);
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add_wait_runtime(cfs_rq, se, delta_fair);
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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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unsigned long delta_fair;
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if (unlikely(!se->wait_start_fair))
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return;
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delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
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(u64)(cfs_rq->fair_clock - se->wait_start_fair));
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se->delta_fair_run += delta_fair;
|
|
if (unlikely(abs(se->delta_fair_run) >=
|
|
sysctl_sched_stat_granularity)) {
|
|
__update_stats_wait_end(cfs_rq, se);
|
|
se->delta_fair_run = 0;
|
|
}
|
|
|
|
se->wait_start_fair = 0;
|
|
schedstat_set(se->wait_start, 0);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_curr(cfs_rq);
|
|
/*
|
|
* Mark the end of the wait period if dequeueing a
|
|
* waiting task:
|
|
*/
|
|
if (se != cfs_rq_curr(cfs_rq))
|
|
update_stats_wait_end(cfs_rq, se);
|
|
}
|
|
|
|
/*
|
|
* We are picking a new current task - update its stats:
|
|
*/
|
|
static inline void
|
|
update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* We are starting a new run period:
|
|
*/
|
|
se->exec_start = rq_of(cfs_rq)->clock;
|
|
}
|
|
|
|
/*
|
|
* We are descheduling a task - update its stats:
|
|
*/
|
|
static inline void
|
|
update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
se->exec_start = 0;
|
|
}
|
|
|
|
/**************************************************
|
|
* Scheduling class queueing methods:
|
|
*/
|
|
|
|
static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
unsigned long load = cfs_rq->load.weight, delta_fair;
|
|
long prev_runtime;
|
|
|
|
/*
|
|
* Do not boost sleepers if there's too much bonus 'in flight'
|
|
* already:
|
|
*/
|
|
if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit))
|
|
return;
|
|
|
|
if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG)
|
|
load = rq_of(cfs_rq)->cpu_load[2];
|
|
|
|
delta_fair = se->delta_fair_sleep;
|
|
|
|
/*
|
|
* Fix up delta_fair with the effect of us running
|
|
* during the whole sleep period:
|
|
*/
|
|
if (sysctl_sched_features & SCHED_FEAT_SLEEPER_AVG)
|
|
delta_fair = div64_likely32((u64)delta_fair * load,
|
|
load + se->load.weight);
|
|
|
|
if (unlikely(se->load.weight != NICE_0_LOAD))
|
|
delta_fair = calc_weighted(delta_fair, se->load.weight,
|
|
NICE_0_SHIFT);
|
|
|
|
prev_runtime = se->wait_runtime;
|
|
__add_wait_runtime(cfs_rq, se, delta_fair);
|
|
schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
|
|
delta_fair = se->wait_runtime - prev_runtime;
|
|
|
|
/*
|
|
* Track the amount of bonus we've given to sleepers:
|
|
*/
|
|
cfs_rq->sleeper_bonus += delta_fair;
|
|
}
|
|
|
|
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
struct task_struct *tsk = task_of(se);
|
|
unsigned long delta_fair;
|
|
|
|
if ((entity_is_task(se) && tsk->policy == SCHED_BATCH) ||
|
|
!(sysctl_sched_features & SCHED_FEAT_FAIR_SLEEPERS))
|
|
return;
|
|
|
|
delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit),
|
|
(u64)(cfs_rq->fair_clock - se->sleep_start_fair));
|
|
|
|
se->delta_fair_sleep += delta_fair;
|
|
if (unlikely(abs(se->delta_fair_sleep) >=
|
|
sysctl_sched_stat_granularity)) {
|
|
__enqueue_sleeper(cfs_rq, se);
|
|
se->delta_fair_sleep = 0;
|
|
}
|
|
|
|
se->sleep_start_fair = 0;
|
|
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (se->sleep_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
|
|
|
|
if ((s64)delta < 0)
|
|
delta = 0;
|
|
|
|
if (unlikely(delta > se->sleep_max))
|
|
se->sleep_max = delta;
|
|
|
|
se->sleep_start = 0;
|
|
se->sum_sleep_runtime += delta;
|
|
}
|
|
if (se->block_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->block_start;
|
|
|
|
if ((s64)delta < 0)
|
|
delta = 0;
|
|
|
|
if (unlikely(delta > se->block_max))
|
|
se->block_max = delta;
|
|
|
|
se->block_start = 0;
|
|
se->sum_sleep_runtime += delta;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
|
|
{
|
|
/*
|
|
* Update the fair clock.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
if (wakeup)
|
|
enqueue_sleeper(cfs_rq, se);
|
|
|
|
update_stats_enqueue(cfs_rq, se);
|
|
__enqueue_entity(cfs_rq, se);
|
|
}
|
|
|
|
static void
|
|
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
|
|
{
|
|
update_stats_dequeue(cfs_rq, se);
|
|
if (sleep) {
|
|
se->sleep_start_fair = cfs_rq->fair_clock;
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (entity_is_task(se)) {
|
|
struct task_struct *tsk = task_of(se);
|
|
|
|
if (tsk->state & TASK_INTERRUPTIBLE)
|
|
se->sleep_start = rq_of(cfs_rq)->clock;
|
|
if (tsk->state & TASK_UNINTERRUPTIBLE)
|
|
se->block_start = rq_of(cfs_rq)->clock;
|
|
}
|
|
cfs_rq->wait_runtime -= se->wait_runtime;
|
|
#endif
|
|
}
|
|
__dequeue_entity(cfs_rq, se);
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static int
|
|
__check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se,
|
|
struct sched_entity *curr, unsigned long granularity)
|
|
{
|
|
s64 __delta = curr->fair_key - se->fair_key;
|
|
|
|
/*
|
|
* Take scheduling granularity into account - do not
|
|
* preempt the current task unless the best task has
|
|
* a larger than sched_granularity fairness advantage:
|
|
*/
|
|
if (__delta > niced_granularity(curr, granularity)) {
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
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. (note, here we rely on pick_next_task() having
|
|
* done a put_prev_task_fair() shortly before this, which
|
|
* updated rq->fair_clock - used by update_stats_wait_end())
|
|
*/
|
|
update_stats_wait_end(cfs_rq, se);
|
|
update_stats_curr_start(cfs_rq, se);
|
|
set_cfs_rq_curr(cfs_rq, se);
|
|
}
|
|
|
|
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *se = __pick_next_entity(cfs_rq);
|
|
|
|
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);
|
|
set_cfs_rq_curr(cfs_rq, NULL);
|
|
}
|
|
|
|
static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
|
|
{
|
|
unsigned long gran, ideal_runtime, delta_exec;
|
|
struct sched_entity *next;
|
|
|
|
/*
|
|
* Dequeue and enqueue the task to update its
|
|
* position within the tree:
|
|
*/
|
|
dequeue_entity(cfs_rq, curr, 0);
|
|
enqueue_entity(cfs_rq, curr, 0);
|
|
|
|
/*
|
|
* Reschedule if another task tops the current one.
|
|
*/
|
|
next = __pick_next_entity(cfs_rq);
|
|
if (next == curr)
|
|
return;
|
|
|
|
gran = sched_granularity(cfs_rq);
|
|
ideal_runtime = niced_granularity(curr,
|
|
max(sysctl_sched_latency / cfs_rq->nr_running,
|
|
(unsigned long)sysctl_sched_min_granularity));
|
|
/*
|
|
* If we executed more than what the latency constraint suggests,
|
|
* reduce the rescheduling granularity. This way the total latency
|
|
* of how much a task is not scheduled converges to
|
|
* sysctl_sched_latency:
|
|
*/
|
|
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
|
|
if (delta_exec > ideal_runtime)
|
|
gran = 0;
|
|
|
|
if (__check_preempt_curr_fair(cfs_rq, next, curr, gran))
|
|
curr->prev_sum_exec_runtime = curr->sum_exec_runtime;
|
|
}
|
|
|
|
/**************************************************
|
|
* 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)
|
|
{
|
|
/* A later patch will take group into account */
|
|
return &cpu_rq(this_cpu)->cfs;
|
|
}
|
|
|
|
/* 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
|
|
*/
|
|
static void yield_task_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
|
|
__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);
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
unsigned long gran;
|
|
|
|
if (unlikely(rt_prio(p->prio))) {
|
|
update_rq_clock(rq);
|
|
update_curr(cfs_rq);
|
|
resched_task(curr);
|
|
return;
|
|
}
|
|
|
|
gran = sysctl_sched_wakeup_granularity;
|
|
/*
|
|
* Batch tasks prefer throughput over latency:
|
|
*/
|
|
if (unlikely(p->policy == SCHED_BATCH))
|
|
gran = sysctl_sched_batch_wakeup_granularity;
|
|
|
|
if (is_same_group(curr, p))
|
|
__check_preempt_curr_fair(cfs_rq, &p->se, &curr->se, gran);
|
|
}
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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(cfs_rq);
|
|
|
|
sched_info_queued(p);
|
|
|
|
update_curr(cfs_rq);
|
|
update_stats_enqueue(cfs_rq, se);
|
|
/*
|
|
* Child runs first: we let it run before the parent
|
|
* until it reschedules once. We set up the key so that
|
|
* it will preempt the parent:
|
|
*/
|
|
se->fair_key = curr->fair_key -
|
|
niced_granularity(curr, sched_granularity(cfs_rq)) - 1;
|
|
/*
|
|
* The first wait is dominated by the child-runs-first logic,
|
|
* so do not credit it with that waiting time yet:
|
|
*/
|
|
if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL)
|
|
se->wait_start_fair = 0;
|
|
|
|
/*
|
|
* The statistical average of wait_runtime is about
|
|
* -granularity/2, so initialize the task with that:
|
|
*/
|
|
if (sysctl_sched_features & SCHED_FEAT_START_DEBIT) {
|
|
se->wait_runtime = -(sched_granularity(cfs_rq) / 2);
|
|
schedstat_add(cfs_rq, wait_runtime, se->wait_runtime);
|
|
}
|
|
|
|
__enqueue_entity(cfs_rq, se);
|
|
}
|
|
|
|
#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)
|
|
{
|
|
}
|
|
#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_curr_fair,
|
|
|
|
.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;
|
|
|
|
for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
|
|
print_cfs_rq(m, cpu, cfs_rq);
|
|
}
|
|
#endif
|