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https://github.com/edk2-porting/linux-next.git
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77ae651347
Defer commit6d299f1b53
to the next release. Testing of the tip/sched/clock tree revealed a mysql+oltp regression which bisection eventually traced back to this commit in mainline. Pertinent test results: Three run sysbench averages, throughput units in read/write requests/sec. clients 1 2 4 8 16 32 646e0534f
9646 17876 34774 33868 32230 30767 29441 2.6.26.1 9112 17936 34652 33383 31929 30665 292326d299f1
9112 14637 28370 33339 32038 30762 29204 Note: subsequent commits hide the majority of this regression until you apply the clock fixes, at which time it reemerges at full magnitude. We cannot see anything bad about the change itself so we defer it to the next release until this problem is fully analysed. Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
1733 lines
40 KiB
C
1733 lines
40 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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#include <linux/latencytop.h>
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/*
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* Targeted preemption latency for CPU-bound tasks:
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* (default: 20ms * (1 + ilog(ncpus)), 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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* and have no persistent notion like in traditional, time-slice
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* based scheduling concepts.
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*
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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 (cs) field)
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*/
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unsigned int sysctl_sched_latency = 20000000ULL;
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/*
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* Minimal preemption granularity for CPU-bound tasks:
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* (default: 4 msec * (1 + ilog(ncpus)), units: nanoseconds)
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*/
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unsigned int sysctl_sched_min_granularity = 4000000ULL;
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/*
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* is kept at sysctl_sched_latency / sysctl_sched_min_granularity
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*/
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static unsigned int sched_nr_latency = 5;
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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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* 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_OTHER wake-up granularity.
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* (default: 5 msec * (1 + ilog(ncpus)), 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 = 5000000UL;
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const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
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/**************************************************************
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* CFS operations on generic schedulable entities:
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*/
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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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#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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/* Walk up scheduling entities hierarchy */
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#define for_each_sched_entity(se) \
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for (; se; se = se->parent)
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static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
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{
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return p->se.cfs_rq;
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}
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/* runqueue on which this entity is (to be) queued */
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static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
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{
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return se->cfs_rq;
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}
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/* runqueue "owned" by this group */
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static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
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{
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return grp->my_q;
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}
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/* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on
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* another cpu ('this_cpu')
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*/
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static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
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{
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return cfs_rq->tg->cfs_rq[this_cpu];
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}
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/* Iterate thr' all leaf cfs_rq's on a runqueue */
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#define for_each_leaf_cfs_rq(rq, cfs_rq) \
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list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
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/* Do the two (enqueued) entities belong to the same group ? */
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static inline int
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is_same_group(struct sched_entity *se, struct sched_entity *pse)
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{
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if (se->cfs_rq == pse->cfs_rq)
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return 1;
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return 0;
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}
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static inline struct sched_entity *parent_entity(struct sched_entity *se)
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{
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return se->parent;
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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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#define entity_is_task(se) 1
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#define for_each_sched_entity(se) \
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for (; se; se = NULL)
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static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
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{
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return &task_rq(p)->cfs;
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}
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static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
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{
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struct task_struct *p = task_of(se);
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struct rq *rq = task_rq(p);
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return &rq->cfs;
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}
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/* runqueue "owned" by this group */
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static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
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{
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return NULL;
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}
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static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu)
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{
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return &cpu_rq(this_cpu)->cfs;
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}
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#define for_each_leaf_cfs_rq(rq, cfs_rq) \
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for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
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static inline int
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is_same_group(struct sched_entity *se, struct sched_entity *pse)
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{
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return 1;
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}
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static inline struct sched_entity *parent_entity(struct sched_entity *se)
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{
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return NULL;
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}
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#endif /* CONFIG_FAIR_GROUP_SCHED */
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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 max_vruntime(u64 min_vruntime, u64 vruntime)
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{
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s64 delta = (s64)(vruntime - min_vruntime);
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if (delta > 0)
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min_vruntime = vruntime;
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return min_vruntime;
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}
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static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
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{
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s64 delta = (s64)(vruntime - min_vruntime);
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if (delta < 0)
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min_vruntime = vruntime;
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return min_vruntime;
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}
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static inline s64 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 __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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cfs_rq->rb_leftmost = &se->run_node;
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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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cfs_rq->min_vruntime =
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max_vruntime(cfs_rq->min_vruntime, se->vruntime);
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}
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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 __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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struct rb_node *next_node;
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struct sched_entity *next;
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next_node = rb_next(&se->run_node);
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cfs_rq->rb_leftmost = next_node;
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if (next_node) {
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next = rb_entry(next_node,
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struct sched_entity, run_node);
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cfs_rq->min_vruntime =
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max_vruntime(cfs_rq->min_vruntime,
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next->vruntime);
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}
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}
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if (cfs_rq->next == se)
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cfs_rq->next = NULL;
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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 *last = rb_last(&cfs_rq->tasks_timeline);
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if (!last)
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return NULL;
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return rb_entry(last, 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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#ifdef CONFIG_SCHED_DEBUG
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int sched_nr_latency_handler(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
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if (ret || !write)
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return ret;
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sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
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sysctl_sched_min_granularity);
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return 0;
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}
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#endif
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/*
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* delta *= w / rw
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*/
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static inline unsigned long
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calc_delta_weight(unsigned long delta, struct sched_entity *se)
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{
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for_each_sched_entity(se) {
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delta = calc_delta_mine(delta,
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se->load.weight, &cfs_rq_of(se)->load);
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}
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return delta;
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}
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/*
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* delta *= rw / w
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*/
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static inline unsigned long
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calc_delta_fair(unsigned long delta, struct sched_entity *se)
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{
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for_each_sched_entity(se) {
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delta = calc_delta_mine(delta,
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cfs_rq_of(se)->load.weight, &se->load);
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}
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return delta;
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}
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/*
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* The idea is to set a period in which each task runs once.
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*
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* When there are too many tasks (sysctl_sched_nr_latency) we have to stretch
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* this period because otherwise the slices get too small.
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*
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* p = (nr <= nl) ? l : l*nr/nl
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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 = sched_nr_latency;
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if (unlikely(nr_running > nr_latency)) {
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period = sysctl_sched_min_granularity;
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period *= nr_running;
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}
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return period;
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}
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/*
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* We calculate the wall-time slice from the period by taking a part
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* proportional to the weight.
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*
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* s = p*w/rw
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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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return calc_delta_weight(__sched_period(cfs_rq->nr_running), se);
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}
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/*
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* We calculate the vruntime slice of a to be inserted task
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*
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* vs = s*rw/w = p
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*/
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static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se)
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{
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unsigned long nr_running = cfs_rq->nr_running;
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if (!se->on_rq)
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nr_running++;
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return __sched_period(nr_running);
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}
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/*
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* The goal of calc_delta_asym() is to be asymmetrically around NICE_0_LOAD, in
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* that it favours >=0 over <0.
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*
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* -20 |
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* |
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* 0 --------+-------
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* .'
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* 19 .'
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*
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*/
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static unsigned long
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calc_delta_asym(unsigned long delta, struct sched_entity *se)
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{
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struct load_weight lw = {
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.weight = NICE_0_LOAD,
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.inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT)
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};
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for_each_sched_entity(se) {
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struct load_weight *se_lw = &se->load;
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unsigned long rw = cfs_rq_of(se)->load.weight;
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#ifdef CONFIG_FAIR_SCHED_GROUP
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struct cfs_rq *cfs_rq = se->my_q;
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struct task_group *tg = NULL
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if (cfs_rq)
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tg = cfs_rq->tg;
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if (tg && tg->shares < NICE_0_LOAD) {
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/*
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* scale shares to what it would have been had
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* tg->weight been NICE_0_LOAD:
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*
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* weight = 1024 * shares / tg->weight
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*/
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lw.weight *= se->load.weight;
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lw.weight /= tg->shares;
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lw.inv_weight = 0;
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se_lw = &lw;
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rw += lw.weight - se->load.weight;
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} else
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#endif
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if (se->load.weight < NICE_0_LOAD) {
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se_lw = &lw;
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rw += NICE_0_LOAD - se->load.weight;
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}
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delta = calc_delta_mine(delta, rw, se_lw);
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}
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return delta;
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}
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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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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 = calc_delta_fair(delta_exec, curr);
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curr->vruntime += delta_exec_weighted;
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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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|
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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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if (entity_is_task(curr)) {
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struct task_struct *curtask = task_of(curr);
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cpuacct_charge(curtask, delta_exec);
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}
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}
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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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|
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/*
|
|
* Task is being enqueued - update stats:
|
|
*/
|
|
static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* Are we enqueueing a waiting task? (for current tasks
|
|
* a dequeue/enqueue event is a NOP)
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
update_stats_wait_start(cfs_rq, se);
|
|
}
|
|
|
|
static void
|
|
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
schedstat_set(se->wait_max, max(se->wait_max,
|
|
rq_of(cfs_rq)->clock - se->wait_start));
|
|
schedstat_set(se->wait_count, se->wait_count + 1);
|
|
schedstat_set(se->wait_sum, se->wait_sum +
|
|
rq_of(cfs_rq)->clock - se->wait_start);
|
|
schedstat_set(se->wait_start, 0);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* Mark the end of the wait period if dequeueing a
|
|
* waiting task:
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
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;
|
|
}
|
|
|
|
/**************************************************
|
|
* Scheduling class queueing methods:
|
|
*/
|
|
|
|
#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED
|
|
static void
|
|
add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
|
|
{
|
|
cfs_rq->task_weight += weight;
|
|
}
|
|
#else
|
|
static inline void
|
|
add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static void
|
|
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_add(&cfs_rq->load, se->load.weight);
|
|
if (!parent_entity(se))
|
|
inc_cpu_load(rq_of(cfs_rq), se->load.weight);
|
|
if (entity_is_task(se))
|
|
add_cfs_task_weight(cfs_rq, se->load.weight);
|
|
cfs_rq->nr_running++;
|
|
se->on_rq = 1;
|
|
list_add(&se->group_node, &cfs_rq->tasks);
|
|
}
|
|
|
|
static void
|
|
account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_sub(&cfs_rq->load, se->load.weight);
|
|
if (!parent_entity(se))
|
|
dec_cpu_load(rq_of(cfs_rq), se->load.weight);
|
|
if (entity_is_task(se))
|
|
add_cfs_task_weight(cfs_rq, -se->load.weight);
|
|
cfs_rq->nr_running--;
|
|
se->on_rq = 0;
|
|
list_del_init(&se->group_node);
|
|
}
|
|
|
|
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (se->sleep_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->sleep_start;
|
|
struct task_struct *tsk = task_of(se);
|
|
|
|
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;
|
|
|
|
account_scheduler_latency(tsk, delta >> 10, 1);
|
|
}
|
|
if (se->block_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->block_start;
|
|
struct task_struct *tsk = task_of(se);
|
|
|
|
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;
|
|
|
|
/*
|
|
* Blocking time is in units of nanosecs, so shift by 20 to
|
|
* get a milliseconds-range estimation of the amount of
|
|
* time that the task spent sleeping:
|
|
*/
|
|
if (unlikely(prof_on == SLEEP_PROFILING)) {
|
|
|
|
profile_hits(SLEEP_PROFILING, (void *)get_wchan(tsk),
|
|
delta >> 20);
|
|
}
|
|
account_scheduler_latency(tsk, delta >> 10, 0);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
s64 d = se->vruntime - cfs_rq->min_vruntime;
|
|
|
|
if (d < 0)
|
|
d = -d;
|
|
|
|
if (d > 3*sysctl_sched_latency)
|
|
schedstat_inc(cfs_rq, nr_spread_over);
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
|
|
{
|
|
u64 vruntime;
|
|
|
|
if (first_fair(cfs_rq)) {
|
|
vruntime = min_vruntime(cfs_rq->min_vruntime,
|
|
__pick_next_entity(cfs_rq)->vruntime);
|
|
} else
|
|
vruntime = cfs_rq->min_vruntime;
|
|
|
|
/*
|
|
* The 'current' period is already promised to the current tasks,
|
|
* however the extra weight of the new task will slow them down a
|
|
* little, place the new task so that it fits in the slot that
|
|
* stays open at the end.
|
|
*/
|
|
if (initial && sched_feat(START_DEBIT))
|
|
vruntime += sched_vslice_add(cfs_rq, se);
|
|
|
|
if (!initial) {
|
|
/* sleeps upto a single latency don't count. */
|
|
if (sched_feat(NEW_FAIR_SLEEPERS)) {
|
|
unsigned long thresh = sysctl_sched_latency;
|
|
|
|
/*
|
|
* convert the sleeper threshold into virtual time
|
|
*/
|
|
if (sched_feat(NORMALIZED_SLEEPER))
|
|
thresh = calc_delta_fair(thresh, se);
|
|
|
|
vruntime -= thresh;
|
|
}
|
|
|
|
/* ensure we never gain time by being placed backwards. */
|
|
vruntime = max_vruntime(se->vruntime, vruntime);
|
|
}
|
|
|
|
se->vruntime = vruntime;
|
|
}
|
|
|
|
static void
|
|
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
account_entity_enqueue(cfs_rq, se);
|
|
|
|
if (wakeup) {
|
|
place_entity(cfs_rq, se, 0);
|
|
enqueue_sleeper(cfs_rq, se);
|
|
}
|
|
|
|
update_stats_enqueue(cfs_rq, se);
|
|
check_spread(cfs_rq, se);
|
|
if (se != cfs_rq->curr)
|
|
__enqueue_entity(cfs_rq, se);
|
|
}
|
|
|
|
static void
|
|
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
update_stats_dequeue(cfs_rq, se);
|
|
if (sleep) {
|
|
#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;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
if (se != cfs_rq->curr)
|
|
__dequeue_entity(cfs_rq, se);
|
|
account_entity_dequeue(cfs_rq, se);
|
|
}
|
|
|
|
/*
|
|
* 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 void
|
|
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/* 'current' is not kept within the tree. */
|
|
if (se->on_rq) {
|
|
/*
|
|
* 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);
|
|
__dequeue_entity(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(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
u64 pair_slice = rq->clock - cfs_rq->pair_start;
|
|
|
|
if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) {
|
|
cfs_rq->pair_start = rq->clock;
|
|
return se;
|
|
}
|
|
|
|
return cfs_rq->next;
|
|
}
|
|
|
|
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *se = NULL;
|
|
|
|
if (first_fair(cfs_rq)) {
|
|
se = __pick_next_entity(cfs_rq);
|
|
se = pick_next(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);
|
|
|
|
check_spread(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, int queued)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
/*
|
|
* queued ticks are scheduled to match the slice, so don't bother
|
|
* validating it and just reschedule.
|
|
*/
|
|
if (queued) {
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
return;
|
|
}
|
|
/*
|
|
* don't let the period tick interfere with the hrtick preemption
|
|
*/
|
|
if (!sched_feat(DOUBLE_TICK) &&
|
|
hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
|
|
return;
|
|
#endif
|
|
|
|
if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT))
|
|
check_preempt_tick(cfs_rq, curr);
|
|
}
|
|
|
|
/**************************************************
|
|
* CFS operations on tasks:
|
|
*/
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
WARN_ON(task_rq(p) != rq);
|
|
|
|
if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
|
|
u64 slice = sched_slice(cfs_rq, se);
|
|
u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
|
|
s64 delta = slice - ran;
|
|
|
|
if (delta < 0) {
|
|
if (rq->curr == p)
|
|
resched_task(p);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Don't schedule slices shorter than 10000ns, that just
|
|
* doesn't make sense. Rely on vruntime for fairness.
|
|
*/
|
|
if (rq->curr != p)
|
|
delta = max_t(s64, 10000LL, delta);
|
|
|
|
hrtick_start(rq, delta);
|
|
}
|
|
}
|
|
#else /* !CONFIG_SCHED_HRTICK */
|
|
static inline void
|
|
hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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);
|
|
wakeup = 1;
|
|
}
|
|
|
|
hrtick_start_fair(rq, rq->curr);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
sleep = 1;
|
|
}
|
|
|
|
hrtick_start_fair(rq, rq->curr);
|
|
}
|
|
|
|
/*
|
|
* 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 *curr = rq->curr;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
struct sched_entity *rightmost, *se = &curr->se;
|
|
|
|
/*
|
|
* Are we the only task in the tree?
|
|
*/
|
|
if (unlikely(cfs_rq->nr_running == 1))
|
|
return;
|
|
|
|
if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
|
|
update_rq_clock(rq);
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
return;
|
|
}
|
|
/*
|
|
* Find the rightmost entry in the rbtree:
|
|
*/
|
|
rightmost = __pick_last_entity(cfs_rq);
|
|
/*
|
|
* Already in the rightmost position?
|
|
*/
|
|
if (unlikely(!rightmost || rightmost->vruntime < se->vruntime))
|
|
return;
|
|
|
|
/*
|
|
* Minimally necessary key value to be last in the tree:
|
|
* Upon rescheduling, sched_class::put_prev_task() will place
|
|
* 'current' within the tree based on its new key value.
|
|
*/
|
|
se->vruntime = rightmost->vruntime + 1;
|
|
}
|
|
|
|
/*
|
|
* wake_idle() will wake a task on an idle cpu if task->cpu is
|
|
* not idle and an idle cpu is available. The span of cpus to
|
|
* search starts with cpus closest then further out as needed,
|
|
* so we always favor a closer, idle cpu.
|
|
* Domains may include CPUs that are not usable for migration,
|
|
* hence we need to mask them out (cpu_active_map)
|
|
*
|
|
* Returns the CPU we should wake onto.
|
|
*/
|
|
#if defined(ARCH_HAS_SCHED_WAKE_IDLE)
|
|
static int wake_idle(int cpu, struct task_struct *p)
|
|
{
|
|
cpumask_t tmp;
|
|
struct sched_domain *sd;
|
|
int i;
|
|
|
|
/*
|
|
* If it is idle, then it is the best cpu to run this task.
|
|
*
|
|
* This cpu is also the best, if it has more than one task already.
|
|
* Siblings must be also busy(in most cases) as they didn't already
|
|
* pickup the extra load from this cpu and hence we need not check
|
|
* sibling runqueue info. This will avoid the checks and cache miss
|
|
* penalities associated with that.
|
|
*/
|
|
if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1)
|
|
return cpu;
|
|
|
|
for_each_domain(cpu, sd) {
|
|
if ((sd->flags & SD_WAKE_IDLE)
|
|
|| ((sd->flags & SD_WAKE_IDLE_FAR)
|
|
&& !task_hot(p, task_rq(p)->clock, sd))) {
|
|
cpus_and(tmp, sd->span, p->cpus_allowed);
|
|
cpus_and(tmp, tmp, cpu_active_map);
|
|
for_each_cpu_mask_nr(i, tmp) {
|
|
if (idle_cpu(i)) {
|
|
if (i != task_cpu(p)) {
|
|
schedstat_inc(p,
|
|
se.nr_wakeups_idle);
|
|
}
|
|
return i;
|
|
}
|
|
}
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
return cpu;
|
|
}
|
|
#else /* !ARCH_HAS_SCHED_WAKE_IDLE*/
|
|
static inline int wake_idle(int cpu, struct task_struct *p)
|
|
{
|
|
return cpu;
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
static const struct sched_class fair_sched_class;
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* effective_load() calculates the load change as seen from the root_task_group
|
|
*
|
|
* Adding load to a group doesn't make a group heavier, but can cause movement
|
|
* of group shares between cpus. Assuming the shares were perfectly aligned one
|
|
* can calculate the shift in shares.
|
|
*
|
|
* The problem is that perfectly aligning the shares is rather expensive, hence
|
|
* we try to avoid doing that too often - see update_shares(), which ratelimits
|
|
* this change.
|
|
*
|
|
* We compensate this by not only taking the current delta into account, but
|
|
* also considering the delta between when the shares were last adjusted and
|
|
* now.
|
|
*
|
|
* We still saw a performance dip, some tracing learned us that between
|
|
* cgroup:/ and cgroup:/foo balancing the number of affine wakeups increased
|
|
* significantly. Therefore try to bias the error in direction of failing
|
|
* the affine wakeup.
|
|
*
|
|
*/
|
|
static long effective_load(struct task_group *tg, int cpu,
|
|
long wl, long wg)
|
|
{
|
|
struct sched_entity *se = tg->se[cpu];
|
|
long more_w;
|
|
|
|
if (!tg->parent)
|
|
return wl;
|
|
|
|
/*
|
|
* By not taking the decrease of shares on the other cpu into
|
|
* account our error leans towards reducing the affine wakeups.
|
|
*/
|
|
if (!wl && sched_feat(ASYM_EFF_LOAD))
|
|
return wl;
|
|
|
|
/*
|
|
* Instead of using this increment, also add the difference
|
|
* between when the shares were last updated and now.
|
|
*/
|
|
more_w = se->my_q->load.weight - se->my_q->rq_weight;
|
|
wl += more_w;
|
|
wg += more_w;
|
|
|
|
for_each_sched_entity(se) {
|
|
#define D(n) (likely(n) ? (n) : 1)
|
|
|
|
long S, rw, s, a, b;
|
|
|
|
S = se->my_q->tg->shares;
|
|
s = se->my_q->shares;
|
|
rw = se->my_q->rq_weight;
|
|
|
|
a = S*(rw + wl);
|
|
b = S*rw + s*wg;
|
|
|
|
wl = s*(a-b)/D(b);
|
|
/*
|
|
* Assume the group is already running and will
|
|
* thus already be accounted for in the weight.
|
|
*
|
|
* That is, moving shares between CPUs, does not
|
|
* alter the group weight.
|
|
*/
|
|
wg = 0;
|
|
#undef D
|
|
}
|
|
|
|
return wl;
|
|
}
|
|
|
|
#else
|
|
|
|
static inline unsigned long effective_load(struct task_group *tg, int cpu,
|
|
unsigned long wl, unsigned long wg)
|
|
{
|
|
return wl;
|
|
}
|
|
|
|
#endif
|
|
|
|
static int
|
|
wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
|
|
struct task_struct *p, int prev_cpu, int this_cpu, int sync,
|
|
int idx, unsigned long load, unsigned long this_load,
|
|
unsigned int imbalance)
|
|
{
|
|
struct task_struct *curr = this_rq->curr;
|
|
struct task_group *tg;
|
|
unsigned long tl = this_load;
|
|
unsigned long tl_per_task;
|
|
unsigned long weight;
|
|
int balanced;
|
|
|
|
if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
|
|
return 0;
|
|
|
|
/*
|
|
* If sync wakeup then subtract the (maximum possible)
|
|
* effect of the currently running task from the load
|
|
* of the current CPU:
|
|
*/
|
|
if (sync) {
|
|
tg = task_group(current);
|
|
weight = current->se.load.weight;
|
|
|
|
tl += effective_load(tg, this_cpu, -weight, -weight);
|
|
load += effective_load(tg, prev_cpu, 0, -weight);
|
|
}
|
|
|
|
tg = task_group(p);
|
|
weight = p->se.load.weight;
|
|
|
|
balanced = 100*(tl + effective_load(tg, this_cpu, weight, weight)) <=
|
|
imbalance*(load + effective_load(tg, prev_cpu, 0, weight));
|
|
|
|
/*
|
|
* If the currently running task will sleep within
|
|
* a reasonable amount of time then attract this newly
|
|
* woken task:
|
|
*/
|
|
if (sync && balanced) {
|
|
if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
|
|
p->se.avg_overlap < sysctl_sched_migration_cost)
|
|
return 1;
|
|
}
|
|
|
|
schedstat_inc(p, se.nr_wakeups_affine_attempts);
|
|
tl_per_task = cpu_avg_load_per_task(this_cpu);
|
|
|
|
if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
|
|
balanced) {
|
|
/*
|
|
* This domain has SD_WAKE_AFFINE and
|
|
* p is cache cold in this domain, and
|
|
* there is no bad imbalance.
|
|
*/
|
|
schedstat_inc(this_sd, ttwu_move_affine);
|
|
schedstat_inc(p, se.nr_wakeups_affine);
|
|
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int select_task_rq_fair(struct task_struct *p, int sync)
|
|
{
|
|
struct sched_domain *sd, *this_sd = NULL;
|
|
int prev_cpu, this_cpu, new_cpu;
|
|
unsigned long load, this_load;
|
|
struct rq *rq, *this_rq;
|
|
unsigned int imbalance;
|
|
int idx;
|
|
|
|
prev_cpu = task_cpu(p);
|
|
rq = task_rq(p);
|
|
this_cpu = smp_processor_id();
|
|
this_rq = cpu_rq(this_cpu);
|
|
new_cpu = prev_cpu;
|
|
|
|
/*
|
|
* 'this_sd' is the first domain that both
|
|
* this_cpu and prev_cpu are present in:
|
|
*/
|
|
for_each_domain(this_cpu, sd) {
|
|
if (cpu_isset(prev_cpu, sd->span)) {
|
|
this_sd = sd;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
|
|
goto out;
|
|
|
|
/*
|
|
* Check for affine wakeup and passive balancing possibilities.
|
|
*/
|
|
if (!this_sd)
|
|
goto out;
|
|
|
|
idx = this_sd->wake_idx;
|
|
|
|
imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
|
|
|
|
load = source_load(prev_cpu, idx);
|
|
this_load = target_load(this_cpu, idx);
|
|
|
|
if (wake_affine(rq, this_sd, this_rq, p, prev_cpu, this_cpu, sync, idx,
|
|
load, this_load, imbalance))
|
|
return this_cpu;
|
|
|
|
if (prev_cpu == this_cpu)
|
|
goto out;
|
|
|
|
/*
|
|
* Start passive balancing when half the imbalance_pct
|
|
* limit is reached.
|
|
*/
|
|
if (this_sd->flags & SD_WAKE_BALANCE) {
|
|
if (imbalance*this_load <= 100*load) {
|
|
schedstat_inc(this_sd, ttwu_move_balance);
|
|
schedstat_inc(p, se.nr_wakeups_passive);
|
|
return this_cpu;
|
|
}
|
|
}
|
|
|
|
out:
|
|
return wake_idle(new_cpu, p);
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static unsigned long wakeup_gran(struct sched_entity *se)
|
|
{
|
|
unsigned long gran = sysctl_sched_wakeup_granularity;
|
|
|
|
/*
|
|
* More easily preempt - nice tasks, while not making it harder for
|
|
* + nice tasks.
|
|
*/
|
|
if (sched_feat(ASYM_GRAN))
|
|
gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se);
|
|
else
|
|
gran = calc_delta_fair(sysctl_sched_wakeup_granularity, se);
|
|
|
|
return gran;
|
|
}
|
|
|
|
/*
|
|
* Should 'se' preempt 'curr'.
|
|
*
|
|
* |s1
|
|
* |s2
|
|
* |s3
|
|
* g
|
|
* |<--->|c
|
|
*
|
|
* w(c, s1) = -1
|
|
* w(c, s2) = 0
|
|
* w(c, s3) = 1
|
|
*
|
|
*/
|
|
static int
|
|
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
|
|
{
|
|
s64 gran, vdiff = curr->vruntime - se->vruntime;
|
|
|
|
if (vdiff < 0)
|
|
return -1;
|
|
|
|
gran = wakeup_gran(curr);
|
|
if (vdiff > gran)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* return depth at which a sched entity is present in the hierarchy */
|
|
static inline int depth_se(struct sched_entity *se)
|
|
{
|
|
int depth = 0;
|
|
|
|
for_each_sched_entity(se)
|
|
depth++;
|
|
|
|
return depth;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
struct sched_entity *se = &curr->se, *pse = &p->se;
|
|
int se_depth, pse_depth;
|
|
|
|
if (unlikely(rt_prio(p->prio))) {
|
|
update_rq_clock(rq);
|
|
update_curr(cfs_rq);
|
|
resched_task(curr);
|
|
return;
|
|
}
|
|
|
|
if (unlikely(se == pse))
|
|
return;
|
|
|
|
cfs_rq_of(pse)->next = pse;
|
|
|
|
/*
|
|
* Batch tasks do not preempt (their preemption is driven by
|
|
* the tick):
|
|
*/
|
|
if (unlikely(p->policy == SCHED_BATCH))
|
|
return;
|
|
|
|
if (!sched_feat(WAKEUP_PREEMPT))
|
|
return;
|
|
|
|
/*
|
|
* preemption test can be made between sibling entities who are in the
|
|
* same cfs_rq i.e who have a common parent. Walk up the hierarchy of
|
|
* both tasks until we find their ancestors who are siblings of common
|
|
* parent.
|
|
*/
|
|
|
|
/* First walk up until both entities are at same depth */
|
|
se_depth = depth_se(se);
|
|
pse_depth = depth_se(pse);
|
|
|
|
while (se_depth > pse_depth) {
|
|
se_depth--;
|
|
se = parent_entity(se);
|
|
}
|
|
|
|
while (pse_depth > se_depth) {
|
|
pse_depth--;
|
|
pse = parent_entity(pse);
|
|
}
|
|
|
|
while (!is_same_group(se, pse)) {
|
|
se = parent_entity(se);
|
|
pse = parent_entity(pse);
|
|
}
|
|
|
|
if (wakeup_preempt_entity(se, pse) == 1)
|
|
resched_task(curr);
|
|
}
|
|
|
|
static struct task_struct *pick_next_task_fair(struct rq *rq)
|
|
{
|
|
struct task_struct *p;
|
|
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);
|
|
|
|
p = task_of(se);
|
|
hrtick_start_fair(rq, p);
|
|
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/**************************************************
|
|
* 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 struct task_struct *
|
|
__load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
|
|
{
|
|
struct task_struct *p = NULL;
|
|
struct sched_entity *se;
|
|
|
|
if (next == &cfs_rq->tasks)
|
|
return NULL;
|
|
|
|
/* Skip over entities that are not tasks */
|
|
do {
|
|
se = list_entry(next, struct sched_entity, group_node);
|
|
next = next->next;
|
|
} while (next != &cfs_rq->tasks && !entity_is_task(se));
|
|
|
|
if (next == &cfs_rq->tasks)
|
|
return NULL;
|
|
|
|
cfs_rq->balance_iterator = next;
|
|
|
|
if (entity_is_task(se))
|
|
p = task_of(se);
|
|
|
|
return p;
|
|
}
|
|
|
|
static struct task_struct *load_balance_start_fair(void *arg)
|
|
{
|
|
struct cfs_rq *cfs_rq = arg;
|
|
|
|
return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
|
|
}
|
|
|
|
static struct task_struct *load_balance_next_fair(void *arg)
|
|
{
|
|
struct cfs_rq *cfs_rq = arg;
|
|
|
|
return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
|
|
}
|
|
|
|
static unsigned long
|
|
__load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_load_move, struct sched_domain *sd,
|
|
enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
|
|
struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq_iterator cfs_rq_iterator;
|
|
|
|
cfs_rq_iterator.start = load_balance_start_fair;
|
|
cfs_rq_iterator.next = load_balance_next_fair;
|
|
cfs_rq_iterator.arg = cfs_rq;
|
|
|
|
return balance_tasks(this_rq, this_cpu, busiest,
|
|
max_load_move, sd, idle, all_pinned,
|
|
this_best_prio, &cfs_rq_iterator);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static unsigned long
|
|
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_load_move,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *all_pinned, int *this_best_prio)
|
|
{
|
|
long rem_load_move = max_load_move;
|
|
int busiest_cpu = cpu_of(busiest);
|
|
struct task_group *tg;
|
|
|
|
rcu_read_lock();
|
|
update_h_load(busiest_cpu);
|
|
|
|
list_for_each_entry(tg, &task_groups, list) {
|
|
struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu];
|
|
unsigned long busiest_h_load = busiest_cfs_rq->h_load;
|
|
unsigned long busiest_weight = busiest_cfs_rq->load.weight;
|
|
u64 rem_load, moved_load;
|
|
|
|
/*
|
|
* empty group
|
|
*/
|
|
if (!busiest_cfs_rq->task_weight)
|
|
continue;
|
|
|
|
rem_load = (u64)rem_load_move * busiest_weight;
|
|
rem_load = div_u64(rem_load, busiest_h_load + 1);
|
|
|
|
moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
|
|
rem_load, sd, idle, all_pinned, this_best_prio,
|
|
tg->cfs_rq[busiest_cpu]);
|
|
|
|
if (!moved_load)
|
|
continue;
|
|
|
|
moved_load *= busiest_h_load;
|
|
moved_load = div_u64(moved_load, busiest_weight + 1);
|
|
|
|
rem_load_move -= moved_load;
|
|
if (rem_load_move < 0)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return max_load_move - rem_load_move;
|
|
}
|
|
#else
|
|
static unsigned long
|
|
load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
unsigned long max_load_move,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *all_pinned, int *this_best_prio)
|
|
{
|
|
return __load_balance_fair(this_rq, this_cpu, busiest,
|
|
max_load_move, sd, idle, all_pinned,
|
|
this_best_prio, &busiest->cfs);
|
|
}
|
|
#endif
|
|
|
|
static int
|
|
move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
|
|
struct sched_domain *sd, enum cpu_idle_type idle)
|
|
{
|
|
struct cfs_rq *busy_cfs_rq;
|
|
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) {
|
|
/*
|
|
* pass busy_cfs_rq argument into
|
|
* load_balance_[start|next]_fair iterators
|
|
*/
|
|
cfs_rq_iterator.arg = busy_cfs_rq;
|
|
if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
|
|
&cfs_rq_iterator))
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* scheduler tick hitting a task of our scheduling class:
|
|
*/
|
|
static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
|
|
{
|
|
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, queued);
|
|
}
|
|
}
|
|
|
|
#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;
|
|
int this_cpu = smp_processor_id();
|
|
|
|
sched_info_queued(p);
|
|
|
|
update_curr(cfs_rq);
|
|
place_entity(cfs_rq, se, 1);
|
|
|
|
/* 'curr' will be NULL if the child belongs to a different group */
|
|
if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) &&
|
|
curr && 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);
|
|
}
|
|
|
|
enqueue_task_fair(rq, p, 0);
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
/*
|
|
* Priority of the task has changed. Check to see if we preempt
|
|
* the current task.
|
|
*/
|
|
static void prio_changed_fair(struct rq *rq, struct task_struct *p,
|
|
int oldprio, int running)
|
|
{
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (running) {
|
|
if (p->prio > oldprio)
|
|
resched_task(rq->curr);
|
|
} else
|
|
check_preempt_curr(rq, p);
|
|
}
|
|
|
|
/*
|
|
* We switched to the sched_fair class.
|
|
*/
|
|
static void switched_to_fair(struct rq *rq, struct task_struct *p,
|
|
int running)
|
|
{
|
|
/*
|
|
* We were most likely switched from sched_rt, so
|
|
* kick off the schedule if running, otherwise just see
|
|
* if we can still preempt the current task.
|
|
*/
|
|
if (running)
|
|
resched_task(rq->curr);
|
|
else
|
|
check_preempt_curr(rq, p);
|
|
}
|
|
|
|
/* 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);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static void moved_group_fair(struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
|
|
update_curr(cfs_rq);
|
|
place_entity(cfs_rq, &p->se, 1);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* All the scheduling class methods:
|
|
*/
|
|
static const struct sched_class fair_sched_class = {
|
|
.next = &idle_sched_class,
|
|
.enqueue_task = enqueue_task_fair,
|
|
.dequeue_task = dequeue_task_fair,
|
|
.yield_task = yield_task_fair,
|
|
#ifdef CONFIG_SMP
|
|
.select_task_rq = select_task_rq_fair,
|
|
#endif /* CONFIG_SMP */
|
|
|
|
.check_preempt_curr = check_preempt_wakeup,
|
|
|
|
.pick_next_task = pick_next_task_fair,
|
|
.put_prev_task = put_prev_task_fair,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.load_balance = load_balance_fair,
|
|
.move_one_task = move_one_task_fair,
|
|
#endif
|
|
|
|
.set_curr_task = set_curr_task_fair,
|
|
.task_tick = task_tick_fair,
|
|
.task_new = task_new_fair,
|
|
|
|
.prio_changed = prio_changed_fair,
|
|
.switched_to = switched_to_fair,
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
.moved_group = moved_group_fair,
|
|
#endif
|
|
};
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
static void print_cfs_stats(struct seq_file *m, int cpu)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
rcu_read_lock();
|
|
for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
|
|
print_cfs_rq(m, cpu, cfs_rq);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif
|