| /* |
| * Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH) |
| * |
| * Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| * |
| * Interactivity improvements by Mike Galbraith |
| * (C) 2007 Mike Galbraith <efault@gmx.de> |
| * |
| * Various enhancements by Dmitry Adamushko. |
| * (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com> |
| * |
| * Group scheduling enhancements by Srivatsa Vaddagiri |
| * Copyright IBM Corporation, 2007 |
| * Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> |
| * |
| * Scaled math optimizations by Thomas Gleixner |
| * Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de> |
| * |
| * Adaptive scheduling granularity, math enhancements by Peter Zijlstra |
| * Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
| */ |
| |
| #include <linux/latencytop.h> |
| |
| /* |
| * Targeted preemption latency for CPU-bound tasks: |
| * (default: 5ms * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * NOTE: this latency value is not the same as the concept of |
| * 'timeslice length' - timeslices in CFS are of variable length |
| * and have no persistent notion like in traditional, time-slice |
| * based scheduling concepts. |
| * |
| * (to see the precise effective timeslice length of your workload, |
| * run vmstat and monitor the context-switches (cs) field) |
| */ |
| unsigned int sysctl_sched_latency = 5000000ULL; |
| unsigned int normalized_sysctl_sched_latency = 5000000ULL; |
| |
| /* |
| * Minimal preemption granularity for CPU-bound tasks: |
| * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| */ |
| unsigned int sysctl_sched_min_granularity = 1000000ULL; |
| unsigned int normalized_sysctl_sched_min_granularity = 1000000ULL; |
| |
| /* |
| * is kept at sysctl_sched_latency / sysctl_sched_min_granularity |
| */ |
| static unsigned int sched_nr_latency = 5; |
| |
| /* |
| * After fork, child runs first. If set to 0 (default) then |
| * parent will (try to) run first. |
| */ |
| unsigned int sysctl_sched_child_runs_first __read_mostly; |
| |
| /* |
| * sys_sched_yield() compat mode |
| * |
| * This option switches the agressive yield implementation of the |
| * old scheduler back on. |
| */ |
| unsigned int __read_mostly sysctl_sched_compat_yield; |
| |
| /* |
| * SCHED_OTHER wake-up granularity. |
| * (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds) |
| * |
| * This option delays the preemption effects of decoupled workloads |
| * and reduces their over-scheduling. Synchronous workloads will still |
| * have immediate wakeup/sleep latencies. |
| */ |
| unsigned int sysctl_sched_wakeup_granularity = 1000000UL; |
| unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL; |
| |
| const_debug unsigned int sysctl_sched_migration_cost = 500000UL; |
| |
| static const struct sched_class fair_sched_class; |
| |
| /************************************************************** |
| * CFS operations on generic schedulable entities: |
| */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| /* cpu runqueue to which this cfs_rq is attached */ |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->rq; |
| } |
| |
| /* An entity is a task if it doesn't "own" a runqueue */ |
| #define entity_is_task(se) (!se->my_q) |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHED_DEBUG |
| WARN_ON_ONCE(!entity_is_task(se)); |
| #endif |
| return container_of(se, struct task_struct, se); |
| } |
| |
| /* Walk up scheduling entities hierarchy */ |
| #define for_each_sched_entity(se) \ |
| for (; se; se = se->parent) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return p->se.cfs_rq; |
| } |
| |
| /* runqueue on which this entity is (to be) queued */ |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| return se->cfs_rq; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return grp->my_q; |
| } |
| |
| /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on |
| * another cpu ('this_cpu') |
| */ |
| static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) |
| { |
| return cfs_rq->tg->cfs_rq[this_cpu]; |
| } |
| |
| /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) |
| |
| /* Do the two (enqueued) entities belong to the same group ? */ |
| static inline int |
| is_same_group(struct sched_entity *se, struct sched_entity *pse) |
| { |
| if (se->cfs_rq == pse->cfs_rq) |
| return 1; |
| |
| return 0; |
| } |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return se->parent; |
| } |
| |
| /* 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; |
| } |
| |
| static void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| int se_depth, pse_depth; |
| |
| /* |
| * 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); |
| } |
| } |
| |
| #else /* !CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| return container_of(se, struct task_struct, se); |
| } |
| |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return container_of(cfs_rq, struct rq, cfs); |
| } |
| |
| #define entity_is_task(se) 1 |
| |
| #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 sched_entity *se, struct sched_entity *pse) |
| { |
| return 1; |
| } |
| |
| static inline struct sched_entity *parent_entity(struct sched_entity *se) |
| { |
| return NULL; |
| } |
| |
| static inline void |
| find_matching_se(struct sched_entity **se, struct sched_entity **pse) |
| { |
| } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| |
| /************************************************************** |
| * Scheduling class tree data structure manipulation methods: |
| */ |
| |
| static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - min_vruntime); |
| if (delta > 0) |
| min_vruntime = vruntime; |
| |
| return min_vruntime; |
| } |
| |
| static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) |
| { |
| s64 delta = (s64)(vruntime - min_vruntime); |
| if (delta < 0) |
| min_vruntime = vruntime; |
| |
| return min_vruntime; |
| } |
| |
| static inline int entity_before(struct sched_entity *a, |
| struct sched_entity *b) |
| { |
| return (s64)(a->vruntime - b->vruntime) < 0; |
| } |
| |
| static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return se->vruntime - cfs_rq->min_vruntime; |
| } |
| |
| static void update_min_vruntime(struct cfs_rq *cfs_rq) |
| { |
| u64 vruntime = cfs_rq->min_vruntime; |
| |
| if (cfs_rq->curr) |
| vruntime = cfs_rq->curr->vruntime; |
| |
| if (cfs_rq->rb_leftmost) { |
| struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost, |
| struct sched_entity, |
| run_node); |
| |
| if (!cfs_rq->curr) |
| vruntime = se->vruntime; |
| else |
| vruntime = min_vruntime(vruntime, se->vruntime); |
| } |
| |
| cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); |
| } |
| |
| /* |
| * Enqueue an entity into the rb-tree: |
| */ |
| static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct rb_node **link = &cfs_rq->tasks_timeline.rb_node; |
| struct rb_node *parent = NULL; |
| struct sched_entity *entry; |
| s64 key = entity_key(cfs_rq, se); |
| int leftmost = 1; |
| |
| /* |
| * Find the right place in the rbtree: |
| */ |
| while (*link) { |
| parent = *link; |
| entry = rb_entry(parent, struct sched_entity, run_node); |
| /* |
| * We dont care about collisions. Nodes with |
| * the same key stay together. |
| */ |
| if (key < entity_key(cfs_rq, entry)) { |
| link = &parent->rb_left; |
| } else { |
| link = &parent->rb_right; |
| leftmost = 0; |
| } |
| } |
| |
| /* |
| * Maintain a cache of leftmost tree entries (it is frequently |
| * used): |
| */ |
| if (leftmost) |
| cfs_rq->rb_leftmost = &se->run_node; |
| |
| rb_link_node(&se->run_node, parent, link); |
| rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->rb_leftmost == &se->run_node) { |
| struct rb_node *next_node; |
| |
| next_node = rb_next(&se->run_node); |
| cfs_rq->rb_leftmost = next_node; |
| } |
| |
| rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
| } |
| |
| static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *left = cfs_rq->rb_leftmost; |
| |
| if (!left) |
| return NULL; |
| |
| return rb_entry(left, struct sched_entity, run_node); |
| } |
| |
| static struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) |
| { |
| struct rb_node *last = rb_last(&cfs_rq->tasks_timeline); |
| |
| if (!last) |
| return NULL; |
| |
| return rb_entry(last, struct sched_entity, run_node); |
| } |
| |
| /************************************************************** |
| * Scheduling class statistics methods: |
| */ |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| int sched_nr_latency_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, |
| loff_t *ppos) |
| { |
| int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| |
| if (ret || !write) |
| return ret; |
| |
| sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, |
| sysctl_sched_min_granularity); |
| |
| return 0; |
| } |
| #endif |
| |
| /* |
| * delta /= w |
| */ |
| static inline unsigned long |
| calc_delta_fair(unsigned long delta, struct sched_entity *se) |
| { |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load); |
| |
| return delta; |
| } |
| |
| /* |
| * The idea is to set a period in which each task runs once. |
| * |
| * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch |
| * this period because otherwise the slices get too small. |
| * |
| * p = (nr <= nl) ? l : l*nr/nl |
| */ |
| static u64 __sched_period(unsigned long nr_running) |
| { |
| u64 period = sysctl_sched_latency; |
| unsigned long nr_latency = sched_nr_latency; |
| |
| if (unlikely(nr_running > nr_latency)) { |
| period = sysctl_sched_min_granularity; |
| period *= nr_running; |
| } |
| |
| return period; |
| } |
| |
| /* |
| * We calculate the wall-time slice from the period by taking a part |
| * proportional to the weight. |
| * |
| * s = p*P[w/rw] |
| */ |
| static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq); |
| |
| for_each_sched_entity(se) { |
| struct load_weight *load; |
| struct load_weight lw; |
| |
| cfs_rq = cfs_rq_of(se); |
| load = &cfs_rq->load; |
| |
| if (unlikely(!se->on_rq)) { |
| lw = cfs_rq->load; |
| |
| update_load_add(&lw, se->load.weight); |
| load = &lw; |
| } |
| slice = calc_delta_mine(slice, se->load.weight, load); |
| } |
| return slice; |
| } |
| |
| /* |
| * We calculate the vruntime slice of a to be inserted task |
| * |
| * vs = s/w |
| */ |
| static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| return calc_delta_fair(sched_slice(cfs_rq, se), se); |
| } |
| |
| /* |
| * Update the current task's runtime statistics. Skip current tasks that |
| * are not in our scheduling class. |
| */ |
| static inline void |
| __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, |
| unsigned long delta_exec) |
| { |
| unsigned long delta_exec_weighted; |
| |
| schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max)); |
| |
| curr->sum_exec_runtime += delta_exec; |
| schedstat_add(cfs_rq, exec_clock, delta_exec); |
| delta_exec_weighted = calc_delta_fair(delta_exec, curr); |
| curr->vruntime += delta_exec_weighted; |
| update_min_vruntime(cfs_rq); |
| } |
| |
| static void update_curr(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq->curr; |
| u64 now = rq_of(cfs_rq)->clock; |
| unsigned long delta_exec; |
| |
| if (unlikely(!curr)) |
| return; |
| |
| /* |
| * Get the amount of time the current task was running |
| * since the last time we changed load (this cannot |
| * overflow on 32 bits): |
| */ |
| delta_exec = (unsigned long)(now - curr->exec_start); |
| if (!delta_exec) |
| return; |
| |
| __update_curr(cfs_rq, curr, delta_exec); |
| curr->exec_start = now; |
| |
| if (entity_is_task(curr)) { |
| struct task_struct *curtask = task_of(curr); |
| |
| trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); |
| cpuacct_charge(curtask, delta_exec); |
| account_group_exec_runtime(curtask, delta_exec); |
| } |
| } |
| |
| static inline void |
| update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| schedstat_set(se->wait_start, rq_of(cfs_rq)->clock); |
| } |
| |
| /* |
| * 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); |
| #ifdef CONFIG_SCHEDSTATS |
| if (entity_is_task(se)) { |
| trace_sched_stat_wait(task_of(se), |
| rq_of(cfs_rq)->clock - se->wait_start); |
| } |
| #endif |
| 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); |
| list_add(&se->group_node, &cfs_rq->tasks); |
| } |
| cfs_rq->nr_running++; |
| se->on_rq = 1; |
| } |
| |
| 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); |
| list_del_init(&se->group_node); |
| } |
| cfs_rq->nr_running--; |
| se->on_rq = 0; |
| } |
| |
| static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| #ifdef CONFIG_SCHEDSTATS |
| struct task_struct *tsk = NULL; |
| |
| if (entity_is_task(se)) |
| tsk = task_of(se); |
| |
| 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 (tsk) { |
| account_scheduler_latency(tsk, delta >> 10, 1); |
| trace_sched_stat_sleep(tsk, 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; |
| |
| if (tsk) { |
| if (tsk->in_iowait) { |
| se->iowait_sum += delta; |
| se->iowait_count++; |
| trace_sched_stat_iowait(tsk, 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 = 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(cfs_rq, se); |
| |
| /* sleeps up to a single latency don't count. */ |
| if (!initial && sched_feat(FAIR_SLEEPERS)) { |
| unsigned long thresh = sysctl_sched_latency; |
| |
| /* |
| * Convert the sleeper threshold into virtual time. |
| * SCHED_IDLE is a special sub-class. We care about |
| * fairness only relative to other SCHED_IDLE tasks, |
| * all of which have the same weight. |
| */ |
| if (sched_feat(NORMALIZED_SLEEPER) && (!entity_is_task(se) || |
| task_of(se)->policy != SCHED_IDLE)) |
| thresh = calc_delta_fair(thresh, se); |
| |
| /* |
| * Halve their sleep time's effect, to allow |
| * for a gentler effect of sleepers: |
| */ |
| if (sched_feat(GENTLE_FAIR_SLEEPERS)) |
| thresh >>= 1; |
| |
| 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 __clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (!se || cfs_rq->last == se) |
| cfs_rq->last = NULL; |
| |
| if (!se || cfs_rq->next == se) |
| cfs_rq->next = NULL; |
| } |
| |
| static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| for_each_sched_entity(se) |
| __clear_buddies(cfs_rq_of(se), 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 |
| } |
| |
| clear_buddies(cfs_rq, se); |
| |
| if (se != cfs_rq->curr) |
| __dequeue_entity(cfs_rq, se); |
| account_entity_dequeue(cfs_rq, se); |
| update_min_vruntime(cfs_rq); |
| } |
| |
| /* |
| * 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); |
| /* |
| * The current task ran long enough, ensure it doesn't get |
| * re-elected due to buddy favours. |
| */ |
| clear_buddies(cfs_rq, curr); |
| return; |
| } |
| |
| /* |
| * Ensure that a task that missed wakeup preemption by a |
| * narrow margin doesn't have to wait for a full slice. |
| * This also mitigates buddy induced latencies under load. |
| */ |
| if (!sched_feat(WAKEUP_PREEMPT)) |
| return; |
| |
| if (delta_exec < sysctl_sched_min_granularity) |
| return; |
| |
| if (cfs_rq->nr_running > 1) { |
| struct sched_entity *se = __pick_next_entity(cfs_rq); |
| s64 delta = curr->vruntime - se->vruntime; |
| |
| if (delta > 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 int |
| wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); |
| |
| static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *se = __pick_next_entity(cfs_rq); |
| struct sched_entity *left = se; |
| |
| if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) |
| se = cfs_rq->next; |
| |
| /* |
| * Prefer last buddy, try to return the CPU to a preempted task. |
| */ |
| if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) |
| se = cfs_rq->last; |
| |
| clear_buddies(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); |
| } |
| } |
| |
| /* |
| * called from enqueue/dequeue and updates the hrtick when the |
| * current task is from our class and nr_running is low enough |
| * to matter. |
| */ |
| static void hrtick_update(struct rq *rq) |
| { |
| struct task_struct *curr = rq->curr; |
| |
| if (curr->sched_class != &fair_sched_class) |
| return; |
| |
| if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency) |
| hrtick_start_fair(rq, curr); |
| } |
| #else /* !CONFIG_SCHED_HRTICK */ |
| static inline void |
| hrtick_start_fair(struct rq *rq, struct task_struct *p) |
| { |
| } |
| |
| static inline void hrtick_update(struct rq *rq) |
| { |
| } |
| #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_update(rq); |
| } |
| |
| /* |
| * 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_update(rq); |
| } |
| |
| /* |
| * 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; |
| |
| clear_buddies(cfs_rq, se); |
| |
| 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 || entity_before(rightmost, se))) |
| 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; |
| } |
| |
| #ifdef CONFIG_SMP |
| |
| #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]; |
| |
| 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; |
| |
| for_each_sched_entity(se) { |
| long S, rw, s, a, b; |
| long more_w; |
| |
| /* |
| * 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; |
| |
| 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); |
| |
| if (likely(b)) |
| wl /= 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; |
| } |
| |
| 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 sched_domain *sd, struct task_struct *p, int sync) |
| { |
| struct task_struct *curr = current; |
| unsigned long this_load, load; |
| int idx, this_cpu, prev_cpu; |
| unsigned long tl_per_task; |
| unsigned int imbalance; |
| struct task_group *tg; |
| unsigned long weight; |
| int balanced; |
| |
| idx = sd->wake_idx; |
| this_cpu = smp_processor_id(); |
| prev_cpu = task_cpu(p); |
| load = source_load(prev_cpu, idx); |
| this_load = target_load(this_cpu, idx); |
| |
| if (sync) { |
| if (sched_feat(SYNC_LESS) && |
| (curr->se.avg_overlap > sysctl_sched_migration_cost || |
| p->se.avg_overlap > sysctl_sched_migration_cost)) |
| sync = 0; |
| } else { |
| if (sched_feat(SYNC_MORE) && |
| (curr->se.avg_overlap < sysctl_sched_migration_cost && |
| p->se.avg_overlap < sysctl_sched_migration_cost)) |
| sync = 1; |
| } |
| |
| /* |
| * 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; |
| |
| this_load += effective_load(tg, this_cpu, -weight, -weight); |
| load += effective_load(tg, prev_cpu, 0, -weight); |
| } |
| |
| tg = task_group(p); |
| weight = p->se.load.weight; |
| |
| imbalance = 100 + (sd->imbalance_pct - 100) / 2; |
| |
| /* |
| * In low-load situations, where prev_cpu is idle and this_cpu is idle |
| * due to the sync cause above having dropped this_load to 0, we'll |
| * always have an imbalance, but there's really nothing you can do |
| * about that, so that's good too. |
| * |
| * Otherwise check if either cpus are near enough in load to allow this |
| * task to be woken on this_cpu. |
| */ |
| balanced = !this_load || |
| 100*(this_load + 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) |
| return 1; |
| |
| schedstat_inc(p, se.nr_wakeups_affine_attempts); |
| tl_per_task = cpu_avg_load_per_task(this_cpu); |
| |
| if (balanced || |
| (this_load <= load && |
| this_load + target_load(prev_cpu, idx) <= tl_per_task)) { |
| /* |
| * This domain has SD_WAKE_AFFINE and |
| * p is cache cold in this domain, and |
| * there is no bad imbalance. |
| */ |
| schedstat_inc(sd, ttwu_move_affine); |
| schedstat_inc(p, se.nr_wakeups_affine); |
| |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| * find_idlest_group finds and returns the least busy CPU group within the |
| * domain. |
| */ |
| static struct sched_group * |
| find_idlest_group(struct sched_domain *sd, struct task_struct *p, |
| int this_cpu, int load_idx) |
| { |
| struct sched_group *idlest = NULL, *this = NULL, *group = sd->groups; |
| unsigned long min_load = ULONG_MAX, this_load = 0; |
| int imbalance = 100 + (sd->imbalance_pct-100)/2; |
| |
| do { |
| unsigned long load, avg_load; |
| int local_group; |
| int i; |
| |
| /* Skip over this group if it has no CPUs allowed */ |
| if (!cpumask_intersects(sched_group_cpus(group), |
| &p->cpus_allowed)) |
| continue; |
| |
| local_group = cpumask_test_cpu(this_cpu, |
| sched_group_cpus(group)); |
| |
| /* Tally up the load of all CPUs in the group */ |
| avg_load = 0; |
| |
| for_each_cpu(i, sched_group_cpus(group)) { |
| /* Bias balancing toward cpus of our domain */ |
| if (local_group) |
| load = source_load(i, load_idx); |
| else |
| load = target_load(i, load_idx); |
| |
| avg_load += load; |
| } |
| |
| /* Adjust by relative CPU power of the group */ |
| avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power; |
| |
| if (local_group) { |
| this_load = avg_load; |
| this = group; |
| } else if (avg_load < min_load) { |
| min_load = avg_load; |
| idlest = group; |
| } |
| } while (group = group->next, group != sd->groups); |
| |
| if (!idlest || 100*this_load < imbalance*min_load) |
| return NULL; |
| return idlest; |
| } |
| |
| /* |
| * find_idlest_cpu - find the idlest cpu among the cpus in group. |
| */ |
| static int |
| find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) |
| { |
| unsigned long load, min_load = ULONG_MAX; |
| int idlest = -1; |
| int i; |
| |
| /* Traverse only the allowed CPUs */ |
| for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) { |
| load = weighted_cpuload(i); |
| |
| if (load < min_load || (load == min_load && i == this_cpu)) { |
| min_load = load; |
| idlest = i; |
| } |
| } |
| |
| return idlest; |
| } |
| |
| /* |
| * Try and locate an idle CPU in the sched_domain. |
| */ |
| static int |
| select_idle_sibling(struct task_struct *p, struct sched_domain *sd, int target) |
| { |
| int cpu = smp_processor_id(); |
| int prev_cpu = task_cpu(p); |
| int i; |
| |
| /* |
| * If this domain spans both cpu and prev_cpu (see the SD_WAKE_AFFINE |
| * test in select_task_rq_fair) and the prev_cpu is idle then that's |
| * always a better target than the current cpu. |
| */ |
| if (target == cpu && !cpu_rq(prev_cpu)->cfs.nr_running) |
| return prev_cpu; |
| |
| /* |
| * Otherwise, iterate the domain and find an elegible idle cpu. |
| */ |
| for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) { |
| if (!cpu_rq(i)->cfs.nr_running) { |
| target = i; |
| break; |
| } |
| } |
| |
| return target; |
| } |
| |
| /* |
| * sched_balance_self: balance the current task (running on cpu) in domains |
| * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and |
| * SD_BALANCE_EXEC. |
| * |
| * Balance, ie. select the least loaded group. |
| * |
| * Returns the target CPU number, or the same CPU if no balancing is needed. |
| * |
| * preempt must be disabled. |
| */ |
| static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) |
| { |
| struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; |
| int cpu = smp_processor_id(); |
| int prev_cpu = task_cpu(p); |
| int new_cpu = cpu; |
| int want_affine = 0; |
| int want_sd = 1; |
| int sync = wake_flags & WF_SYNC; |
| |
| if (sd_flag & SD_BALANCE_WAKE) { |
| if (sched_feat(AFFINE_WAKEUPS) && |
| cpumask_test_cpu(cpu, &p->cpus_allowed)) |
| want_affine = 1; |
| new_cpu = prev_cpu; |
| } |
| |
| for_each_domain(cpu, tmp) { |
| /* |
| * If power savings logic is enabled for a domain, see if we |
| * are not overloaded, if so, don't balance wider. |
| */ |
| if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) { |
| unsigned long power = 0; |
| unsigned long nr_running = 0; |
| unsigned long capacity; |
| int i; |
| |
| for_each_cpu(i, sched_domain_span(tmp)) { |
| power += power_of(i); |
| nr_running += cpu_rq(i)->cfs.nr_running; |
| } |
| |
| capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE); |
| |
| if (tmp->flags & SD_POWERSAVINGS_BALANCE) |
| nr_running /= 2; |
| |
| if (nr_running < capacity) |
| want_sd = 0; |
| } |
| |
| /* |
| * While iterating the domains looking for a spanning |
| * WAKE_AFFINE domain, adjust the affine target to any idle cpu |
| * in cache sharing domains along the way. |
| */ |
| if (want_affine) { |
| int target = -1; |
| |
| /* |
| * If both cpu and prev_cpu are part of this domain, |
| * cpu is a valid SD_WAKE_AFFINE target. |
| */ |
| if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) |
| target = cpu; |
| |
| /* |
| * If there's an idle sibling in this domain, make that |
| * the wake_affine target instead of the current cpu. |
| */ |
| if (tmp->flags & SD_PREFER_SIBLING) |
| target = select_idle_sibling(p, tmp, target); |
| |
| if (target >= 0) { |
| if (tmp->flags & SD_WAKE_AFFINE) { |
| affine_sd = tmp; |
| want_affine = 0; |
| } |
| cpu = target; |
| } |
| } |
| |
| if (!want_sd && !want_affine) |
| break; |
| |
| if (!(tmp->flags & sd_flag)) |
| continue; |
| |
| if (want_sd) |
| sd = tmp; |
| } |
| |
| if (sched_feat(LB_SHARES_UPDATE)) { |
| /* |
| * Pick the largest domain to update shares over |
| */ |
| tmp = sd; |
| if (affine_sd && (!tmp || |
| cpumask_weight(sched_domain_span(affine_sd)) > |
| cpumask_weight(sched_domain_span(sd)))) |
| tmp = affine_sd; |
| |
| if (tmp) |
| update_shares(tmp); |
| } |
| |
| if (affine_sd && wake_affine(affine_sd, p, sync)) |
| return cpu; |
| |
| while (sd) { |
| int load_idx = sd->forkexec_idx; |
| struct sched_group *group; |
| int weight; |
| |
| if (!(sd->flags & sd_flag)) { |
| sd = sd->child; |
| continue; |
| } |
| |
| if (sd_flag & SD_BALANCE_WAKE) |
| load_idx = sd->wake_idx; |
| |
| group = find_idlest_group(sd, p, cpu, load_idx); |
| if (!group) { |
| sd = sd->child; |
| continue; |
| } |
| |
| new_cpu = find_idlest_cpu(group, p, cpu); |
| if (new_cpu == -1 || new_cpu == cpu) { |
| /* Now try balancing at a lower domain level of cpu */ |
| sd = sd->child; |
| continue; |
| } |
| |
| /* Now try balancing at a lower domain level of new_cpu */ |
| cpu = new_cpu; |
| weight = cpumask_weight(sched_domain_span(sd)); |
| sd = NULL; |
| for_each_domain(cpu, tmp) { |
| if (weight <= cpumask_weight(sched_domain_span(tmp))) |
| break; |
| if (tmp->flags & sd_flag) |
| sd = tmp; |
| } |
| /* while loop will break here if sd == NULL */ |
| } |
| |
| return new_cpu; |
| } |
| #endif /* CONFIG_SMP */ |
| |
| /* |
| * Adaptive granularity |
| * |
| * se->avg_wakeup gives the average time a task runs until it does a wakeup, |
| * with the limit of wakeup_gran -- when it never does a wakeup. |
| * |
| * So the smaller avg_wakeup is the faster we want this task to preempt, |
| * but we don't want to treat the preemptee unfairly and therefore allow it |
| * to run for at least the amount of time we'd like to run. |
| * |
| * NOTE: we use 2*avg_wakeup to increase the probability of actually doing one |
| * |
| * NOTE: we use *nr_running to scale with load, this nicely matches the |
| * degrading latency on load. |
| */ |
| static unsigned long |
| adaptive_gran(struct sched_entity *curr, struct sched_entity *se) |
| { |
| u64 this_run = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; |
| u64 expected_wakeup = 2*se->avg_wakeup * cfs_rq_of(se)->nr_running; |
| u64 gran = 0; |
| |
| if (this_run < expected_wakeup) |
| gran = expected_wakeup - this_run; |
| |
| return min_t(s64, gran, sysctl_sched_wakeup_granularity); |
| } |
| |
| static unsigned long |
| wakeup_gran(struct sched_entity *curr, struct sched_entity *se) |
| { |
| unsigned long gran = sysctl_sched_wakeup_granularity; |
| |
| if (cfs_rq_of(curr)->curr && sched_feat(ADAPTIVE_GRAN)) |
| gran = adaptive_gran(curr, se); |
| |
| /* |
| * Since its curr running now, convert the gran from real-time |
| * to virtual-time in his units. |
| */ |
| if (sched_feat(ASYM_GRAN)) { |
| /* |
| * By using 'se' instead of 'curr' we penalize light tasks, so |
| * they get preempted easier. That is, if 'se' < 'curr' then |
| * the resulting gran will be larger, therefore penalizing the |
| * lighter, if otoh 'se' > 'curr' then the resulting gran will |
| * be smaller, again penalizing the lighter task. |
| * |
| * This is especially important for buddies when the leftmost |
| * task is higher priority than the buddy. |
| */ |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| gran = calc_delta_fair(gran, se); |
| } else { |
| if (unlikely(curr->load.weight != NICE_0_LOAD)) |
| gran = calc_delta_fair(gran, curr); |
| } |
| |
| 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, se); |
| if (vdiff > gran) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void set_last_buddy(struct sched_entity *se) |
| { |
| if (likely(task_of(se)->policy != SCHED_IDLE)) { |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->last = se; |
| } |
| } |
| |
| static void set_next_buddy(struct sched_entity *se) |
| { |
| if (likely(task_of(se)->policy != SCHED_IDLE)) { |
| for_each_sched_entity(se) |
| cfs_rq_of(se)->next = se; |
| } |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags) |
| { |
| struct task_struct *curr = rq->curr; |
| struct sched_entity *se = &curr->se, *pse = &p->se; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| int sync = wake_flags & WF_SYNC; |
| int scale = cfs_rq->nr_running >= sched_nr_latency; |
| |
| if (unlikely(rt_prio(p->prio))) |
| goto preempt; |
| |
| if (unlikely(p->sched_class != &fair_sched_class)) |
| return; |
| |
| if (unlikely(se == pse)) |
| return; |
| |
| if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) |
| set_next_buddy(pse); |
| |
| /* |
| * We can come here with TIF_NEED_RESCHED already set from new task |
| * wake up path. |
| */ |
| if (test_tsk_need_resched(curr)) |
| return; |
| |
| /* |
| * Batch and idle tasks do not preempt (their preemption is driven by |
| * the tick): |
| */ |
| if (unlikely(p->policy != SCHED_NORMAL)) |
| return; |
| |
| /* Idle tasks are by definition preempted by everybody. */ |
| if (unlikely(curr->policy == SCHED_IDLE)) |
| goto preempt; |
| |
| if (sched_feat(WAKEUP_SYNC) && sync) |
| goto preempt; |
| |
| if (sched_feat(WAKEUP_OVERLAP) && |
| se->avg_overlap < sysctl_sched_migration_cost && |
| pse->avg_overlap < sysctl_sched_migration_cost) |
| goto preempt; |
| |
| if (!sched_feat(WAKEUP_PREEMPT)) |
| return; |
| |
| update_curr(cfs_rq); |
| find_matching_se(&se, &pse); |
| BUG_ON(!pse); |
| if (wakeup_preempt_entity(se, pse) == 1) |
| goto preempt; |
| |
| return; |
| |
| preempt: |
| resched_task(curr); |
| /* |
| * Only set the backward buddy when the current task is still |
| * on the rq. This can happen when a wakeup gets interleaved |
| * with schedule on the ->pre_schedule() or idle_balance() |
| * point, either of which can * drop the rq lock. |
| * |
| * Also, during early boot the idle thread is in the fair class, |
| * for obvious reasons its a bad idea to schedule back to it. |
| */ |
| if (unlikely(!se->on_rq || curr == rq->idle)) |
| return; |
| |
| if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se)) |
| set_last_buddy(se); |
| } |
| |
| 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 (!cfs_rq->nr_running) |
| return NULL; |
| |
| do { |
| se = pick_next_entity(cfs_rq); |
| set_next_entity(cfs_rq, se); |
| 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; |
| |
| se = list_entry(next, struct sched_entity, group_node); |
| p = task_of(se); |
| cfs_rq->balance_iterator = next->next; |
| |
| 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_rcu(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; |
| } |
| |
| static void rq_online_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| } |
| |
| static void rq_offline_fair(struct rq *rq) |
| { |
| update_sysctl(); |
| } |
| |
| #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); |
| } |
| } |
| |
| /* |
| * called on fork with the child task as argument from the parent's context |
| * - child not yet on the tasklist |
| * - preemption disabled |
| */ |
| static void task_fork_fair(struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(current); |
| struct sched_entity *se = &p->se, *curr = cfs_rq->curr; |
| int this_cpu = smp_processor_id(); |
| struct rq *rq = this_rq(); |
| unsigned long flags; |
| |
| spin_lock_irqsave(&rq->lock, flags); |
| |
| if (unlikely(task_cpu(p) != this_cpu)) |
| __set_task_cpu(p, this_cpu); |
| |
| update_curr(cfs_rq); |
| |
| if (curr) |
| se->vruntime = curr->vruntime; |
| place_entity(cfs_rq, se, 1); |
| |
| if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) { |
| /* |
| * Upon rescheduling, sched_class::put_prev_task() will place |
| * 'current' within the tree based on its new key value. |
| */ |
| swap(curr->vruntime, se->vruntime); |
| resched_task(rq->curr); |
| } |
| |
| spin_unlock_irqrestore(&rq->lock, flags); |
| } |
| |
| /* |
| * 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, 0); |
| } |
| |
| /* |
| * 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, 0); |
| } |
| |
| /* 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 |
| |
| unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task) |
| { |
| struct sched_entity *se = &task->se; |
| unsigned int rr_interval = 0; |
| |
| /* |
| * Time slice is 0 for SCHED_OTHER tasks that are on an otherwise |
| * idle runqueue: |
| */ |
| if (rq->cfs.load.weight) |
| rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); |
| |
| return rr_interval; |
| } |
| |
| /* |
| * 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, |
| |
| .check_preempt_curr = check_preempt_wakeup, |
| |
| .pick_next_task = pick_next_task_fair, |
| .put_prev_task = put_prev_task_fair, |
| |
| #ifdef CONFIG_SMP |
| .select_task_rq = select_task_rq_fair, |
| |
| .load_balance = load_balance_fair, |
| .move_one_task = move_one_task_fair, |
| .rq_online = rq_online_fair, |
| .rq_offline = rq_offline_fair, |
| #endif |
| |
| .set_curr_task = set_curr_task_fair, |
| .task_tick = task_tick_fair, |
| .task_fork = task_fork_fair, |
| |
| .prio_changed = prio_changed_fair, |
| .switched_to = switched_to_fair, |
| |
| .get_rr_interval = get_rr_interval_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 |