| /* |
| * 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> |
| */ |
| |
| /* |
| * Targeted preemption latency for CPU-bound tasks: |
| * (default: 20ms, units: nanoseconds) |
| * |
| * NOTE: this latency value is not the same as the concept of |
| * 'timeslice length' - timeslices in CFS are of variable length. |
| * (to see the precise effective timeslice length of your workload, |
| * run vmstat and monitor the context-switches field) |
| * |
| * On SMP systems the value of this is multiplied by the log2 of the |
| * number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way |
| * systems, 4x on 8-way systems, 5x on 16-way systems, etc.) |
| * Targeted preemption latency for CPU-bound tasks: |
| */ |
| unsigned int sysctl_sched_latency __read_mostly = 20000000ULL; |
| |
| /* |
| * Minimal preemption granularity for CPU-bound tasks: |
| * (default: 2 msec, units: nanoseconds) |
| */ |
| unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL; |
| |
| /* |
| * SCHED_BATCH wake-up granularity. |
| * (default: 25 msec, 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_batch_wakeup_granularity __read_mostly = 25000000UL; |
| |
| /* |
| * SCHED_OTHER wake-up granularity. |
| * (default: 1 msec, 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 __read_mostly = 1000000UL; |
| |
| unsigned int sysctl_sched_stat_granularity __read_mostly; |
| |
| /* |
| * Initialized in sched_init_granularity() [to 5 times the base granularity]: |
| */ |
| unsigned int sysctl_sched_runtime_limit __read_mostly; |
| |
| /* |
| * Debugging: various feature bits |
| */ |
| enum { |
| SCHED_FEAT_FAIR_SLEEPERS = 1, |
| SCHED_FEAT_SLEEPER_AVG = 2, |
| SCHED_FEAT_SLEEPER_LOAD_AVG = 4, |
| SCHED_FEAT_PRECISE_CPU_LOAD = 8, |
| SCHED_FEAT_START_DEBIT = 16, |
| SCHED_FEAT_SKIP_INITIAL = 32, |
| }; |
| |
| unsigned int sysctl_sched_features __read_mostly = |
| SCHED_FEAT_FAIR_SLEEPERS *1 | |
| SCHED_FEAT_SLEEPER_AVG *0 | |
| SCHED_FEAT_SLEEPER_LOAD_AVG *1 | |
| SCHED_FEAT_PRECISE_CPU_LOAD *1 | |
| SCHED_FEAT_START_DEBIT *1 | |
| SCHED_FEAT_SKIP_INITIAL *0; |
| |
| extern 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; |
| } |
| |
| /* currently running entity (if any) on this cfs_rq */ |
| static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->curr; |
| } |
| |
| /* An entity is a task if it doesn't "own" a runqueue */ |
| #define entity_is_task(se) (!se->my_q) |
| |
| static inline void |
| set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| cfs_rq->curr = se; |
| } |
| |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct rq *rq_of(struct cfs_rq *cfs_rq) |
| { |
| return container_of(cfs_rq, struct rq, cfs); |
| } |
| |
| static inline struct sched_entity *cfs_rq_curr(struct cfs_rq *cfs_rq) |
| { |
| struct rq *rq = rq_of(cfs_rq); |
| |
| if (unlikely(rq->curr->sched_class != &fair_sched_class)) |
| return NULL; |
| |
| return &rq->curr->se; |
| } |
| |
| #define entity_is_task(se) 1 |
| |
| static inline void |
| set_cfs_rq_curr(struct cfs_rq *cfs_rq, struct sched_entity *se) { } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| static inline struct task_struct *task_of(struct sched_entity *se) |
| { |
| return container_of(se, struct task_struct, se); |
| } |
| |
| |
| /************************************************************** |
| * Scheduling class tree data structure manipulation methods: |
| */ |
| |
| /* |
| * Enqueue an entity into the rb-tree: |
| */ |
| static inline 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 = se->fair_key; |
| 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 - entry->fair_key < 0) { |
| 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); |
| update_load_add(&cfs_rq->load, se->load.weight); |
| cfs_rq->nr_running++; |
| se->on_rq = 1; |
| } |
| |
| static inline void |
| __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| if (cfs_rq->rb_leftmost == &se->run_node) |
| cfs_rq->rb_leftmost = rb_next(&se->run_node); |
| rb_erase(&se->run_node, &cfs_rq->tasks_timeline); |
| update_load_sub(&cfs_rq->load, se->load.weight); |
| cfs_rq->nr_running--; |
| se->on_rq = 0; |
| } |
| |
| static inline struct rb_node *first_fair(struct cfs_rq *cfs_rq) |
| { |
| return cfs_rq->rb_leftmost; |
| } |
| |
| static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| return rb_entry(first_fair(cfs_rq), struct sched_entity, run_node); |
| } |
| |
| /************************************************************** |
| * Scheduling class statistics methods: |
| */ |
| |
| /* |
| * Calculate the preemption granularity needed to schedule every |
| * runnable task once per sysctl_sched_latency amount of time. |
| * (down to a sensible low limit on granularity) |
| * |
| * For example, if there are 2 tasks running and latency is 10 msecs, |
| * we switch tasks every 5 msecs. If we have 3 tasks running, we have |
| * to switch tasks every 3.33 msecs to get a 10 msecs observed latency |
| * for each task. We do finer and finer scheduling up to until we |
| * reach the minimum granularity value. |
| * |
| * To achieve this we use the following dynamic-granularity rule: |
| * |
| * gran = lat/nr - lat/nr/nr |
| * |
| * This comes out of the following equations: |
| * |
| * kA1 + gran = kB1 |
| * kB2 + gran = kA2 |
| * kA2 = kA1 |
| * kB2 = kB1 - d + d/nr |
| * lat = d * nr |
| * |
| * Where 'k' is key, 'A' is task A (waiting), 'B' is task B (running), |
| * '1' is start of time, '2' is end of time, 'd' is delay between |
| * 1 and 2 (during which task B was running), 'nr' is number of tasks |
| * running, 'lat' is the the period of each task. ('lat' is the |
| * sched_latency that we aim for.) |
| */ |
| static long |
| sched_granularity(struct cfs_rq *cfs_rq) |
| { |
| unsigned int gran = sysctl_sched_latency; |
| unsigned int nr = cfs_rq->nr_running; |
| |
| if (nr > 1) { |
| gran = gran/nr - gran/nr/nr; |
| gran = max(gran, sysctl_sched_min_granularity); |
| } |
| |
| return gran; |
| } |
| |
| /* |
| * We rescale the rescheduling granularity of tasks according to their |
| * nice level, but only linearly, not exponentially: |
| */ |
| static long |
| niced_granularity(struct sched_entity *curr, unsigned long granularity) |
| { |
| u64 tmp; |
| |
| if (likely(curr->load.weight == NICE_0_LOAD)) |
| return granularity; |
| /* |
| * Positive nice levels get the same granularity as nice-0: |
| */ |
| if (likely(curr->load.weight < NICE_0_LOAD)) { |
| tmp = curr->load.weight * (u64)granularity; |
| return (long) (tmp >> NICE_0_SHIFT); |
| } |
| /* |
| * Negative nice level tasks get linearly finer |
| * granularity: |
| */ |
| tmp = curr->load.inv_weight * (u64)granularity; |
| |
| /* |
| * It will always fit into 'long': |
| */ |
| return (long) (tmp >> WMULT_SHIFT); |
| } |
| |
| static inline void |
| limit_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| long limit = sysctl_sched_runtime_limit; |
| |
| /* |
| * Niced tasks have the same history dynamic range as |
| * non-niced tasks: |
| */ |
| if (unlikely(se->wait_runtime > limit)) { |
| se->wait_runtime = limit; |
| schedstat_inc(se, wait_runtime_overruns); |
| schedstat_inc(cfs_rq, wait_runtime_overruns); |
| } |
| if (unlikely(se->wait_runtime < -limit)) { |
| se->wait_runtime = -limit; |
| schedstat_inc(se, wait_runtime_underruns); |
| schedstat_inc(cfs_rq, wait_runtime_underruns); |
| } |
| } |
| |
| static inline void |
| __add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta) |
| { |
| se->wait_runtime += delta; |
| schedstat_add(se, sum_wait_runtime, delta); |
| limit_wait_runtime(cfs_rq, se); |
| } |
| |
| static void |
| add_wait_runtime(struct cfs_rq *cfs_rq, struct sched_entity *se, long delta) |
| { |
| schedstat_add(cfs_rq, wait_runtime, -se->wait_runtime); |
| __add_wait_runtime(cfs_rq, se, delta); |
| schedstat_add(cfs_rq, wait_runtime, se->wait_runtime); |
| } |
| |
| /* |
| * 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, delta_exec, delta_fair, delta_mine; |
| struct load_weight *lw = &cfs_rq->load; |
| unsigned long load = lw->weight; |
| |
| delta_exec = curr->delta_exec; |
| schedstat_set(curr->exec_max, max((u64)delta_exec, curr->exec_max)); |
| |
| curr->sum_exec_runtime += delta_exec; |
| cfs_rq->exec_clock += delta_exec; |
| |
| if (unlikely(!load)) |
| return; |
| |
| delta_fair = calc_delta_fair(delta_exec, lw); |
| delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw); |
| |
| if (cfs_rq->sleeper_bonus > sysctl_sched_latency) { |
| delta = min((u64)delta_mine, cfs_rq->sleeper_bonus); |
| delta = min(delta, (unsigned long)( |
| (long)sysctl_sched_runtime_limit - curr->wait_runtime)); |
| cfs_rq->sleeper_bonus -= delta; |
| delta_mine -= delta; |
| } |
| |
| cfs_rq->fair_clock += delta_fair; |
| /* |
| * We executed delta_exec amount of time on the CPU, |
| * but we were only entitled to delta_mine amount of |
| * time during that period (if nr_running == 1 then |
| * the two values are equal) |
| * [Note: delta_mine - delta_exec is negative]: |
| */ |
| add_wait_runtime(cfs_rq, curr, delta_mine - delta_exec); |
| } |
| |
| static void update_curr(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr = cfs_rq_curr(cfs_rq); |
| 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)(rq_of(cfs_rq)->clock - curr->exec_start); |
| |
| curr->delta_exec += delta_exec; |
| |
| if (unlikely(curr->delta_exec > sysctl_sched_stat_granularity)) { |
| __update_curr(cfs_rq, curr); |
| curr->delta_exec = 0; |
| } |
| curr->exec_start = rq_of(cfs_rq)->clock; |
| } |
| |
| static inline void |
| update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| se->wait_start_fair = cfs_rq->fair_clock; |
| schedstat_set(se->wait_start, rq_of(cfs_rq)->clock); |
| } |
| |
| /* |
| * We calculate fair deltas here, so protect against the random effects |
| * of a multiplication overflow by capping it to the runtime limit: |
| */ |
| #if BITS_PER_LONG == 32 |
| static inline unsigned long |
| calc_weighted(unsigned long delta, unsigned long weight, int shift) |
| { |
| u64 tmp = (u64)delta * weight >> shift; |
| |
| if (unlikely(tmp > sysctl_sched_runtime_limit*2)) |
| return sysctl_sched_runtime_limit*2; |
| return tmp; |
| } |
| #else |
| static inline unsigned long |
| calc_weighted(unsigned long delta, unsigned long weight, int shift) |
| { |
| return delta * weight >> shift; |
| } |
| #endif |
| |
| /* |
| * Task is being enqueued - update stats: |
| */ |
| static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| s64 key; |
| |
| /* |
| * Are we enqueueing a waiting task? (for current tasks |
| * a dequeue/enqueue event is a NOP) |
| */ |
| if (se != cfs_rq_curr(cfs_rq)) |
| update_stats_wait_start(cfs_rq, se); |
| /* |
| * Update the key: |
| */ |
| key = cfs_rq->fair_clock; |
| |
| /* |
| * Optimize the common nice 0 case: |
| */ |
| if (likely(se->load.weight == NICE_0_LOAD)) { |
| key -= se->wait_runtime; |
| } else { |
| u64 tmp; |
| |
| if (se->wait_runtime < 0) { |
| tmp = -se->wait_runtime; |
| key += (tmp * se->load.inv_weight) >> |
| (WMULT_SHIFT - NICE_0_SHIFT); |
| } else { |
| tmp = se->wait_runtime; |
| key -= (tmp * se->load.inv_weight) >> |
| (WMULT_SHIFT - NICE_0_SHIFT); |
| } |
| } |
| |
| se->fair_key = key; |
| } |
| |
| /* |
| * Note: must be called with a freshly updated rq->fair_clock. |
| */ |
| static inline void |
| __update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| unsigned long delta_fair = se->delta_fair_run; |
| |
| schedstat_set(se->wait_max, max(se->wait_max, |
| rq_of(cfs_rq)->clock - se->wait_start)); |
| |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| delta_fair = calc_weighted(delta_fair, se->load.weight, |
| NICE_0_SHIFT); |
| |
| add_wait_runtime(cfs_rq, se, delta_fair); |
| } |
| |
| static void |
| update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| unsigned long delta_fair; |
| |
| delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit), |
| (u64)(cfs_rq->fair_clock - se->wait_start_fair)); |
| |
| se->delta_fair_run += delta_fair; |
| if (unlikely(abs(se->delta_fair_run) >= |
| sysctl_sched_stat_granularity)) { |
| __update_stats_wait_end(cfs_rq, se); |
| se->delta_fair_run = 0; |
| } |
| |
| se->wait_start_fair = 0; |
| schedstat_set(se->wait_start, 0); |
| } |
| |
| static inline void |
| update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| update_curr(cfs_rq); |
| /* |
| * Mark the end of the wait period if dequeueing a |
| * waiting task: |
| */ |
| if (se != cfs_rq_curr(cfs_rq)) |
| update_stats_wait_end(cfs_rq, se); |
| } |
| |
| /* |
| * We are picking a new current task - update its stats: |
| */ |
| static inline void |
| update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * We are starting a new run period: |
| */ |
| se->exec_start = rq_of(cfs_rq)->clock; |
| } |
| |
| /* |
| * We are descheduling a task - update its stats: |
| */ |
| static inline void |
| update_stats_curr_end(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| se->exec_start = 0; |
| } |
| |
| /************************************************** |
| * Scheduling class queueing methods: |
| */ |
| |
| static void __enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| unsigned long load = cfs_rq->load.weight, delta_fair; |
| long prev_runtime; |
| |
| /* |
| * Do not boost sleepers if there's too much bonus 'in flight' |
| * already: |
| */ |
| if (unlikely(cfs_rq->sleeper_bonus > sysctl_sched_runtime_limit)) |
| return; |
| |
| if (sysctl_sched_features & SCHED_FEAT_SLEEPER_LOAD_AVG) |
| load = rq_of(cfs_rq)->cpu_load[2]; |
| |
| delta_fair = se->delta_fair_sleep; |
| |
| /* |
| * Fix up delta_fair with the effect of us running |
| * during the whole sleep period: |
| */ |
| if (sysctl_sched_features & SCHED_FEAT_SLEEPER_AVG) |
| delta_fair = div64_likely32((u64)delta_fair * load, |
| load + se->load.weight); |
| |
| if (unlikely(se->load.weight != NICE_0_LOAD)) |
| delta_fair = calc_weighted(delta_fair, se->load.weight, |
| NICE_0_SHIFT); |
| |
| prev_runtime = se->wait_runtime; |
| __add_wait_runtime(cfs_rq, se, delta_fair); |
| schedstat_add(cfs_rq, wait_runtime, se->wait_runtime); |
| delta_fair = se->wait_runtime - prev_runtime; |
| |
| /* |
| * Track the amount of bonus we've given to sleepers: |
| */ |
| cfs_rq->sleeper_bonus += delta_fair; |
| } |
| |
| static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| struct task_struct *tsk = task_of(se); |
| unsigned long delta_fair; |
| |
| if ((entity_is_task(se) && tsk->policy == SCHED_BATCH) || |
| !(sysctl_sched_features & SCHED_FEAT_FAIR_SLEEPERS)) |
| return; |
| |
| delta_fair = (unsigned long)min((u64)(2*sysctl_sched_runtime_limit), |
| (u64)(cfs_rq->fair_clock - se->sleep_start_fair)); |
| |
| se->delta_fair_sleep += delta_fair; |
| if (unlikely(abs(se->delta_fair_sleep) >= |
| sysctl_sched_stat_granularity)) { |
| __enqueue_sleeper(cfs_rq, se); |
| se->delta_fair_sleep = 0; |
| } |
| |
| se->sleep_start_fair = 0; |
| |
| #ifdef CONFIG_SCHEDSTATS |
| if (se->sleep_start) { |
| u64 delta = rq_of(cfs_rq)->clock - se->sleep_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->sleep_max)) |
| se->sleep_max = delta; |
| |
| se->sleep_start = 0; |
| se->sum_sleep_runtime += delta; |
| } |
| if (se->block_start) { |
| u64 delta = rq_of(cfs_rq)->clock - se->block_start; |
| |
| if ((s64)delta < 0) |
| delta = 0; |
| |
| if (unlikely(delta > se->block_max)) |
| se->block_max = delta; |
| |
| se->block_start = 0; |
| se->sum_sleep_runtime += delta; |
| } |
| #endif |
| } |
| |
| static void |
| enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup) |
| { |
| /* |
| * Update the fair clock. |
| */ |
| update_curr(cfs_rq); |
| |
| if (wakeup) |
| enqueue_sleeper(cfs_rq, se); |
| |
| update_stats_enqueue(cfs_rq, se); |
| __enqueue_entity(cfs_rq, se); |
| } |
| |
| static void |
| dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) |
| { |
| update_stats_dequeue(cfs_rq, se); |
| if (sleep) { |
| se->sleep_start_fair = cfs_rq->fair_clock; |
| #ifdef CONFIG_SCHEDSTATS |
| if (entity_is_task(se)) { |
| struct task_struct *tsk = task_of(se); |
| |
| if (tsk->state & TASK_INTERRUPTIBLE) |
| se->sleep_start = rq_of(cfs_rq)->clock; |
| if (tsk->state & TASK_UNINTERRUPTIBLE) |
| se->block_start = rq_of(cfs_rq)->clock; |
| } |
| cfs_rq->wait_runtime -= se->wait_runtime; |
| #endif |
| } |
| __dequeue_entity(cfs_rq, se); |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void |
| __check_preempt_curr_fair(struct cfs_rq *cfs_rq, struct sched_entity *se, |
| struct sched_entity *curr, unsigned long granularity) |
| { |
| s64 __delta = curr->fair_key - se->fair_key; |
| |
| /* |
| * Take scheduling granularity into account - do not |
| * preempt the current task unless the best task has |
| * a larger than sched_granularity fairness advantage: |
| */ |
| if (__delta > niced_granularity(curr, granularity)) |
| resched_task(rq_of(cfs_rq)->curr); |
| } |
| |
| static inline void |
| set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| /* |
| * Any task has to be enqueued before it get to execute on |
| * a CPU. So account for the time it spent waiting on the |
| * runqueue. (note, here we rely on pick_next_task() having |
| * done a put_prev_task_fair() shortly before this, which |
| * updated rq->fair_clock - used by update_stats_wait_end()) |
| */ |
| update_stats_wait_end(cfs_rq, se); |
| update_stats_curr_start(cfs_rq, se); |
| set_cfs_rq_curr(cfs_rq, se); |
| } |
| |
| static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *se = __pick_next_entity(cfs_rq); |
| |
| set_next_entity(cfs_rq, se); |
| |
| return se; |
| } |
| |
| static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) |
| { |
| /* |
| * If still on the runqueue then deactivate_task() |
| * was not called and update_curr() has to be done: |
| */ |
| if (prev->on_rq) |
| update_curr(cfs_rq); |
| |
| update_stats_curr_end(cfs_rq, prev); |
| |
| if (prev->on_rq) |
| update_stats_wait_start(cfs_rq, prev); |
| set_cfs_rq_curr(cfs_rq, NULL); |
| } |
| |
| static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| { |
| struct sched_entity *next; |
| |
| /* |
| * Dequeue and enqueue the task to update its |
| * position within the tree: |
| */ |
| dequeue_entity(cfs_rq, curr, 0); |
| enqueue_entity(cfs_rq, curr, 0); |
| |
| /* |
| * Reschedule if another task tops the current one. |
| */ |
| next = __pick_next_entity(cfs_rq); |
| if (next == curr) |
| return; |
| |
| __check_preempt_curr_fair(cfs_rq, next, curr, |
| sched_granularity(cfs_rq)); |
| } |
| |
| /************************************************** |
| * CFS operations on tasks: |
| */ |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| |
| /* Walk up scheduling entities hierarchy */ |
| #define for_each_sched_entity(se) \ |
| for (; se; se = se->parent) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return p->se.cfs_rq; |
| } |
| |
| /* runqueue on which this entity is (to be) queued */ |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| return se->cfs_rq; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return grp->my_q; |
| } |
| |
| /* Given a group's cfs_rq on one cpu, return its corresponding cfs_rq on |
| * another cpu ('this_cpu') |
| */ |
| static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) |
| { |
| /* A later patch will take group into account */ |
| return &cpu_rq(this_cpu)->cfs; |
| } |
| |
| /* Iterate thr' all leaf cfs_rq's on a runqueue */ |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| list_for_each_entry(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) |
| |
| /* Do the two (enqueued) tasks belong to the same group ? */ |
| static inline int is_same_group(struct task_struct *curr, struct task_struct *p) |
| { |
| if (curr->se.cfs_rq == p->se.cfs_rq) |
| return 1; |
| |
| return 0; |
| } |
| |
| #else /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| #define for_each_sched_entity(se) \ |
| for (; se; se = NULL) |
| |
| static inline struct cfs_rq *task_cfs_rq(struct task_struct *p) |
| { |
| return &task_rq(p)->cfs; |
| } |
| |
| static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se) |
| { |
| struct task_struct *p = task_of(se); |
| struct rq *rq = task_rq(p); |
| |
| return &rq->cfs; |
| } |
| |
| /* runqueue "owned" by this group */ |
| static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) |
| { |
| return NULL; |
| } |
| |
| static inline struct cfs_rq *cpu_cfs_rq(struct cfs_rq *cfs_rq, int this_cpu) |
| { |
| return &cpu_rq(this_cpu)->cfs; |
| } |
| |
| #define for_each_leaf_cfs_rq(rq, cfs_rq) \ |
| for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) |
| |
| static inline int is_same_group(struct task_struct *curr, struct task_struct *p) |
| { |
| return 1; |
| } |
| |
| #endif /* CONFIG_FAIR_GROUP_SCHED */ |
| |
| /* |
| * The enqueue_task method is called before nr_running is |
| * increased. Here we update the fair scheduling stats and |
| * then put the task into the rbtree: |
| */ |
| static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| |
| for_each_sched_entity(se) { |
| if (se->on_rq) |
| break; |
| cfs_rq = cfs_rq_of(se); |
| enqueue_entity(cfs_rq, se, wakeup); |
| } |
| } |
| |
| /* |
| * The dequeue_task method is called before nr_running is |
| * decreased. We remove the task from the rbtree and |
| * update the fair scheduling stats: |
| */ |
| static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &p->se; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| dequeue_entity(cfs_rq, se, sleep); |
| /* Don't dequeue parent if it has other entities besides us */ |
| if (cfs_rq->load.weight) |
| break; |
| } |
| } |
| |
| /* |
| * sched_yield() support is very simple - we dequeue and enqueue |
| */ |
| static void yield_task_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(p); |
| |
| __update_rq_clock(rq); |
| /* |
| * Dequeue and enqueue the task to update its |
| * position within the tree: |
| */ |
| dequeue_entity(cfs_rq, &p->se, 0); |
| enqueue_entity(cfs_rq, &p->se, 0); |
| } |
| |
| /* |
| * Preempt the current task with a newly woken task if needed: |
| */ |
| static void check_preempt_curr_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct task_struct *curr = rq->curr; |
| struct cfs_rq *cfs_rq = task_cfs_rq(curr); |
| unsigned long gran; |
| |
| if (unlikely(rt_prio(p->prio))) { |
| update_rq_clock(rq); |
| update_curr(cfs_rq); |
| resched_task(curr); |
| return; |
| } |
| |
| gran = sysctl_sched_wakeup_granularity; |
| /* |
| * Batch tasks prefer throughput over latency: |
| */ |
| if (unlikely(p->policy == SCHED_BATCH)) |
| gran = sysctl_sched_batch_wakeup_granularity; |
| |
| if (is_same_group(curr, p)) |
| __check_preempt_curr_fair(cfs_rq, &p->se, &curr->se, gran); |
| } |
| |
| static struct task_struct *pick_next_task_fair(struct rq *rq) |
| { |
| struct cfs_rq *cfs_rq = &rq->cfs; |
| struct sched_entity *se; |
| |
| if (unlikely(!cfs_rq->nr_running)) |
| return NULL; |
| |
| do { |
| se = pick_next_entity(cfs_rq); |
| cfs_rq = group_cfs_rq(se); |
| } while (cfs_rq); |
| |
| return task_of(se); |
| } |
| |
| /* |
| * Account for a descheduled task: |
| */ |
| static void put_prev_task_fair(struct rq *rq, struct task_struct *prev) |
| { |
| struct sched_entity *se = &prev->se; |
| struct cfs_rq *cfs_rq; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| put_prev_entity(cfs_rq, se); |
| } |
| } |
| |
| /************************************************** |
| * Fair scheduling class load-balancing methods: |
| */ |
| |
| /* |
| * Load-balancing iterator. Note: while the runqueue stays locked |
| * during the whole iteration, the current task might be |
| * dequeued so the iterator has to be dequeue-safe. Here we |
| * achieve that by always pre-iterating before returning |
| * the current task: |
| */ |
| static inline struct task_struct * |
| __load_balance_iterator(struct cfs_rq *cfs_rq, struct rb_node *curr) |
| { |
| struct task_struct *p; |
| |
| if (!curr) |
| return NULL; |
| |
| p = rb_entry(curr, struct task_struct, se.run_node); |
| cfs_rq->rb_load_balance_curr = rb_next(curr); |
| |
| return p; |
| } |
| |
| static struct task_struct *load_balance_start_fair(void *arg) |
| { |
| struct cfs_rq *cfs_rq = arg; |
| |
| return __load_balance_iterator(cfs_rq, first_fair(cfs_rq)); |
| } |
| |
| static struct task_struct *load_balance_next_fair(void *arg) |
| { |
| struct cfs_rq *cfs_rq = arg; |
| |
| return __load_balance_iterator(cfs_rq, cfs_rq->rb_load_balance_curr); |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| static int cfs_rq_best_prio(struct cfs_rq *cfs_rq) |
| { |
| struct sched_entity *curr; |
| struct task_struct *p; |
| |
| if (!cfs_rq->nr_running) |
| return MAX_PRIO; |
| |
| curr = __pick_next_entity(cfs_rq); |
| p = task_of(curr); |
| |
| return p->prio; |
| } |
| #endif |
| |
| static unsigned long |
| load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, |
| unsigned long max_nr_move, unsigned long max_load_move, |
| struct sched_domain *sd, enum cpu_idle_type idle, |
| int *all_pinned, int *this_best_prio) |
| { |
| struct cfs_rq *busy_cfs_rq; |
| unsigned long load_moved, total_nr_moved = 0, nr_moved; |
| long rem_load_move = max_load_move; |
| struct rq_iterator cfs_rq_iterator; |
| |
| cfs_rq_iterator.start = load_balance_start_fair; |
| cfs_rq_iterator.next = load_balance_next_fair; |
| |
| for_each_leaf_cfs_rq(busiest, busy_cfs_rq) { |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| struct cfs_rq *this_cfs_rq; |
| long imbalance; |
| unsigned long maxload; |
| |
| this_cfs_rq = cpu_cfs_rq(busy_cfs_rq, this_cpu); |
| |
| imbalance = busy_cfs_rq->load.weight - this_cfs_rq->load.weight; |
| /* Don't pull if this_cfs_rq has more load than busy_cfs_rq */ |
| if (imbalance <= 0) |
| continue; |
| |
| /* Don't pull more than imbalance/2 */ |
| imbalance /= 2; |
| maxload = min(rem_load_move, imbalance); |
| |
| *this_best_prio = cfs_rq_best_prio(this_cfs_rq); |
| #else |
| # define maxload rem_load_move |
| #endif |
| /* pass busy_cfs_rq argument into |
| * load_balance_[start|next]_fair iterators |
| */ |
| cfs_rq_iterator.arg = busy_cfs_rq; |
| nr_moved = balance_tasks(this_rq, this_cpu, busiest, |
| max_nr_move, maxload, sd, idle, all_pinned, |
| &load_moved, this_best_prio, &cfs_rq_iterator); |
| |
| total_nr_moved += nr_moved; |
| max_nr_move -= nr_moved; |
| rem_load_move -= load_moved; |
| |
| if (max_nr_move <= 0 || rem_load_move <= 0) |
| break; |
| } |
| |
| return max_load_move - rem_load_move; |
| } |
| |
| /* |
| * scheduler tick hitting a task of our scheduling class: |
| */ |
| static void task_tick_fair(struct rq *rq, struct task_struct *curr) |
| { |
| struct cfs_rq *cfs_rq; |
| struct sched_entity *se = &curr->se; |
| |
| for_each_sched_entity(se) { |
| cfs_rq = cfs_rq_of(se); |
| entity_tick(cfs_rq, se); |
| } |
| } |
| |
| /* |
| * Share the fairness runtime between parent and child, thus the |
| * total amount of pressure for CPU stays equal - new tasks |
| * get a chance to run but frequent forkers are not allowed to |
| * monopolize the CPU. Note: the parent runqueue is locked, |
| * the child is not running yet. |
| */ |
| static void task_new_fair(struct rq *rq, struct task_struct *p) |
| { |
| struct cfs_rq *cfs_rq = task_cfs_rq(p); |
| struct sched_entity *se = &p->se; |
| |
| sched_info_queued(p); |
| |
| update_stats_enqueue(cfs_rq, se); |
| /* |
| * Child runs first: we let it run before the parent |
| * until it reschedules once. We set up the key so that |
| * it will preempt the parent: |
| */ |
| p->se.fair_key = current->se.fair_key - |
| niced_granularity(&rq->curr->se, sched_granularity(cfs_rq)) - 1; |
| /* |
| * The first wait is dominated by the child-runs-first logic, |
| * so do not credit it with that waiting time yet: |
| */ |
| if (sysctl_sched_features & SCHED_FEAT_SKIP_INITIAL) |
| p->se.wait_start_fair = 0; |
| |
| /* |
| * The statistical average of wait_runtime is about |
| * -granularity/2, so initialize the task with that: |
| */ |
| if (sysctl_sched_features & SCHED_FEAT_START_DEBIT) |
| p->se.wait_runtime = -(sched_granularity(cfs_rq) / 2); |
| |
| __enqueue_entity(cfs_rq, se); |
| } |
| |
| #ifdef CONFIG_FAIR_GROUP_SCHED |
| /* Account for a task changing its policy or group. |
| * |
| * This routine is mostly called to set cfs_rq->curr field when a task |
| * migrates between groups/classes. |
| */ |
| static void set_curr_task_fair(struct rq *rq) |
| { |
| struct sched_entity *se = &rq->curr->se; |
| |
| for_each_sched_entity(se) |
| set_next_entity(cfs_rq_of(se), se); |
| } |
| #else |
| static void set_curr_task_fair(struct rq *rq) |
| { |
| } |
| #endif |
| |
| /* |
| * All the scheduling class methods: |
| */ |
| struct sched_class fair_sched_class __read_mostly = { |
| .enqueue_task = enqueue_task_fair, |
| .dequeue_task = dequeue_task_fair, |
| .yield_task = yield_task_fair, |
| |
| .check_preempt_curr = check_preempt_curr_fair, |
| |
| .pick_next_task = pick_next_task_fair, |
| .put_prev_task = put_prev_task_fair, |
| |
| .load_balance = load_balance_fair, |
| |
| .set_curr_task = set_curr_task_fair, |
| .task_tick = task_tick_fair, |
| .task_new = task_new_fair, |
| }; |
| |
| #ifdef CONFIG_SCHED_DEBUG |
| static void print_cfs_stats(struct seq_file *m, int cpu) |
| { |
| struct cfs_rq *cfs_rq; |
| |
| for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) |
| print_cfs_rq(m, cpu, cfs_rq); |
| } |
| #endif |