diff options
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 879 |
1 files changed, 771 insertions, 108 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 433491c2dc8..5c9e67923b7 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -89,6 +89,20 @@ const_debug unsigned int sysctl_sched_migration_cost = 500000UL; */ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; +#ifdef CONFIG_CFS_BANDWIDTH +/* + * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool + * each time a cfs_rq requests quota. + * + * Note: in the case that the slice exceeds the runtime remaining (either due + * to consumption or the quota being specified to be smaller than the slice) + * we will always only issue the remaining available time. + * + * default: 5 msec, units: microseconds + */ +unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; +#endif + static const struct sched_class fair_sched_class; /************************************************************** @@ -135,14 +149,6 @@ 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]; -} - static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) { if (!cfs_rq->on_list) { @@ -271,11 +277,6 @@ 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; -} - static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) { } @@ -305,6 +306,8 @@ find_matching_se(struct sched_entity **se, struct sched_entity **pse) #endif /* CONFIG_FAIR_GROUP_SCHED */ +static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, + unsigned long delta_exec); /************************************************************** * Scheduling class tree data structure manipulation methods: @@ -334,11 +337,6 @@ static inline int entity_before(struct sched_entity *a, 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; @@ -372,7 +370,6 @@ 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; /* @@ -385,7 +382,7 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) * We dont care about collisions. Nodes with * the same key stay together. */ - if (key < entity_key(cfs_rq, entry)) { + if (entity_before(se, entry)) { link = &parent->rb_left; } else { link = &parent->rb_right; @@ -602,6 +599,8 @@ static void update_curr(struct cfs_rq *cfs_rq) cpuacct_charge(curtask, delta_exec); account_group_exec_runtime(curtask, delta_exec); } + + account_cfs_rq_runtime(cfs_rq, delta_exec); } static inline void @@ -707,6 +706,8 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) } #ifdef CONFIG_FAIR_GROUP_SCHED +/* we need this in update_cfs_load and load-balance functions below */ +static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); # ifdef CONFIG_SMP static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq, int global_update) @@ -729,7 +730,7 @@ static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) u64 now, delta; unsigned long load = cfs_rq->load.weight; - if (cfs_rq->tg == &root_task_group) + if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq)) return; now = rq_of(cfs_rq)->clock_task; @@ -838,7 +839,7 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq) tg = cfs_rq->tg; se = tg->se[cpu_of(rq_of(cfs_rq))]; - if (!se) + if (!se || throttled_hierarchy(cfs_rq)) return; #ifndef CONFIG_SMP if (likely(se->load.weight == tg->shares)) @@ -969,6 +970,8 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) se->vruntime = vruntime; } +static void check_enqueue_throttle(struct cfs_rq *cfs_rq); + static void enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { @@ -998,8 +1001,10 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) __enqueue_entity(cfs_rq, se); se->on_rq = 1; - if (cfs_rq->nr_running == 1) + if (cfs_rq->nr_running == 1) { list_add_leaf_cfs_rq(cfs_rq); + check_enqueue_throttle(cfs_rq); + } } static void __clear_buddies_last(struct sched_entity *se) @@ -1047,6 +1052,8 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) __clear_buddies_skip(se); } +static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); + static void dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { @@ -1085,6 +1092,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) if (!(flags & DEQUEUE_SLEEP)) se->vruntime -= cfs_rq->min_vruntime; + /* return excess runtime on last dequeue */ + return_cfs_rq_runtime(cfs_rq); + update_min_vruntime(cfs_rq); update_cfs_shares(cfs_rq); } @@ -1096,6 +1106,8 @@ static void check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) { unsigned long ideal_runtime, delta_exec; + struct sched_entity *se; + s64 delta; ideal_runtime = sched_slice(cfs_rq, curr); delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; @@ -1114,22 +1126,17 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) * 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_first_entity(cfs_rq); - s64 delta = curr->vruntime - se->vruntime; + se = __pick_first_entity(cfs_rq); + delta = curr->vruntime - se->vruntime; - if (delta < 0) - return; + if (delta < 0) + return; - if (delta > ideal_runtime) - resched_task(rq_of(cfs_rq)->curr); - } + if (delta > ideal_runtime) + resched_task(rq_of(cfs_rq)->curr); } static void @@ -1204,6 +1211,8 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) return se; } +static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq); + static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) { /* @@ -1213,6 +1222,9 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) if (prev->on_rq) update_curr(cfs_rq); + /* throttle cfs_rqs exceeding runtime */ + check_cfs_rq_runtime(cfs_rq); + check_spread(cfs_rq, prev); if (prev->on_rq) { update_stats_wait_start(cfs_rq, prev); @@ -1252,10 +1264,583 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) return; #endif - if (cfs_rq->nr_running > 1 || !sched_feat(WAKEUP_PREEMPT)) + if (cfs_rq->nr_running > 1) check_preempt_tick(cfs_rq, curr); } + +/************************************************** + * CFS bandwidth control machinery + */ + +#ifdef CONFIG_CFS_BANDWIDTH +/* + * default period for cfs group bandwidth. + * default: 0.1s, units: nanoseconds + */ +static inline u64 default_cfs_period(void) +{ + return 100000000ULL; +} + +static inline u64 sched_cfs_bandwidth_slice(void) +{ + return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC; +} + +/* + * Replenish runtime according to assigned quota and update expiration time. + * We use sched_clock_cpu directly instead of rq->clock to avoid adding + * additional synchronization around rq->lock. + * + * requires cfs_b->lock + */ +static void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) +{ + u64 now; + + if (cfs_b->quota == RUNTIME_INF) + return; + + now = sched_clock_cpu(smp_processor_id()); + cfs_b->runtime = cfs_b->quota; + cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period); +} + +/* returns 0 on failure to allocate runtime */ +static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) +{ + struct task_group *tg = cfs_rq->tg; + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg); + u64 amount = 0, min_amount, expires; + + /* note: this is a positive sum as runtime_remaining <= 0 */ + min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining; + + raw_spin_lock(&cfs_b->lock); + if (cfs_b->quota == RUNTIME_INF) + amount = min_amount; + else { + /* + * If the bandwidth pool has become inactive, then at least one + * period must have elapsed since the last consumption. + * Refresh the global state and ensure bandwidth timer becomes + * active. + */ + if (!cfs_b->timer_active) { + __refill_cfs_bandwidth_runtime(cfs_b); + __start_cfs_bandwidth(cfs_b); + } + + if (cfs_b->runtime > 0) { + amount = min(cfs_b->runtime, min_amount); + cfs_b->runtime -= amount; + cfs_b->idle = 0; + } + } + expires = cfs_b->runtime_expires; + raw_spin_unlock(&cfs_b->lock); + + cfs_rq->runtime_remaining += amount; + /* + * we may have advanced our local expiration to account for allowed + * spread between our sched_clock and the one on which runtime was + * issued. + */ + if ((s64)(expires - cfs_rq->runtime_expires) > 0) + cfs_rq->runtime_expires = expires; + + return cfs_rq->runtime_remaining > 0; +} + +/* + * Note: This depends on the synchronization provided by sched_clock and the + * fact that rq->clock snapshots this value. + */ +static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) +{ + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); + struct rq *rq = rq_of(cfs_rq); + + /* if the deadline is ahead of our clock, nothing to do */ + if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0)) + return; + + if (cfs_rq->runtime_remaining < 0) + return; + + /* + * If the local deadline has passed we have to consider the + * possibility that our sched_clock is 'fast' and the global deadline + * has not truly expired. + * + * Fortunately we can check determine whether this the case by checking + * whether the global deadline has advanced. + */ + + if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) { + /* extend local deadline, drift is bounded above by 2 ticks */ + cfs_rq->runtime_expires += TICK_NSEC; + } else { + /* global deadline is ahead, expiration has passed */ + cfs_rq->runtime_remaining = 0; + } +} + +static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, + unsigned long delta_exec) +{ + /* dock delta_exec before expiring quota (as it could span periods) */ + cfs_rq->runtime_remaining -= delta_exec; + expire_cfs_rq_runtime(cfs_rq); + + if (likely(cfs_rq->runtime_remaining > 0)) + return; + + /* + * if we're unable to extend our runtime we resched so that the active + * hierarchy can be throttled + */ + if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr)) + resched_task(rq_of(cfs_rq)->curr); +} + +static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, + unsigned long delta_exec) +{ + if (!cfs_rq->runtime_enabled) + return; + + __account_cfs_rq_runtime(cfs_rq, delta_exec); +} + +static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) +{ + return cfs_rq->throttled; +} + +/* check whether cfs_rq, or any parent, is throttled */ +static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) +{ + return cfs_rq->throttle_count; +} + +/* + * Ensure that neither of the group entities corresponding to src_cpu or + * dest_cpu are members of a throttled hierarchy when performing group + * load-balance operations. + */ +static inline int throttled_lb_pair(struct task_group *tg, + int src_cpu, int dest_cpu) +{ + struct cfs_rq *src_cfs_rq, *dest_cfs_rq; + + src_cfs_rq = tg->cfs_rq[src_cpu]; + dest_cfs_rq = tg->cfs_rq[dest_cpu]; + + return throttled_hierarchy(src_cfs_rq) || + throttled_hierarchy(dest_cfs_rq); +} + +/* updated child weight may affect parent so we have to do this bottom up */ +static int tg_unthrottle_up(struct task_group *tg, void *data) +{ + struct rq *rq = data; + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; + + cfs_rq->throttle_count--; +#ifdef CONFIG_SMP + if (!cfs_rq->throttle_count) { + u64 delta = rq->clock_task - cfs_rq->load_stamp; + + /* leaving throttled state, advance shares averaging windows */ + cfs_rq->load_stamp += delta; + cfs_rq->load_last += delta; + + /* update entity weight now that we are on_rq again */ + update_cfs_shares(cfs_rq); + } +#endif + + return 0; +} + +static int tg_throttle_down(struct task_group *tg, void *data) +{ + struct rq *rq = data; + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; + + /* group is entering throttled state, record last load */ + if (!cfs_rq->throttle_count) + update_cfs_load(cfs_rq, 0); + cfs_rq->throttle_count++; + + return 0; +} + +static void throttle_cfs_rq(struct cfs_rq *cfs_rq) +{ + struct rq *rq = rq_of(cfs_rq); + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); + struct sched_entity *se; + long task_delta, dequeue = 1; + + se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; + + /* account load preceding throttle */ + rcu_read_lock(); + walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); + rcu_read_unlock(); + + task_delta = cfs_rq->h_nr_running; + for_each_sched_entity(se) { + struct cfs_rq *qcfs_rq = cfs_rq_of(se); + /* throttled entity or throttle-on-deactivate */ + if (!se->on_rq) + break; + + if (dequeue) + dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP); + qcfs_rq->h_nr_running -= task_delta; + + if (qcfs_rq->load.weight) + dequeue = 0; + } + + if (!se) + rq->nr_running -= task_delta; + + cfs_rq->throttled = 1; + cfs_rq->throttled_timestamp = rq->clock; + raw_spin_lock(&cfs_b->lock); + list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); + raw_spin_unlock(&cfs_b->lock); +} + +static void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) +{ + struct rq *rq = rq_of(cfs_rq); + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); + struct sched_entity *se; + int enqueue = 1; + long task_delta; + + se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; + + cfs_rq->throttled = 0; + raw_spin_lock(&cfs_b->lock); + cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp; + list_del_rcu(&cfs_rq->throttled_list); + raw_spin_unlock(&cfs_b->lock); + cfs_rq->throttled_timestamp = 0; + + update_rq_clock(rq); + /* update hierarchical throttle state */ + walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); + + if (!cfs_rq->load.weight) + return; + + task_delta = cfs_rq->h_nr_running; + for_each_sched_entity(se) { + if (se->on_rq) + enqueue = 0; + + cfs_rq = cfs_rq_of(se); + if (enqueue) + enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP); + cfs_rq->h_nr_running += task_delta; + + if (cfs_rq_throttled(cfs_rq)) + break; + } + + if (!se) + rq->nr_running += task_delta; + + /* determine whether we need to wake up potentially idle cpu */ + if (rq->curr == rq->idle && rq->cfs.nr_running) + resched_task(rq->curr); +} + +static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b, + u64 remaining, u64 expires) +{ + struct cfs_rq *cfs_rq; + u64 runtime = remaining; + + rcu_read_lock(); + list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq, + throttled_list) { + struct rq *rq = rq_of(cfs_rq); + + raw_spin_lock(&rq->lock); + if (!cfs_rq_throttled(cfs_rq)) + goto next; + + runtime = -cfs_rq->runtime_remaining + 1; + if (runtime > remaining) + runtime = remaining; + remaining -= runtime; + + cfs_rq->runtime_remaining += runtime; + cfs_rq->runtime_expires = expires; + + /* we check whether we're throttled above */ + if (cfs_rq->runtime_remaining > 0) + unthrottle_cfs_rq(cfs_rq); + +next: + raw_spin_unlock(&rq->lock); + + if (!remaining) + break; + } + rcu_read_unlock(); + + return remaining; +} + +/* + * Responsible for refilling a task_group's bandwidth and unthrottling its + * cfs_rqs as appropriate. If there has been no activity within the last + * period the timer is deactivated until scheduling resumes; cfs_b->idle is + * used to track this state. + */ +static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) +{ + u64 runtime, runtime_expires; + int idle = 1, throttled; + + raw_spin_lock(&cfs_b->lock); + /* no need to continue the timer with no bandwidth constraint */ + if (cfs_b->quota == RUNTIME_INF) + goto out_unlock; + + throttled = !list_empty(&cfs_b->throttled_cfs_rq); + /* idle depends on !throttled (for the case of a large deficit) */ + idle = cfs_b->idle && !throttled; + cfs_b->nr_periods += overrun; + + /* if we're going inactive then everything else can be deferred */ + if (idle) + goto out_unlock; + + __refill_cfs_bandwidth_runtime(cfs_b); + + if (!throttled) { + /* mark as potentially idle for the upcoming period */ + cfs_b->idle = 1; + goto out_unlock; + } + + /* account preceding periods in which throttling occurred */ + cfs_b->nr_throttled += overrun; + + /* + * There are throttled entities so we must first use the new bandwidth + * to unthrottle them before making it generally available. This + * ensures that all existing debts will be paid before a new cfs_rq is + * allowed to run. + */ + runtime = cfs_b->runtime; + runtime_expires = cfs_b->runtime_expires; + cfs_b->runtime = 0; + + /* + * This check is repeated as we are holding onto the new bandwidth + * while we unthrottle. This can potentially race with an unthrottled + * group trying to acquire new bandwidth from the global pool. + */ + while (throttled && runtime > 0) { + raw_spin_unlock(&cfs_b->lock); + /* we can't nest cfs_b->lock while distributing bandwidth */ + runtime = distribute_cfs_runtime(cfs_b, runtime, + runtime_expires); + raw_spin_lock(&cfs_b->lock); + + throttled = !list_empty(&cfs_b->throttled_cfs_rq); + } + + /* return (any) remaining runtime */ + cfs_b->runtime = runtime; + /* + * While we are ensured activity in the period following an + * unthrottle, this also covers the case in which the new bandwidth is + * insufficient to cover the existing bandwidth deficit. (Forcing the + * timer to remain active while there are any throttled entities.) + */ + cfs_b->idle = 0; +out_unlock: + if (idle) + cfs_b->timer_active = 0; + raw_spin_unlock(&cfs_b->lock); + + return idle; +} + +/* a cfs_rq won't donate quota below this amount */ +static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC; +/* minimum remaining period time to redistribute slack quota */ +static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; +/* how long we wait to gather additional slack before distributing */ +static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; + +/* are we near the end of the current quota period? */ +static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) +{ + struct hrtimer *refresh_timer = &cfs_b->period_timer; + u64 remaining; + + /* if the call-back is running a quota refresh is already occurring */ + if (hrtimer_callback_running(refresh_timer)) + return 1; + + /* is a quota refresh about to occur? */ + remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); + if (remaining < min_expire) + return 1; + + return 0; +} + +static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b) +{ + u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration; + + /* if there's a quota refresh soon don't bother with slack */ + if (runtime_refresh_within(cfs_b, min_left)) + return; + + start_bandwidth_timer(&cfs_b->slack_timer, + ns_to_ktime(cfs_bandwidth_slack_period)); +} + +/* we know any runtime found here is valid as update_curr() precedes return */ +static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq) +{ + struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); + s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime; + + if (slack_runtime <= 0) + return; + + raw_spin_lock(&cfs_b->lock); + if (cfs_b->quota != RUNTIME_INF && + cfs_rq->runtime_expires == cfs_b->runtime_expires) { + cfs_b->runtime += slack_runtime; + + /* we are under rq->lock, defer unthrottling using a timer */ + if (cfs_b->runtime > sched_cfs_bandwidth_slice() && + !list_empty(&cfs_b->throttled_cfs_rq)) + start_cfs_slack_bandwidth(cfs_b); + } + raw_spin_unlock(&cfs_b->lock); + + /* even if it's not valid for return we don't want to try again */ + cfs_rq->runtime_remaining -= slack_runtime; +} + +static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) +{ + if (!cfs_rq->runtime_enabled || !cfs_rq->nr_running) + return; + + __return_cfs_rq_runtime(cfs_rq); +} + +/* + * This is done with a timer (instead of inline with bandwidth return) since + * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs. + */ +static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) +{ + u64 runtime = 0, slice = sched_cfs_bandwidth_slice(); + u64 expires; + + /* confirm we're still not at a refresh boundary */ + if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) + return; + + raw_spin_lock(&cfs_b->lock); + if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) { + runtime = cfs_b->runtime; + cfs_b->runtime = 0; + } + expires = cfs_b->runtime_expires; + raw_spin_unlock(&cfs_b->lock); + + if (!runtime) + return; + + runtime = distribute_cfs_runtime(cfs_b, runtime, expires); + + raw_spin_lock(&cfs_b->lock); + if (expires == cfs_b->runtime_expires) + cfs_b->runtime = runtime; + raw_spin_unlock(&cfs_b->lock); +} + +/* + * When a group wakes up we want to make sure that its quota is not already + * expired/exceeded, otherwise it may be allowed to steal additional ticks of + * runtime as update_curr() throttling can not not trigger until it's on-rq. + */ +static void check_enqueue_throttle(struct cfs_rq *cfs_rq) +{ + /* an active group must be handled by the update_curr()->put() path */ + if (!cfs_rq->runtime_enabled || cfs_rq->curr) + return; + + /* ensure the group is not already throttled */ + if (cfs_rq_throttled(cfs_rq)) + return; + + /* update runtime allocation */ + account_cfs_rq_runtime(cfs_rq, 0); + if (cfs_rq->runtime_remaining <= 0) + throttle_cfs_rq(cfs_rq); +} + +/* conditionally throttle active cfs_rq's from put_prev_entity() */ +static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) +{ + if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) + return; + + /* + * it's possible for a throttled entity to be forced into a running + * state (e.g. set_curr_task), in this case we're finished. + */ + if (cfs_rq_throttled(cfs_rq)) + return; + + throttle_cfs_rq(cfs_rq); +} +#else +static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, + unsigned long delta_exec) {} +static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} +static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} +static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} + +static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) +{ + return 0; +} + +static inline int throttled_hierarchy(struct cfs_rq *cfs_rq) +{ + return 0; +} + +static inline int throttled_lb_pair(struct task_group *tg, + int src_cpu, int dest_cpu) +{ + return 0; +} +#endif + /************************************************** * CFS operations on tasks: */ @@ -1332,16 +1917,33 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) break; cfs_rq = cfs_rq_of(se); enqueue_entity(cfs_rq, se, flags); + + /* + * end evaluation on encountering a throttled cfs_rq + * + * note: in the case of encountering a throttled cfs_rq we will + * post the final h_nr_running increment below. + */ + if (cfs_rq_throttled(cfs_rq)) + break; + cfs_rq->h_nr_running++; + flags = ENQUEUE_WAKEUP; } for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); + cfs_rq = cfs_rq_of(se); + cfs_rq->h_nr_running++; + + if (cfs_rq_throttled(cfs_rq)) + break; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } + if (!se) + inc_nr_running(rq); hrtick_update(rq); } @@ -1362,6 +1964,16 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) cfs_rq = cfs_rq_of(se); dequeue_entity(cfs_rq, se, flags); + /* + * end evaluation on encountering a throttled cfs_rq + * + * note: in the case of encountering a throttled cfs_rq we will + * post the final h_nr_running decrement below. + */ + if (cfs_rq_throttled(cfs_rq)) + break; + cfs_rq->h_nr_running--; + /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { /* @@ -1370,18 +1982,27 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) */ if (task_sleep && parent_entity(se)) set_next_buddy(parent_entity(se)); + + /* avoid re-evaluating load for this entity */ + se = parent_entity(se); break; } flags |= DEQUEUE_SLEEP; } for_each_sched_entity(se) { - struct cfs_rq *cfs_rq = cfs_rq_of(se); + cfs_rq = cfs_rq_of(se); + cfs_rq->h_nr_running--; + + if (cfs_rq_throttled(cfs_rq)) + break; update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); } + if (!se) + dec_nr_running(rq); hrtick_update(rq); } @@ -1450,7 +2071,6 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) return wl; } - #else static inline unsigned long effective_load(struct task_group *tg, int cpu, @@ -1481,7 +2101,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) * effect of the currently running task from the load * of the current CPU: */ - rcu_read_lock(); if (sync) { tg = task_group(current); weight = current->se.load.weight; @@ -1517,7 +2136,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) balanced = this_eff_load <= prev_eff_load; } else balanced = true; - rcu_read_unlock(); /* * If the currently running task will sleep within @@ -1565,7 +2183,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, /* Skip over this group if it has no CPUs allowed */ if (!cpumask_intersects(sched_group_cpus(group), - &p->cpus_allowed)) + tsk_cpus_allowed(p))) continue; local_group = cpumask_test_cpu(this_cpu, @@ -1585,7 +2203,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, } /* Adjust by relative CPU power of the group */ - avg_load = (avg_load * SCHED_POWER_SCALE) / group->cpu_power; + avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power; if (local_group) { this_load = avg_load; @@ -1611,7 +2229,7 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) int i; /* Traverse only the allowed CPUs */ - for_each_cpu_and(i, sched_group_cpus(group), &p->cpus_allowed) { + for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { load = weighted_cpuload(i); if (load < min_load || (load == min_load && i == this_cpu)) { @@ -1655,7 +2273,7 @@ static int select_idle_sibling(struct task_struct *p, int target) if (!(sd->flags & SD_SHARE_PKG_RESOURCES)) break; - for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) { + for_each_cpu_and(i, sched_domain_span(sd), tsk_cpus_allowed(p)) { if (idle_cpu(i)) { target = i; break; @@ -1698,7 +2316,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) int sync = wake_flags & WF_SYNC; if (sd_flag & SD_BALANCE_WAKE) { - if (cpumask_test_cpu(cpu, &p->cpus_allowed)) + if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) want_affine = 1; new_cpu = prev_cpu; } @@ -1893,6 +2511,15 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ if (unlikely(se == pse)) return; + /* + * This is possible from callers such as pull_task(), in which we + * unconditionally check_prempt_curr() after an enqueue (which may have + * lead to a throttle). This both saves work and prevents false + * next-buddy nomination below. + */ + if (unlikely(throttled_hierarchy(cfs_rq_of(pse)))) + return; + if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) { set_next_buddy(pse); next_buddy_marked = 1; @@ -1901,6 +2528,12 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ /* * We can come here with TIF_NEED_RESCHED already set from new task * wake up path. + * + * Note: this also catches the edge-case of curr being in a throttled + * group (e.g. via set_curr_task), since update_curr() (in the + * enqueue of curr) will have resulted in resched being set. This + * prevents us from potentially nominating it as a false LAST_BUDDY + * below. */ if (test_tsk_need_resched(curr)) return; @@ -1917,12 +2550,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ if (unlikely(p->policy != SCHED_NORMAL)) return; - - if (!sched_feat(WAKEUP_PREEMPT)) - return; - - update_curr(cfs_rq); find_matching_se(&se, &pse); + update_curr(cfs_rq_of(se)); BUG_ON(!pse); if (wakeup_preempt_entity(se, pse) == 1) { /* @@ -2023,7 +2652,8 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp { struct sched_entity *se = &p->se; - if (!se->on_rq) + /* throttled hierarchies are not runnable */ + if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se))) return false; /* Tell the scheduler that we'd really like pse to run next. */ @@ -2067,7 +2697,7 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, * 2) cannot be migrated to this CPU due to cpus_allowed, or * 3) are cache-hot on their current CPU. */ - if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) { + if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) { schedstat_inc(p, se.statistics.nr_failed_migrations_affine); return 0; } @@ -2120,6 +2750,9 @@ move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, for_each_leaf_cfs_rq(busiest, cfs_rq) { list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) { + if (throttled_lb_pair(task_group(p), + busiest->cpu, this_cpu)) + break; if (!can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) @@ -2231,11 +2864,48 @@ static void update_shares(int cpu) struct rq *rq = cpu_rq(cpu); rcu_read_lock(); - for_each_leaf_cfs_rq(rq, cfs_rq) + /* + * Iterates the task_group tree in a bottom up fashion, see + * list_add_leaf_cfs_rq() for details. + */ + for_each_leaf_cfs_rq(rq, cfs_rq) { + /* throttled entities do not contribute to load */ + if (throttled_hierarchy(cfs_rq)) + continue; + update_shares_cpu(cfs_rq->tg, cpu); + } rcu_read_unlock(); } +/* + * Compute the cpu's hierarchical load factor for each task group. + * This needs to be done in a top-down fashion because the load of a child + * group is a fraction of its parents load. + */ +static int tg_load_down(struct task_group *tg, void *data) +{ + unsigned long load; + long cpu = (long)data; + + if (!tg->parent) { + load = cpu_rq(cpu)->load.weight; + } else { + load = tg->parent->cfs_rq[cpu]->h_load; + load *= tg->se[cpu]->load.weight; + load /= tg->parent->cfs_rq[cpu]->load.weight + 1; + } + + tg->cfs_rq[cpu]->h_load = load; + + return 0; +} + +static void update_h_load(long cpu) +{ + walk_tg_tree(tg_load_down, tg_nop, (void *)cpu); +} + static unsigned long load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, unsigned long max_load_move, @@ -2243,22 +2913,21 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, int *all_pinned) { long rem_load_move = max_load_move; - int busiest_cpu = cpu_of(busiest); - struct task_group *tg; + struct cfs_rq *busiest_cfs_rq; rcu_read_lock(); - update_h_load(busiest_cpu); + update_h_load(cpu_of(busiest)); - list_for_each_entry_rcu(tg, &task_groups, list) { - struct cfs_rq *busiest_cfs_rq = tg->cfs_rq[busiest_cpu]; + for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) { 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 + * empty group or part of a throttled hierarchy */ - if (!busiest_cfs_rq->task_weight) + if (!busiest_cfs_rq->task_weight || + throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu)) continue; rem_load = (u64)rem_load_move * busiest_weight; @@ -2631,7 +3300,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu) power >>= SCHED_POWER_SHIFT; } - sdg->cpu_power_orig = power; + sdg->sgp->power_orig = power; if (sched_feat(ARCH_POWER)) power *= arch_scale_freq_power(sd, cpu); @@ -2647,7 +3316,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu) power = 1; cpu_rq(cpu)->cpu_power = power; - sdg->cpu_power = power; + sdg->sgp->power = power; } static void update_group_power(struct sched_domain *sd, int cpu) @@ -2665,11 +3334,11 @@ static void update_group_power(struct sched_domain *sd, int cpu) group = child->groups; do { - power += group->cpu_power; + power += group->sgp->power; group = group->next; } while (group != child->groups); - sdg->cpu_power = power; + sdg->sgp->power = power; } /* @@ -2691,7 +3360,7 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group) /* * If ~90% of the cpu_power is still there, we're good. */ - if (group->cpu_power * 32 > group->cpu_power_orig * 29) + if (group->sgp->power * 32 > group->sgp->power_orig * 29) return 1; return 0; @@ -2771,7 +3440,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, } /* Adjust by relative CPU power of the group */ - sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->cpu_power; + sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power; /* * Consider the group unbalanced when the imbalance is larger @@ -2788,7 +3457,7 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1) sgs->group_imb = 1; - sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power, + sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power, SCHED_POWER_SCALE); if (!sgs->group_capacity) sgs->group_capacity = fix_small_capacity(sd, group); @@ -2877,7 +3546,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, return; sds->total_load += sgs.group_load; - sds->total_pwr += sg->cpu_power; + sds->total_pwr += sg->sgp->power; /* * In case the child domain prefers tasks go to siblings @@ -2962,7 +3631,7 @@ static int check_asym_packing(struct sched_domain *sd, if (this_cpu > busiest_cpu) return 0; - *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->cpu_power, + *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE); return 1; } @@ -2993,7 +3662,7 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, scaled_busy_load_per_task = sds->busiest_load_per_task * SCHED_POWER_SCALE; - scaled_busy_load_per_task /= sds->busiest->cpu_power; + scaled_busy_load_per_task /= sds->busiest->sgp->power; if (sds->max_load - sds->this_load + scaled_busy_load_per_task >= (scaled_busy_load_per_task * imbn)) { @@ -3007,28 +3676,28 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, * moving them. */ - pwr_now += sds->busiest->cpu_power * + pwr_now += sds->busiest->sgp->power * min(sds->busiest_load_per_task, sds->max_load); - pwr_now += sds->this->cpu_power * + pwr_now += sds->this->sgp->power * min(sds->this_load_per_task, sds->this_load); pwr_now /= SCHED_POWER_SCALE; /* Amount of load we'd subtract */ tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->busiest->cpu_power; + sds->busiest->sgp->power; if (sds->max_load > tmp) - pwr_move += sds->busiest->cpu_power * + pwr_move += sds->busiest->sgp->power * min(sds->busiest_load_per_task, sds->max_load - tmp); /* Amount of load we'd add */ - if (sds->max_load * sds->busiest->cpu_power < + if (sds->max_load * sds->busiest->sgp->power < sds->busiest_load_per_task * SCHED_POWER_SCALE) - tmp = (sds->max_load * sds->busiest->cpu_power) / - sds->this->cpu_power; + tmp = (sds->max_load * sds->busiest->sgp->power) / + sds->this->sgp->power; else tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->this->cpu_power; - pwr_move += sds->this->cpu_power * + sds->this->sgp->power; + pwr_move += sds->this->sgp->power * min(sds->this_load_per_task, sds->this_load + tmp); pwr_move /= SCHED_POWER_SCALE; @@ -3074,7 +3743,7 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE); - load_above_capacity /= sds->busiest->cpu_power; + load_above_capacity /= sds->busiest->sgp->power; } /* @@ -3090,8 +3759,8 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, max_pull = min(sds->max_load - sds->avg_load, load_above_capacity); /* How much load to actually move to equalise the imbalance */ - *imbalance = min(max_pull * sds->busiest->cpu_power, - (sds->avg_load - sds->this_load) * sds->this->cpu_power) + *imbalance = min(max_pull * sds->busiest->sgp->power, + (sds->avg_load - sds->this_load) * sds->this->sgp->power) / SCHED_POWER_SCALE; /* @@ -3418,7 +4087,7 @@ redo: * moved to this_cpu */ if (!cpumask_test_cpu(this_cpu, - &busiest->curr->cpus_allowed)) { + tsk_cpus_allowed(busiest->curr))) { raw_spin_unlock_irqrestore(&busiest->lock, flags); all_pinned = 1; @@ -3600,22 +4269,6 @@ out_unlock: } #ifdef CONFIG_NO_HZ - -static DEFINE_PER_CPU(struct call_single_data, remote_sched_softirq_cb); - -static void trigger_sched_softirq(void *data) -{ - raise_softirq_irqoff(SCHED_SOFTIRQ); -} - -static inline void init_sched_softirq_csd(struct call_single_data *csd) -{ - csd->func = trigger_sched_softirq; - csd->info = NULL; - csd->flags = 0; - csd->priv = 0; -} - /* * idle load balancing details * - One of the idle CPUs nominates itself as idle load_balancer, while @@ -3655,7 +4308,7 @@ static inline struct sched_domain *lowest_flag_domain(int cpu, int flag) struct sched_domain *sd; for_each_domain(cpu, sd) - if (sd && (sd->flags & flag)) + if (sd->flags & flag) break; return sd; @@ -3781,11 +4434,16 @@ static void nohz_balancer_kick(int cpu) } if (!cpu_rq(ilb_cpu)->nohz_balance_kick) { - struct call_single_data *cp; - cpu_rq(ilb_cpu)->nohz_balance_kick = 1; - cp = &per_cpu(remote_sched_softirq_cb, cpu); - __smp_call_function_single(ilb_cpu, cp, 0); + + smp_mb(); + /* + * Use smp_send_reschedule() instead of resched_cpu(). + * This way we generate a sched IPI on the target cpu which + * is idle. And the softirq performing nohz idle load balance + * will be run before returning from the IPI. + */ + smp_send_reschedule(ilb_cpu); } return; } @@ -4018,7 +4676,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) if (time_before(now, nohz.next_balance)) return 0; - if (rq->idle_at_tick) + if (idle_cpu(cpu)) return 0; first_pick_cpu = atomic_read(&nohz.first_pick_cpu); @@ -4054,7 +4712,7 @@ static void run_rebalance_domains(struct softirq_action *h) { int this_cpu = smp_processor_id(); struct rq *this_rq = cpu_rq(this_cpu); - enum cpu_idle_type idle = this_rq->idle_at_tick ? + enum cpu_idle_type idle = this_rq->idle_balance ? CPU_IDLE : CPU_NOT_IDLE; rebalance_domains(this_cpu, idle); @@ -4239,8 +4897,13 @@ 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); + for_each_sched_entity(se) { + struct cfs_rq *cfs_rq = cfs_rq_of(se); + + set_next_entity(cfs_rq, se); + /* ensure bandwidth has been allocated on our new cfs_rq */ + account_cfs_rq_runtime(cfs_rq, 0); + } } #ifdef CONFIG_FAIR_GROUP_SCHED |