diff options
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 96 |
1 files changed, 59 insertions, 37 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 01859f662ab7..d3c03070872d 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -22,7 +22,7 @@ /* * Targeted preemption latency for CPU-bound tasks: - * (default: 20ms, units: nanoseconds) + * (default: 20ms * 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 @@ -32,19 +32,24 @@ * (to see the precise effective timeslice length of your workload, * run vmstat and monitor the context-switches (cs) field) */ -const_debug unsigned int sysctl_sched_latency = 20000000ULL; +unsigned int sysctl_sched_latency = 20000000ULL; /* - * After fork, child runs first. (default) If set to 0 then - * parent will (try to) run first. + * Minimal preemption granularity for CPU-bound tasks: + * (default: 1 msec * ilog(ncpus), units: nanoseconds) */ -const_debug unsigned int sysctl_sched_child_runs_first = 1; +unsigned int sysctl_sched_min_granularity = 1000000ULL; /* - * Minimal preemption granularity for CPU-bound tasks: - * (default: 2 msec, units: nanoseconds) + * is kept at sysctl_sched_latency / sysctl_sched_min_granularity + */ +unsigned int sched_nr_latency = 20; + +/* + * After fork, child runs first. (default) If set to 0 then + * parent will (try to) run first. */ -const_debug unsigned int sysctl_sched_nr_latency = 20; +const_debug unsigned int sysctl_sched_child_runs_first = 1; /* * sys_sched_yield() compat mode @@ -56,23 +61,23 @@ unsigned int __read_mostly sysctl_sched_compat_yield; /* * SCHED_BATCH wake-up granularity. - * (default: 10 msec, units: nanoseconds) + * (default: 10 msec * 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. */ -const_debug unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL; +unsigned int sysctl_sched_batch_wakeup_granularity = 10000000UL; /* * SCHED_OTHER wake-up granularity. - * (default: 10 msec, units: nanoseconds) + * (default: 10 msec * 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. */ -const_debug unsigned int sysctl_sched_wakeup_granularity = 10000000UL; +unsigned int sysctl_sched_wakeup_granularity = 10000000UL; const_debug unsigned int sysctl_sched_migration_cost = 500000UL; @@ -212,6 +217,22 @@ static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) * Scheduling class statistics methods: */ +#ifdef CONFIG_SCHED_DEBUG +int sched_nr_latency_handler(struct ctl_table *table, int write, + struct file *filp, void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos); + + if (ret || !write) + return ret; + + sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency, + sysctl_sched_min_granularity); + + return 0; +} +#endif /* * The idea is to set a period in which each task runs once. @@ -224,7 +245,7 @@ static inline struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq) static u64 __sched_period(unsigned long nr_running) { u64 period = sysctl_sched_latency; - unsigned long nr_latency = sysctl_sched_nr_latency; + unsigned long nr_latency = sched_nr_latency; if (unlikely(nr_running > nr_latency)) { period *= nr_running; @@ -259,6 +280,7 @@ static u64 __sched_vslice(unsigned long rq_weight, unsigned long nr_running) { u64 vslice = __sched_period(nr_running); + vslice *= NICE_0_LOAD; do_div(vslice, rq_weight); return vslice; @@ -472,19 +494,26 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) } else if (sched_feat(APPROX_AVG) && cfs_rq->nr_running) vruntime += sched_vslice(cfs_rq)/2; + /* + * The 'current' period is already promised to the current tasks, + * however the extra weight of the new task will slow them down a + * little, place the new task so that it fits in the slot that + * stays open at the end. + */ if (initial && sched_feat(START_DEBIT)) vruntime += sched_vslice_add(cfs_rq, se); if (!initial) { + /* sleeps upto a single latency don't count. */ if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se) && task_of(se)->policy != SCHED_BATCH) vruntime -= sysctl_sched_latency; - vruntime = max_t(s64, vruntime, se->vruntime); + /* ensure we never gain time by being placed backwards. */ + vruntime = max_vruntime(se->vruntime, vruntime); } se->vruntime = vruntime; - } static void @@ -517,7 +546,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep) update_stats_dequeue(cfs_rq, se); if (sleep) { - se->peer_preempt = 0; #ifdef CONFIG_SCHEDSTATS if (entity_is_task(se)) { struct task_struct *tsk = task_of(se); @@ -545,10 +573,8 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) ideal_runtime = sched_slice(cfs_rq, curr); delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; - if (delta_exec > ideal_runtime || - (sched_feat(PREEMPT_RESTRICT) && curr->peer_preempt)) + if (delta_exec > ideal_runtime) resched_task(rq_of(cfs_rq)->curr); - curr->peer_preempt = 0; } static void @@ -811,7 +837,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) struct task_struct *curr = rq->curr; struct cfs_rq *cfs_rq = task_cfs_rq(curr); struct sched_entity *se = &curr->se, *pse = &p->se; - s64 delta, gran; + unsigned long gran; if (unlikely(rt_prio(p->prio))) { update_rq_clock(rq); @@ -826,24 +852,20 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p) if (unlikely(p->policy == SCHED_BATCH)) return; - if (sched_feat(WAKEUP_PREEMPT)) { - while (!is_same_group(se, pse)) { - se = parent_entity(se); - pse = parent_entity(pse); - } + if (!sched_feat(WAKEUP_PREEMPT)) + return; - delta = se->vruntime - pse->vruntime; - gran = sysctl_sched_wakeup_granularity; - if (unlikely(se->load.weight != NICE_0_LOAD)) - gran = calc_delta_fair(gran, &se->load); + while (!is_same_group(se, pse)) { + se = parent_entity(se); + pse = parent_entity(pse); + } - if (delta > gran) { - int now = !sched_feat(PREEMPT_RESTRICT); + gran = sysctl_sched_wakeup_granularity; + if (unlikely(se->load.weight != NICE_0_LOAD)) + gran = calc_delta_fair(gran, &se->load); - if (now || p->prio < curr->prio || !se->peer_preempt++) - resched_task(curr); - } - } + if (pse->vruntime + gran < se->vruntime) + resched_task(curr); } static struct task_struct *pick_next_task_fair(struct rq *rq) @@ -1045,8 +1067,9 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) update_curr(cfs_rq); place_entity(cfs_rq, se, 1); + /* 'curr' will be NULL if the child belongs to a different group */ if (sysctl_sched_child_runs_first && this_cpu == task_cpu(p) && - curr->vruntime < se->vruntime) { + curr && curr->vruntime < se->vruntime) { /* * Upon rescheduling, sched_class::put_prev_task() will place * 'current' within the tree based on its new key value. @@ -1054,7 +1077,6 @@ static void task_new_fair(struct rq *rq, struct task_struct *p) swap(curr->vruntime, se->vruntime); } - se->peer_preempt = 0; enqueue_task_fair(rq, p, 0); resched_task(rq->curr); } |