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sched: rt-group: smp balancing
Currently the rt group scheduling does a per cpu runtime limit, however the rt load balancer makes no guarantees about an equal spread of real- time tasks, just that at any one time, the highest priority tasks run. Solve this by making the runtime limit a global property by borrowing excessive runtime from the other cpus once the local limit runs out. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
Ingo Molnar
parent
d0b27fa778
commit
ac086bc229
@ -164,6 +164,7 @@ struct rt_prio_array {
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struct rt_bandwidth {
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ktime_t rt_period;
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u64 rt_runtime;
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spinlock_t rt_runtime_lock;
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struct hrtimer rt_period_timer;
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};
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@ -198,6 +199,8 @@ void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
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rt_b->rt_period = ns_to_ktime(period);
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rt_b->rt_runtime = runtime;
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spin_lock_init(&rt_b->rt_runtime_lock);
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hrtimer_init(&rt_b->rt_period_timer,
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CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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rt_b->rt_period_timer.function = sched_rt_period_timer;
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@ -414,6 +417,8 @@ struct rt_rq {
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#endif
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int rt_throttled;
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u64 rt_time;
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u64 rt_runtime;
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spinlock_t rt_runtime_lock;
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#ifdef CONFIG_RT_GROUP_SCHED
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unsigned long rt_nr_boosted;
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@ -7299,6 +7304,8 @@ static void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq)
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rt_rq->rt_time = 0;
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rt_rq->rt_throttled = 0;
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rt_rq->rt_runtime = 0;
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spin_lock_init(&rt_rq->rt_runtime_lock);
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#ifdef CONFIG_RT_GROUP_SCHED
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rt_rq->rt_nr_boosted = 0;
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@ -7335,6 +7342,7 @@ static void init_tg_rt_entry(struct rq *rq, struct task_group *tg,
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init_rt_rq(rt_rq, rq);
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rt_rq->tg = tg;
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rt_rq->rt_se = rt_se;
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rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
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if (add)
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list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
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@ -7391,6 +7399,8 @@ void __init sched_init(void)
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init_tg_rt_entry(rq, &init_task_group,
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&per_cpu(init_rt_rq, i),
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&per_cpu(init_sched_rt_entity, i), i, 1);
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#else
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rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
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#endif
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for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
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@ -7974,11 +7984,11 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
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static int tg_set_bandwidth(struct task_group *tg,
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u64 rt_period, u64 rt_runtime)
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{
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int err = 0;
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int i, err = 0;
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mutex_lock(&rt_constraints_mutex);
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read_lock(&tasklist_lock);
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if (rt_runtime_us == 0 && tg_has_rt_tasks(tg)) {
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if (rt_runtime == 0 && tg_has_rt_tasks(tg)) {
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err = -EBUSY;
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goto unlock;
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}
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@ -7986,8 +7996,19 @@ static int tg_set_bandwidth(struct task_group *tg,
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err = -EINVAL;
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goto unlock;
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}
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spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
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tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
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tg->rt_bandwidth.rt_runtime = rt_runtime;
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for_each_possible_cpu(i) {
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struct rt_rq *rt_rq = tg->rt_rq[i];
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spin_lock(&rt_rq->rt_runtime_lock);
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rt_rq->rt_runtime = rt_runtime;
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spin_unlock(&rt_rq->rt_runtime_lock);
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}
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spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
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unlock:
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read_unlock(&tasklist_lock);
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mutex_unlock(&rt_constraints_mutex);
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@ -8052,6 +8073,19 @@ static int sched_rt_global_constraints(void)
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#else
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static int sched_rt_global_constraints(void)
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{
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unsigned long flags;
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int i;
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spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
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for_each_possible_cpu(i) {
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struct rt_rq *rt_rq = &cpu_rq(i)->rt;
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spin_lock(&rt_rq->rt_runtime_lock);
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rt_rq->rt_runtime = global_rt_runtime();
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spin_unlock(&rt_rq->rt_runtime_lock);
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}
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spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
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return 0;
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}
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#endif
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@ -8168,7 +8202,7 @@ static u64 cpu_shares_read_uint(struct cgroup *cgrp, struct cftype *cft)
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#endif
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#ifdef CONFIG_RT_GROUP_SCHED
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static int cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
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static ssize_t cpu_rt_runtime_write(struct cgroup *cgrp, struct cftype *cft,
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struct file *file,
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const char __user *userbuf,
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size_t nbytes, loff_t *unused_ppos)
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@ -62,7 +62,12 @@ static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
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if (!rt_rq->tg)
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return RUNTIME_INF;
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return rt_rq->tg->rt_bandwidth.rt_runtime;
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return rt_rq->rt_runtime;
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}
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static inline u64 sched_rt_period(struct rt_rq *rt_rq)
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{
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return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
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}
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#define for_each_leaf_rt_rq(rt_rq, rq) \
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@ -145,11 +150,21 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
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return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
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}
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static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
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{
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return &rt_rq->tg->rt_bandwidth;
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}
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#else
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static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
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{
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return def_rt_bandwidth.rt_runtime;
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return rt_rq->rt_runtime;
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}
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static inline u64 sched_rt_period(struct rt_rq *rt_rq)
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{
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return ktime_to_ns(def_rt_bandwidth.rt_period);
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}
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#define for_each_leaf_rt_rq(rt_rq, rq) \
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@ -200,6 +215,11 @@ struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
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return &cpu_rq(cpu)->rt;
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}
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static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
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{
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return &def_rt_bandwidth;
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}
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#endif
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static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
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@ -218,8 +238,10 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
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spin_lock(&rq->lock);
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if (rt_rq->rt_time) {
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u64 runtime = rt_b->rt_runtime;
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u64 runtime;
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spin_lock(&rt_rq->rt_runtime_lock);
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runtime = rt_rq->rt_runtime;
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rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
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if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
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rt_rq->rt_throttled = 0;
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@ -227,6 +249,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
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}
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if (rt_rq->rt_time || rt_rq->rt_nr_running)
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idle = 0;
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spin_unlock(&rt_rq->rt_runtime_lock);
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}
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if (enqueue)
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@ -237,6 +260,47 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
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return idle;
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}
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#ifdef CONFIG_SMP
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static int balance_runtime(struct rt_rq *rt_rq)
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{
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struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
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struct root_domain *rd = cpu_rq(smp_processor_id())->rd;
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int i, weight, more = 0;
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u64 rt_period;
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weight = cpus_weight(rd->span);
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spin_lock(&rt_b->rt_runtime_lock);
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rt_period = ktime_to_ns(rt_b->rt_period);
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for_each_cpu_mask(i, rd->span) {
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struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
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s64 diff;
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if (iter == rt_rq)
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continue;
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spin_lock(&iter->rt_runtime_lock);
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diff = iter->rt_runtime - iter->rt_time;
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if (diff > 0) {
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do_div(diff, weight);
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if (rt_rq->rt_runtime + diff > rt_period)
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diff = rt_period - rt_rq->rt_runtime;
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iter->rt_runtime -= diff;
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rt_rq->rt_runtime += diff;
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more = 1;
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if (rt_rq->rt_runtime == rt_period) {
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spin_unlock(&iter->rt_runtime_lock);
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break;
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}
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}
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spin_unlock(&iter->rt_runtime_lock);
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}
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spin_unlock(&rt_b->rt_runtime_lock);
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return more;
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}
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#endif
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static inline int rt_se_prio(struct sched_rt_entity *rt_se)
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{
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#ifdef CONFIG_RT_GROUP_SCHED
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@ -259,6 +323,22 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
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if (rt_rq->rt_throttled)
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return rt_rq_throttled(rt_rq);
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if (sched_rt_runtime(rt_rq) >= sched_rt_period(rt_rq))
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return 0;
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#ifdef CONFIG_SMP
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if (rt_rq->rt_time > runtime) {
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int more;
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spin_unlock(&rt_rq->rt_runtime_lock);
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more = balance_runtime(rt_rq);
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spin_lock(&rt_rq->rt_runtime_lock);
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if (more)
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runtime = sched_rt_runtime(rt_rq);
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}
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#endif
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if (rt_rq->rt_time > runtime) {
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rt_rq->rt_throttled = 1;
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if (rt_rq_throttled(rt_rq)) {
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@ -294,9 +374,11 @@ static void update_curr_rt(struct rq *rq)
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curr->se.exec_start = rq->clock;
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cpuacct_charge(curr, delta_exec);
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spin_lock(&rt_rq->rt_runtime_lock);
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rt_rq->rt_time += delta_exec;
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if (sched_rt_runtime_exceeded(rt_rq))
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resched_task(curr);
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spin_unlock(&rt_rq->rt_runtime_lock);
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}
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static inline
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