sched: Add support for throttling group entities
Now that consumption is tracked (via update_curr()) we add support to throttle group entities (and their corresponding cfs_rqs) in the case where this is no run-time remaining. Throttled entities are dequeued to prevent scheduling, additionally we mark them as throttled (using cfs_rq->throttled) to prevent them from becoming re-enqueued until they are unthrottled. A list of a task_group's throttled entities are maintained on the cfs_bandwidth structure. Note: While the machinery for throttling is added in this patch the act of throttling an entity exceeding its bandwidth is deferred until later within the series. Signed-off-by: Paul Turner <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110721184757.480608533@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -260,6 +260,8 @@ struct cfs_bandwidth {
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int idle, timer_active;
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int idle, timer_active;
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struct hrtimer period_timer;
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struct hrtimer period_timer;
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struct list_head throttled_cfs_rq;
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#endif
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#endif
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};
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};
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@ -399,6 +401,9 @@ struct cfs_rq {
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int runtime_enabled;
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int runtime_enabled;
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u64 runtime_expires;
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u64 runtime_expires;
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s64 runtime_remaining;
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s64 runtime_remaining;
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int throttled;
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struct list_head throttled_list;
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#endif
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#endif
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#endif
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#endif
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};
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};
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@ -441,6 +446,7 @@ static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
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cfs_b->quota = RUNTIME_INF;
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cfs_b->quota = RUNTIME_INF;
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cfs_b->period = ns_to_ktime(default_cfs_period());
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cfs_b->period = ns_to_ktime(default_cfs_period());
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INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
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hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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cfs_b->period_timer.function = sched_cfs_period_timer;
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cfs_b->period_timer.function = sched_cfs_period_timer;
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}
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}
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@ -448,6 +454,7 @@ static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
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static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
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static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
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{
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{
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cfs_rq->runtime_enabled = 0;
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cfs_rq->runtime_enabled = 0;
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INIT_LIST_HEAD(&cfs_rq->throttled_list);
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}
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}
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/* requires cfs_b->lock, may release to reprogram timer */
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/* requires cfs_b->lock, may release to reprogram timer */
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@ -1291,7 +1291,8 @@ static void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
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cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
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cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
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}
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}
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static void assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
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/* returns 0 on failure to allocate runtime */
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static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
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{
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{
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struct task_group *tg = cfs_rq->tg;
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struct task_group *tg = cfs_rq->tg;
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struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
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struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
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@ -1332,6 +1333,8 @@ static void assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
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*/
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*/
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if ((s64)(expires - cfs_rq->runtime_expires) > 0)
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if ((s64)(expires - cfs_rq->runtime_expires) > 0)
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cfs_rq->runtime_expires = expires;
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cfs_rq->runtime_expires = expires;
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return cfs_rq->runtime_remaining > 0;
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}
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}
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/*
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/*
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@ -1378,7 +1381,12 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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if (likely(cfs_rq->runtime_remaining > 0))
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if (likely(cfs_rq->runtime_remaining > 0))
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return;
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return;
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assign_cfs_rq_runtime(cfs_rq);
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/*
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* if we're unable to extend our runtime we resched so that the active
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* hierarchy can be throttled
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*/
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if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
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resched_task(rq_of(cfs_rq)->curr);
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}
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}
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static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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@ -1390,6 +1398,47 @@ static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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__account_cfs_rq_runtime(cfs_rq, delta_exec);
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__account_cfs_rq_runtime(cfs_rq, delta_exec);
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}
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}
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static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->throttled;
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}
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static __used void throttle_cfs_rq(struct cfs_rq *cfs_rq)
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{
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struct rq *rq = rq_of(cfs_rq);
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struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
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struct sched_entity *se;
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long task_delta, dequeue = 1;
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se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
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/* account load preceding throttle */
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update_cfs_load(cfs_rq, 0);
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task_delta = cfs_rq->h_nr_running;
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for_each_sched_entity(se) {
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struct cfs_rq *qcfs_rq = cfs_rq_of(se);
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/* throttled entity or throttle-on-deactivate */
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if (!se->on_rq)
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break;
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if (dequeue)
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dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
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qcfs_rq->h_nr_running -= task_delta;
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if (qcfs_rq->load.weight)
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dequeue = 0;
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}
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if (!se)
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rq->nr_running -= task_delta;
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cfs_rq->throttled = 1;
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raw_spin_lock(&cfs_b->lock);
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list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
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raw_spin_unlock(&cfs_b->lock);
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}
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/*
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/*
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* Responsible for refilling a task_group's bandwidth and unthrottling its
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* Responsible for refilling a task_group's bandwidth and unthrottling its
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* cfs_rqs as appropriate. If there has been no activity within the last
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* cfs_rqs as appropriate. If there has been no activity within the last
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@ -1425,6 +1474,11 @@ out_unlock:
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#else
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#else
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static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
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unsigned long delta_exec) {}
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unsigned long delta_exec) {}
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static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
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{
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return 0;
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}
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#endif
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#endif
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/**************************************************
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/**************************************************
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@ -1503,7 +1557,17 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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break;
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break;
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cfs_rq = cfs_rq_of(se);
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cfs_rq = cfs_rq_of(se);
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enqueue_entity(cfs_rq, se, flags);
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enqueue_entity(cfs_rq, se, flags);
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/*
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* end evaluation on encountering a throttled cfs_rq
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*
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* note: in the case of encountering a throttled cfs_rq we will
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* post the final h_nr_running increment below.
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*/
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if (cfs_rq_throttled(cfs_rq))
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break;
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cfs_rq->h_nr_running++;
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cfs_rq->h_nr_running++;
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flags = ENQUEUE_WAKEUP;
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flags = ENQUEUE_WAKEUP;
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}
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}
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@ -1511,11 +1575,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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cfs_rq = cfs_rq_of(se);
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cfs_rq = cfs_rq_of(se);
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cfs_rq->h_nr_running++;
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cfs_rq->h_nr_running++;
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if (cfs_rq_throttled(cfs_rq))
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break;
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update_cfs_load(cfs_rq, 0);
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update_cfs_load(cfs_rq, 0);
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq);
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}
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}
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inc_nr_running(rq);
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if (!se)
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inc_nr_running(rq);
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hrtick_update(rq);
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hrtick_update(rq);
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}
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}
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@ -1535,6 +1603,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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for_each_sched_entity(se) {
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for_each_sched_entity(se) {
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cfs_rq = cfs_rq_of(se);
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cfs_rq = cfs_rq_of(se);
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dequeue_entity(cfs_rq, se, flags);
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dequeue_entity(cfs_rq, se, flags);
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/*
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* end evaluation on encountering a throttled cfs_rq
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*
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* note: in the case of encountering a throttled cfs_rq we will
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* post the final h_nr_running decrement below.
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*/
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if (cfs_rq_throttled(cfs_rq))
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break;
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cfs_rq->h_nr_running--;
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cfs_rq->h_nr_running--;
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/* Don't dequeue parent if it has other entities besides us */
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/* Don't dequeue parent if it has other entities besides us */
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@ -1557,11 +1634,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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cfs_rq = cfs_rq_of(se);
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cfs_rq = cfs_rq_of(se);
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cfs_rq->h_nr_running--;
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cfs_rq->h_nr_running--;
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if (cfs_rq_throttled(cfs_rq))
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break;
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update_cfs_load(cfs_rq, 0);
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update_cfs_load(cfs_rq, 0);
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update_cfs_shares(cfs_rq);
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update_cfs_shares(cfs_rq);
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}
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}
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dec_nr_running(rq);
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if (!se)
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dec_nr_running(rq);
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hrtick_update(rq);
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hrtick_update(rq);
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}
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}
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