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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>
hifive-unleashed-5.1
Paul Turner 2011-07-21 09:43:33 -07:00 committed by Ingo Molnar
parent a9cf55b286
commit 85dac906be
2 changed files with 92 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/sched.c
View File

@ -260,6 +260,8 @@ struct cfs_bandwidth {
int idle, timer_active;
struct hrtimer period_timer;
struct list_head throttled_cfs_rq;
#endif
};
@ -399,6 +401,9 @@ struct cfs_rq {
int runtime_enabled;
u64 runtime_expires;
s64 runtime_remaining;
int throttled;
struct list_head throttled_list;
#endif
#endif
};
@ -441,6 +446,7 @@ static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
cfs_b->quota = RUNTIME_INF;
cfs_b->period = ns_to_ktime(default_cfs_period());
INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cfs_b->period_timer.function = sched_cfs_period_timer;
}
@ -448,6 +454,7 @@ static void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
{
cfs_rq->runtime_enabled = 0;
INIT_LIST_HEAD(&cfs_rq->throttled_list);
}
/* requires cfs_b->lock, may release to reprogram timer */

89
kernel/sched_fair.c
View File

@ -1291,7 +1291,8 @@ static void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
}
static void assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
/* 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);
@ -1332,6 +1333,8 @@ static void assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
*/
if ((s64)(expires - cfs_rq->runtime_expires) > 0)
cfs_rq->runtime_expires = expires;
return cfs_rq->runtime_remaining > 0;
}
/*
@ -1378,7 +1381,12 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
if (likely(cfs_rq->runtime_remaining > 0))
return;
assign_cfs_rq_runtime(cfs_rq);
/*
* 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,
@ -1390,6 +1398,47 @@ static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
__account_cfs_rq_runtime(cfs_rq, delta_exec);
}
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
{
return cfs_rq->throttled;
}
static __used 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 */
update_cfs_load(cfs_rq, 0);
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;
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);
}
/*
* Responsible for refilling a task_group's bandwidth and unthrottling its
* cfs_rqs as appropriate. If there has been no activity within the last
@ -1425,6 +1474,11 @@ out_unlock:
#else
static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
unsigned long delta_exec) {}
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
{
return 0;
}
#endif
/**************************************************
@ -1503,7 +1557,17 @@ 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;
}
@ -1511,11 +1575,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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);
}
inc_nr_running(rq);
if (!se)
inc_nr_running(rq);
hrtick_update(rq);
}
@ -1535,6 +1603,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
for_each_sched_entity(se) {
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 */
@ -1557,11 +1634,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
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);
}
dec_nr_running(rq);
if (!se)
dec_nr_running(rq);
hrtick_update(rq);
}