From d3d9dc3302368269acf94b7381663b93000fe2fe Mon Sep 17 00:00:00 2001 From: Paul Turner Date: Thu, 21 Jul 2011 09:43:39 -0700 Subject: [PATCH] sched: Throttle entities exceeding their allowed bandwidth With the machinery in place to throttle and unthrottle entities, as well as handle their participation (or lack there of) we can now enable throttling. There are 2 points that we must check whether it's time to set throttled state: put_prev_entity() and enqueue_entity(). - put_prev_entity() is the typical throttle path, we reach it by exceeding our allocated run-time within update_curr()->account_cfs_rq_runtime() and going through a reschedule. - enqueue_entity() covers the case of a wake-up into an already throttled group. In this case we know the group cannot be on_rq and can throttle immediately. Checks are added at time of put_prev_entity() and enqueue_entity() Signed-off-by: Paul Turner Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20110721184758.091415417@google.com Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 52 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 50 insertions(+), 2 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 1d4acbea9e60..f9f671a7d0af 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -970,6 +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) { @@ -999,8 +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) @@ -1202,6 +1206,8 @@ 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) { /* @@ -1211,6 +1217,9 @@ 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); @@ -1464,7 +1473,7 @@ static int tg_throttle_down(struct task_group *tg, void *data) return 0; } -static __used void throttle_cfs_rq(struct cfs_rq *cfs_rq) +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); @@ -1657,9 +1666,48 @@ out_unlock: return idle; } + +/* + * 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 inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) { -- 2.20.1