From 48a1675323fa1b7844e479ad2a4469f4558c0f79 Mon Sep 17 00:00:00 2001 From: Paul Turner Date: Thu, 4 Oct 2012 13:18:31 +0200 Subject: sched: Refactor update_shares_cpu() -> update_blocked_avgs() Now that running entities maintain their own load-averages the work we must do in update_shares() is largely restricted to the periodic decay of blocked entities. This allows us to be a little less pessimistic regarding our occupancy on rq->lock and the associated rq->clock updates required. Signed-off-by: Paul Turner Reviewed-by: Ben Segall Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20120823141507.133999170@google.com Signed-off-by: Ingo Molnar diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 57fae95..dcc27d8 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3639,20 +3639,15 @@ next: /* * update tg->load_weight by folding this cpu's load_avg */ -static int update_shares_cpu(struct task_group *tg, int cpu) +static void __update_blocked_averages_cpu(struct task_group *tg, int cpu) { - struct sched_entity *se; - struct cfs_rq *cfs_rq; - unsigned long flags; - struct rq *rq; - - rq = cpu_rq(cpu); - se = tg->se[cpu]; - cfs_rq = tg->cfs_rq[cpu]; + struct sched_entity *se = tg->se[cpu]; + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu]; - raw_spin_lock_irqsave(&rq->lock, flags); + /* throttled entities do not contribute to load */ + if (throttled_hierarchy(cfs_rq)) + return; - update_rq_clock(rq); update_cfs_rq_blocked_load(cfs_rq, 1); if (se) { @@ -3669,32 +3664,33 @@ static int update_shares_cpu(struct task_group *tg, int cpu) if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running) list_del_leaf_cfs_rq(cfs_rq); } else { + struct rq *rq = rq_of(cfs_rq); update_rq_runnable_avg(rq, rq->nr_running); } - - raw_spin_unlock_irqrestore(&rq->lock, flags); - - return 0; } -static void update_shares(int cpu) +static void update_blocked_averages(int cpu) { - struct cfs_rq *cfs_rq; struct rq *rq = cpu_rq(cpu); + struct cfs_rq *cfs_rq; + unsigned long flags; - rcu_read_lock(); + raw_spin_lock_irqsave(&rq->lock, flags); + update_rq_clock(rq); /* * Iterates the task_group tree in a bottom up fashion, see * list_add_leaf_cfs_rq() for details. */ for_each_leaf_cfs_rq(rq, cfs_rq) { - /* throttled entities do not contribute to load */ - if (throttled_hierarchy(cfs_rq)) - continue; - - update_shares_cpu(cfs_rq->tg, cpu); + /* + * Note: We may want to consider periodically releasing + * rq->lock about these updates so that creating many task + * groups does not result in continually extending hold time. + */ + __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); } - rcu_read_unlock(); + + raw_spin_unlock_irqrestore(&rq->lock, flags); } /* @@ -3746,7 +3742,7 @@ static unsigned long task_h_load(struct task_struct *p) return load; } #else -static inline void update_shares(int cpu) +static inline void update_blocked_averages(int cpu) { } @@ -4813,7 +4809,7 @@ void idle_balance(int this_cpu, struct rq *this_rq) */ raw_spin_unlock(&this_rq->lock); - update_shares(this_cpu); + update_blocked_averages(this_cpu); rcu_read_lock(); for_each_domain(this_cpu, sd) { unsigned long interval; @@ -5068,7 +5064,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle) int update_next_balance = 0; int need_serialize; - update_shares(cpu); + update_blocked_averages(cpu); rcu_read_lock(); for_each_domain(cpu, sd) { -- cgit v0.10.2