From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758263Ab2F1C4u (ORCPT ); Wed, 27 Jun 2012 22:56:50 -0400 Received: from mail-wi0-f202.google.com ([209.85.212.202]:56518 "EHLO mail-wi0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758170Ab2F1C41 (ORCPT ); Wed, 27 Jun 2012 22:56:27 -0400 Subject: [PATCH 12/16] sched: refactor update_shares_cpu() -> update_blocked_avgs() To: linux-kernel@vger.kernel.org From: Paul Turner Cc: Venki Pallipadi , Srivatsa Vaddagiri , Vincent Guittot , Peter Zijlstra , Nikunj A Dadhania , Mike Galbraith , Kamalesh Babulal , Ben Segall , Ingo Molnar , "Paul E. McKenney" , Morten Rasmussen , Vaidyanathan Srinivasan Date: Wed, 27 Jun 2012 19:24:15 -0700 Message-ID: <20120628022415.30496.57167.stgit@kitami.mtv.corp.google.com> In-Reply-To: <20120628022413.30496.32798.stgit@kitami.mtv.corp.google.com> References: <20120628022413.30496.32798.stgit@kitami.mtv.corp.google.com> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- kernel/sched/fair.c | 59 +++++++++++++++++++++++++++++---------------------- 1 files changed, 33 insertions(+), 26 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4a9a828..dd1ef8a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3678,23 +3678,20 @@ out: /* * 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); - update_entity_load_avg(tg->se[cpu], 1); + if (se) + update_entity_load_avg(se, 1); + else + update_rq_runnable_avg(rq_of(cfs_rq), 1); if (se) { /* @@ -3707,29 +3704,39 @@ static int update_shares_cpu(struct task_group *tg, int cpu) else list_del_leaf_cfs_rq(cfs_rq); } - - 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; + int num_updates = 0; 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_blocked_averages_cpu(cfs_rq->tg, rq->cpu); - update_shares_cpu(cfs_rq->tg, cpu); + /* + * Periodically release the lock so that a cfs_rq with many + * children cannot hold it for an arbitrary period of time. + */ + if (num_updates++ % 20 == 0) { + raw_spin_unlock_irqrestore(&rq->lock, flags); + cpu_relax(); + raw_spin_lock_irqsave(&rq->lock, flags); + update_rq_clock(rq); + } } + + raw_spin_unlock_irqrestore(&rq->lock, flags); rcu_read_unlock(); } @@ -3774,7 +3781,7 @@ 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) { } @@ -4936,7 +4943,7 @@ 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; @@ -5196,7 +5203,7 @@ 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) {