Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756080Ab2FNNdU (ORCPT ); Thu, 14 Jun 2012 09:33:20 -0400 Received: from casper.infradead.org ([85.118.1.10]:53292 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753073Ab2FNNdR (ORCPT ); Thu, 14 Jun 2012 09:33:17 -0400 Message-Id: <20120614133212.690691207@chello.nl> User-Agent: quilt/0.48-1 Date: Thu, 14 Jun 2012 15:29:04 +0200 From: Peter Zijlstra To: mingo@kernel.org, pjt@google.com, venki@google.com, efault@gmx.de, rostedt@goodmis.org, glommer@parallels.com Cc: linux-kernel@vger.kernel.org, Peter Zijlstra Subject: [RFC][PATCH 2/4] sched: Push put_prev_task() into pick_next_task() References: <20120614132902.800827488@chello.nl> Content-Disposition: inline; filename=peter_zijlstra-sched-optimize_cgroup_pick_next_task_fair_2.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5216 Lines: 185 In order to avoid having to do put/set on a whole cgroup hierarchy when we context switch, push the put into pick_next_task() so that both operations are in the same function. Further changes then allow us to possibly optimize away redundant work. Signed-off-by: Peter Zijlstra --- include/linux/sched.h | 3 ++- kernel/sched/core.c | 13 +++++++------ kernel/sched/fair.c | 6 +++++- kernel/sched/idle_task.c | 6 +++++- kernel/sched/rt.c | 27 ++++++++++++++++----------- kernel/sched/stop_task.c | 9 +++++++-- 6 files changed, 42 insertions(+), 22 deletions(-) --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1093,7 +1093,8 @@ struct sched_class { void (*check_preempt_curr) (struct rq *rq, struct task_struct *p, int flags); - struct task_struct * (*pick_next_task) (struct rq *rq); + struct task_struct * (*pick_next_task) (struct rq *rq, + struct task_struct *prev); void (*put_prev_task) (struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3176,7 +3176,7 @@ static void put_prev_task(struct rq *rq, * Pick up the highest-prio task: */ static inline struct task_struct * -pick_next_task(struct rq *rq) +pick_next_task(struct rq *rq, struct task_struct *prev) { const struct sched_class *class; struct task_struct *p; @@ -3186,13 +3186,13 @@ pick_next_task(struct rq *rq) * the fair class we can call that function directly: */ if (likely(rq->nr_running == rq->cfs.h_nr_running)) { - p = fair_sched_class.pick_next_task(rq); + p = fair_sched_class.pick_next_task(rq, prev); if (likely(p)) return p; } for_each_class(class) { - p = class->pick_next_task(rq); + p = class->pick_next_task(rq, prev); if (p) return p; } @@ -3253,8 +3253,9 @@ static void __sched __schedule(void) if (unlikely(!rq->nr_running)) idle_balance(cpu, rq); - put_prev_task(rq, prev); - next = pick_next_task(rq); + if (prev->on_rq || rq->skip_clock_update < 0) + update_rq_clock(rq); + next = pick_next_task(rq, prev); clear_tsk_need_resched(prev); rq->skip_clock_update = 0; @@ -5200,7 +5201,7 @@ static void migrate_tasks(unsigned int d if (rq->nr_running == 1) break; - next = pick_next_task(rq); + next = pick_next_task(rq, NULL); BUG_ON(!next); next->sched_class->put_prev_task(rq, next); --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2990,7 +2990,8 @@ static void check_preempt_wakeup(struct set_last_buddy(se); } -static struct task_struct *pick_next_task_fair(struct rq *rq) +static struct task_struct * +pick_next_task_fair(struct rq *rq, struct task_struct *prev) { struct task_struct *p; struct cfs_rq *cfs_rq = &rq->cfs; @@ -2999,6 +3000,9 @@ static struct task_struct *pick_next_tas if (!cfs_rq->nr_running) return NULL; + if (prev) + prev->sched_class->put_prev_task(rq, prev); + do { se = pick_next_entity(cfs_rq); set_next_entity(cfs_rq, se); --- a/kernel/sched/idle_task.c +++ b/kernel/sched/idle_task.c @@ -22,8 +22,12 @@ static void check_preempt_curr_idle(stru resched_task(rq->idle); } -static struct task_struct *pick_next_task_idle(struct rq *rq) +static struct task_struct * +pick_next_task_idle(struct rq *rq, struct task_struct *prev) { + if (prev) + prev->sched_class->put_prev_task(rq, prev); + schedstat_inc(rq, sched_goidle); calc_load_account_idle(rq); return rq->idle; --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1346,15 +1346,7 @@ static struct task_struct *_pick_next_ta { struct sched_rt_entity *rt_se; struct task_struct *p; - struct rt_rq *rt_rq; - - rt_rq = &rq->rt; - - if (!rt_rq->rt_nr_running) - return NULL; - - if (rt_rq_throttled(rt_rq)) - return NULL; + struct rt_rq *rt_rq = &rq->rt; do { rt_se = pick_next_rt_entity(rq, rt_rq); @@ -1368,9 +1360,22 @@ static struct task_struct *_pick_next_ta return p; } -static struct task_struct *pick_next_task_rt(struct rq *rq) +static struct task_struct * +pick_next_task_rt(struct rq *rq, struct task_struct *prev) { - struct task_struct *p = _pick_next_task_rt(rq); + struct task_struct *p; + struct rt_rq *rt_rq = &rq->rt; + + if (!rt_rq->rt_nr_running) + return NULL; + + if (rt_rq_throttled(rt_rq)) + return NULL; + + if (prev) + prev->sched_class->put_prev_task(rq, prev); + + p = _pick_next_task_rt(rq); /* The running task is never eligible for pushing */ if (p) --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -23,12 +23,17 @@ check_preempt_curr_stop(struct rq *rq, s /* we're never preempted */ } -static struct task_struct *pick_next_task_stop(struct rq *rq) +static struct task_struct * +pick_next_task_stop(struct rq *rq, struct task_struct *prev) { struct task_struct *stop = rq->stop; - if (stop && stop->on_rq) + if (stop && stop->on_rq) { + if (prev) + prev->sched_class->put_prev_task(rq, prev); + return stop; + } return NULL; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/