Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751851AbaBKPLz (ORCPT ); Tue, 11 Feb 2014 10:11:55 -0500 Received: from merlin.infradead.org ([205.233.59.134]:57406 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751783AbaBKPLx (ORCPT ); Tue, 11 Feb 2014 10:11:53 -0500 Date: Tue, 11 Feb 2014 16:11:48 +0100 From: Peter Zijlstra To: Daniel Lezcano Cc: mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/fair: Remove idle_balance() declaration in sched.h Message-ID: <20140211151148.GP27965@twins.programming.kicks-ass.net> References: <1392130864-4416-1-git-send-email-daniel.lezcano@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1392130864-4416-1-git-send-email-daniel.lezcano@linaro.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 11, 2014 at 04:01:04PM +0100, Daniel Lezcano wrote: > The idle_balance() function is called within a #ifdef CONFIG_SMP section. > > Remove its declaration in sched.h for !CONFIG_SMP because it is pointless. > > Signed-off-by: Daniel Lezcano The below again makes a horrible mess of idle_balance() -- which you tried to clean up.. but it does rid us of some #ifdef goo. Hmmm? --- kernel/sched/fair.c | 47 +++++++++++++++++++++++++++++------------------ kernel/sched/sched.h | 7 ------- 2 files changed, 29 insertions(+), 25 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 235cfa7ad8fc..d168c968195b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2374,13 +2374,13 @@ static inline void __update_group_entity_contrib(struct sched_entity *se) se->avg.load_avg_contrib >>= NICE_0_SHIFT; } } -#else +#else /* CONFIG_FAIR_GROUP_SCHED */ static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, int force_update) {} static inline void __update_tg_runnable_avg(struct sched_avg *sa, struct cfs_rq *cfs_rq) {} static inline void __update_group_entity_contrib(struct sched_entity *se) {} -#endif +#endif /* CONFIG_FAIR_GROUP_SCHED */ static inline void __update_task_entity_contrib(struct sched_entity *se) { @@ -2571,6 +2571,8 @@ void idle_exit_fair(struct rq *this_rq) update_rq_runnable_avg(this_rq, 0); } +static int idle_balance(struct rq *this_rq); + #else /* CONFIG_SMP */ static inline void update_entity_load_avg(struct sched_entity *se, @@ -2584,6 +2586,12 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, int sleep) {} static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) {} + +static inline int idle_balance(struct rq *rq) +{ + return 0; +} + #endif /* CONFIG_SMP */ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) @@ -4677,7 +4685,7 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev) struct sched_entity *se; struct task_struct *p; -again: __maybe_unused +again: #ifdef CONFIG_FAIR_GROUP_SCHED if (!cfs_rq->nr_running) goto idle; @@ -4775,18 +4783,8 @@ again: __maybe_unused return p; idle: -#ifdef CONFIG_SMP - idle_enter_fair(rq); - /* - * We must set idle_stamp _before_ calling idle_balance(), such that we - * measure the duration of idle_balance() as idle time. - */ - rq->idle_stamp = rq_clock(rq); - if (idle_balance(rq)) { /* drops rq->lock */ - rq->idle_stamp = 0; + if (idle_balance(rq)) /* drops rq->lock */ goto again; - } -#endif return NULL; } @@ -6634,7 +6632,7 @@ static int load_balance(int this_cpu, struct rq *this_rq, * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ -int idle_balance(struct rq *this_rq) +static int idle_balance(struct rq *this_rq) { struct sched_domain *sd; int pulled_task = 0; @@ -6642,8 +6640,15 @@ int idle_balance(struct rq *this_rq) u64 curr_cost = 0; int this_cpu = this_rq->cpu; + idle_enter_fair(this_rq); + /* + * We must set idle_stamp _before_ calling idle_balance(), such that we + * measure the duration of idle_balance() as idle time. + */ + this_rq->idle_stamp = rq_clock(this_rq); + if (this_rq->avg_idle < sysctl_sched_migration_cost) - return 0; + goto out; /* * Drop the rq->lock, but keep IRQ/preempt disabled. @@ -6692,8 +6697,10 @@ int idle_balance(struct rq *this_rq) * While browsing the domains, we released the rq lock. * A task could have be enqueued in the meantime */ - if (this_rq->nr_running && !pulled_task) - return 1; + if (this_rq->nr_running && !pulled_task) { + pulled_task = 1; + goto out; + } if (pulled_task || time_after(jiffies, this_rq->next_balance)) { /* @@ -6706,6 +6713,10 @@ int idle_balance(struct rq *this_rq) if (curr_cost > this_rq->max_idle_balance_cost) this_rq->max_idle_balance_cost = curr_cost; +out: + if (pulled_task) + this_rq->idle_stamp = 0; + return pulled_task; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1bf34c257d3b..92018f9821e8 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1163,17 +1163,10 @@ extern const struct sched_class idle_sched_class; extern void update_group_power(struct sched_domain *sd, int cpu); extern void trigger_load_balance(struct rq *rq); -extern int idle_balance(struct rq *this_rq); extern void idle_enter_fair(struct rq *this_rq); extern void idle_exit_fair(struct rq *this_rq); -#else /* CONFIG_SMP */ - -static inline void idle_balance(int cpu, struct rq *rq) -{ -} - #endif extern void sysrq_sched_debug_show(void); -- 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/