From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933788AbYETPWj (ORCPT ); Tue, 20 May 2008 11:22:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933665AbYETPVw (ORCPT ); Tue, 20 May 2008 11:21:52 -0400 Received: from 66-189-124-104.dhcp.oxfr.ma.charter.com ([66.189.124.104]:57736 "EHLO novell1.haskins.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933404AbYETPVu (ORCPT ); Tue, 20 May 2008 11:21:50 -0400 From: Gregory Haskins Subject: [PATCH 2/5] sched: make task->oncpu available in all configurations To: mingo@elte.hu, tglx@linutronix.de, rostedt@goodmis.org, linux-rt-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, sdietrich@novell.com, pmorreale@novell.com, mkohari@novell.com, ghaskins@novell.com Date: Tue, 20 May 2008 10:49:20 -0400 Message-ID: <20080520144920.15992.40920.stgit@novell1.haskins.net> In-Reply-To: <20080520143954.15992.85900.stgit@novell1.haskins.net> References: <20080520143954.15992.85900.stgit@novell1.haskins.net> User-Agent: StGIT/0.12.1 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 We will use this later in the series to eliminate the need for a function call. Signed-off-by: Gregory Haskins --- include/linux/sched.h | 2 -- kernel/sched.c | 35 ++++++++++++++++++++++++----------- 2 files changed, 24 insertions(+), 13 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index ec94970..70175e0 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1080,10 +1080,8 @@ struct task_struct { int lock_depth; /* BKL lock depth */ #ifdef CONFIG_SMP -#ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif -#endif int prio, static_prio, normal_prio; #ifdef CONFIG_PREEMPT_RCU_BOOST diff --git a/kernel/sched.c b/kernel/sched.c index 4428916..03cb222 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -699,18 +699,39 @@ static inline int task_current(struct rq *rq, struct task_struct *p) return rq->curr == p; } -#ifndef __ARCH_WANT_UNLOCKED_CTXSW static inline int task_running(struct rq *rq, struct task_struct *p) { +#ifdef CONFIG_SMP + return p->oncpu; +#else return task_current(rq, p); +#endif } +#ifndef __ARCH_WANT_UNLOCKED_CTXSW static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) { +#ifdef CONFIG_SMP + /* + * We can optimise this out completely for !SMP, because the + * SMP rebalancing from interrupt is the only thing that cares + * here. + */ + next->oncpu = 1; +#endif } static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) { +#ifdef CONFIG_SMP + /* + * After ->oncpu is cleared, the task can be moved to a different CPU. + * We must ensure this doesn't happen until the switch is completely + * finished. + */ + smp_wmb(); + prev->oncpu = 0; +#endif #ifdef CONFIG_DEBUG_SPINLOCK /* this is a valid case when another task releases the spinlock */ rq->lock.owner = current; @@ -726,14 +747,6 @@ static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev) } #else /* __ARCH_WANT_UNLOCKED_CTXSW */ -static inline int task_running(struct rq *rq, struct task_struct *p) -{ -#ifdef CONFIG_SMP - return p->oncpu; -#else - return task_current(rq, p); -#endif -} static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next) { @@ -2082,7 +2095,7 @@ void sched_fork(struct task_struct *p, int clone_flags) if (likely(sched_info_on())) memset(&p->sched_info, 0, sizeof(p->sched_info)); #endif -#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) +#if defined(CONFIG_SMP) p->oncpu = 0; #endif #ifdef CONFIG_PREEMPT @@ -5684,7 +5697,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu) spin_lock_irqsave(&rq->lock, flags); rq->curr = rq->idle = idle; -#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) +#if defined(CONFIG_SMP) idle->oncpu = 1; #endif spin_unlock_irqrestore(&rq->lock, flags);