Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965334AbWKNMXQ (ORCPT ); Tue, 14 Nov 2006 07:23:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965335AbWKNMXQ (ORCPT ); Tue, 14 Nov 2006 07:23:16 -0500 Received: from ausmtp04.au.ibm.com ([202.81.18.152]:49882 "EHLO ausmtp04.au.ibm.com") by vger.kernel.org with ESMTP id S965334AbWKNMXP (ORCPT ); Tue, 14 Nov 2006 07:23:15 -0500 Date: Tue, 14 Nov 2006 17:53:25 +0530 From: Gautham R Shenoy To: Gautham R Shenoy Cc: akpm@osdl.org, torvalds@osdl.org, linux-kernel@vger.kernel.org, vatsa@in.ibm.com, dipankar@in.ibm.com, davej@redhat.com, mingo@elte.hu, kiran@scalex86.org Subject: [PATCH 3/4] Eliminate lock_cpu_hotplug in kernel/sched.c Message-ID: <20061114122325.GD31787@in.ibm.com> Reply-To: ego@in.ibm.com References: <20061114121832.GA31787@in.ibm.com> <20061114122050.GB31787@in.ibm.com> <20061114122214.GC31787@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061114122214.GC31787@in.ibm.com> User-Agent: Mutt/1.5.10i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3828 Lines: 138 Eliminate lock_cpu_hotplug from kernel/sched.c and use sched_hotcpu_mutex instead to postpone a hotplug event. In the migration_call hotcpu callback function, take sched_hotcpu_mutex while handling the event CPU_LOCK_ACQUIRE and release it while handling CPU_LOCK_RELEASE event. Signed-off-by: Gautham R Shenoy -- kernel/sched.c | 29 +++++++++++++++++++---------- 1 files changed, 19 insertions(+), 10 deletions(-) Index: hotplug/kernel/sched.c =================================================================== --- hotplug.orig/kernel/sched.c +++ hotplug/kernel/sched.c @@ -267,6 +267,7 @@ struct rq { }; static DEFINE_PER_CPU(struct rq, runqueues); +static DEFINE_MUTEX(sched_hotcpu_mutex); static inline int cpu_of(struct rq *rq) { @@ -4327,13 +4328,13 @@ long sched_setaffinity(pid_t pid, cpumas struct task_struct *p; int retval; - lock_cpu_hotplug(); + mutex_lock(&sched_hotcpu_mutex); read_lock(&tasklist_lock); p = find_process_by_pid(pid); if (!p) { read_unlock(&tasklist_lock); - unlock_cpu_hotplug(); + mutex_unlock(&sched_hotcpu_mutex); return -ESRCH; } @@ -4360,7 +4361,7 @@ long sched_setaffinity(pid_t pid, cpumas out_unlock: put_task_struct(p); - unlock_cpu_hotplug(); + mutex_unlock(&sched_hotcpu_mutex); return retval; } @@ -4417,7 +4418,7 @@ long sched_getaffinity(pid_t pid, cpumas struct task_struct *p; int retval; - lock_cpu_hotplug(); + mutex_lock(&sched_hotcpu_mutex); read_lock(&tasklist_lock); retval = -ESRCH; @@ -4433,7 +4434,7 @@ long sched_getaffinity(pid_t pid, cpumas out_unlock: read_unlock(&tasklist_lock); - unlock_cpu_hotplug(); + mutex_unlock(&sched_hotcpu_mutex); if (retval) return retval; @@ -5225,6 +5226,10 @@ migration_call(struct notifier_block *nf struct rq *rq; switch (action) { + case CPU_LOCK_ACQUIRE: + mutex_lock(&sched_hotcpu_mutex); + break; + case CPU_UP_PREPARE: p = kthread_create(migration_thread, hcpu, "migration/%d",cpu); if (IS_ERR(p)) @@ -5270,7 +5275,7 @@ migration_call(struct notifier_block *nf BUG_ON(rq->nr_running != 0); /* No need to migrate the tasks: it was best-effort if - * they didn't do lock_cpu_hotplug(). Just wake up + * they didn't take sched_hotcpu_mutex. Just wake up * the requestors. */ spin_lock_irq(&rq->lock); while (!list_empty(&rq->migration_queue)) { @@ -5283,6 +5288,10 @@ migration_call(struct notifier_block *nf } spin_unlock_irq(&rq->lock); break; + + case CPU_LOCK_RELEASE: + mutex_unlock(&sched_hotcpu_mutex); + break; #endif } return NOTIFY_OK; @@ -6652,10 +6661,10 @@ int arch_reinit_sched_domains(void) { int err; - lock_cpu_hotplug(); + mutex_lock(&sched_hotcpu_mutex); detach_destroy_domains(&cpu_online_map); err = arch_init_sched_domains(&cpu_online_map); - unlock_cpu_hotplug(); + mutex_unlock(&sched_hotcpu_mutex); return err; } @@ -6763,12 +6772,12 @@ void __init sched_init_smp(void) { cpumask_t non_isolated_cpus; - lock_cpu_hotplug(); + mutex_lock(&sched_hotcpu_mutex); arch_init_sched_domains(&cpu_online_map); cpus_andnot(non_isolated_cpus, cpu_online_map, cpu_isolated_map); if (cpus_empty(non_isolated_cpus)) cpu_set(smp_processor_id(), non_isolated_cpus); - unlock_cpu_hotplug(); + mutex_unlock(&sched_hotcpu_mutex); /* XXX: Theoretical race here - CPU may be hotplugged now */ hotcpu_notifier(update_sched_domains, 0); -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!" - 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/