From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932319AbaIDHdn (ORCPT ); Thu, 4 Sep 2014 03:33:43 -0400 Received: from mga14.intel.com ([192.55.52.115]:53400 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756164AbaIDHdm (ORCPT ); Thu, 4 Sep 2014 03:33:42 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="381246196" From: Chuansheng Liu To: peterz@infradead.org, luto@amacapital.net, daniel.lezcano@linaro.org, rjw@rjwysocki.net, mingo@redhat.com Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, changcheng.liu@intel.com, xiaoming.wang@intel.com, souvik.k.chakravarty@intel.com, chuansheng.liu@intel.com Subject: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the idle cpu Date: Thu, 4 Sep 2014 15:17:53 +0800 Message-Id: <1409815075-4180-1-git-send-email-chuansheng.liu@intel.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Implementing one new API wake_up_if_idle(), which is used to wake up the idle CPU. Suggested-by: Andy Lutomirski Signed-off-by: Chuansheng Liu --- include/linux/sched.h | 1 + kernel/sched/core.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index 857ba40..3f89ac1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1024,6 +1024,7 @@ struct sched_domain_topology_level { extern struct sched_domain_topology_level *sched_domain_topology; extern void set_sched_topology(struct sched_domain_topology_level *tl); +extern void wake_up_if_idle(int cpu); #ifdef CONFIG_SCHED_DEBUG # define SD_INIT_NAME(type) .name = #type diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 1211575..b818548 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1620,6 +1620,25 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu) } } +void wake_up_if_idle(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + + if (!is_idle_task(rq->curr)) + return; + + if (set_nr_if_polling(rq->idle)) { + trace_sched_wake_idle_without_ipi(cpu); + } else { + raw_spin_lock_irqsave(&rq->lock, flags); + if (is_idle_task(rq->curr)) + smp_send_reschedule(cpu); + /* Else cpu is not in idle, do nothing here */ + raw_spin_unlock_irqrestore(&rq->lock, flags); + } +} + bool cpus_share_cache(int this_cpu, int that_cpu) { return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); -- 1.7.9.5