From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755694AbaICJvy (ORCPT ); Wed, 3 Sep 2014 05:51:54 -0400 Received: from casper.infradead.org ([85.118.1.10]:38986 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751573AbaICJvw (ORCPT ); Wed, 3 Sep 2014 05:51:52 -0400 Date: Wed, 3 Sep 2014 11:51:48 +0200 From: Peter Zijlstra To: Chuansheng Liu Cc: luto@amacapital.net, daniel.lezcano@linaro.org, rjw@rjwysocki.net, mingo@redhat.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, changcheng.liu@intel.com, xiaoming.wang@intel.com, souvik.k.chakravarty@intel.com Subject: Re: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the idle cpu Message-ID: <20140903095148.GH4783@worktop.ger.corp.intel.com> References: <1408351052-25075-1-git-send-email-chuansheng.liu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1408351052-25075-1-git-send-email-chuansheng.liu@intel.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 18, 2014 at 04:37:30PM +0800, Chuansheng Liu wrote: > 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 | 16 ++++++++++++++++ > 2 files changed, 17 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..adf104f 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1620,6 +1620,22 @@ 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 (set_nr_if_polling(rq->idle)) { > + trace_sched_wake_idle_without_ipi(cpu); > + } else { > + raw_spin_lock_irqsave(&rq->lock, flags); > + if (rq->curr == rq->idle) That needs to be is_idle_task(), there might be other 'idle' tasks than rq->idle :/ > + 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 >