From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chuansheng Liu Subject: [PATCH 1/3] sched: Add new API wake_up_if_idle() to wake up the idle cpu Date: Mon, 18 Aug 2014 16:37:30 +0800 Message-ID: <1408351052-25075-1-git-send-email-chuansheng.liu@intel.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: luto@amacapital.net, peterz@infradead.org, 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 List-Id: linux-pm@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 | 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) + 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