On Fri, Sep 19, 2014 at 4:43 AM, tip-bot for Chuansheng Liu
<tipbot@xxxxxxxxx> wrote:
> Commit-ID: f6be8af1c95de4a46e325e728900a70ceadb52cf
> Gitweb: http://git.kernel.org/tip/f6be8af1c95de4a46e325e728900a70ceadb52cf
> Author: Chuansheng Liu <chuansheng.liu@xxxxxxxxx>
> AuthorDate: Thu, 4 Sep 2014 15:17:53 +0800
> Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Fri, 19 Sep 2014 12:35:14 +0200
>
> sched: Add new API wake_up_if_idle() to wake up the idle cpu
>
> Implementing one new API wake_up_if_idle(), which is used to
> wake up the idle CPU.
>
> Suggested-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Signed-off-by: Chuansheng Liu <chuansheng.liu@xxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Cc: daniel.lezcano@xxxxxxxxxx
> Cc: rjw@xxxxxxxxxxxxx
> Cc: linux-pm@xxxxxxxxxxxxxxx
> Cc: changcheng.liu@xxxxxxxxx
> Cc: xiaoming.wang@xxxxxxxxx
> Cc: souvik.k.chakravarty@xxxxxxxxx
> Cc: chuansheng.liu@xxxxxxxxx
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Link: http://lkml.kernel.org/r/1409815075-4180-1-git-send-email-chuansheng.liu@xxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
> 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 dd9eb48..82ff3d6 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 78e5c83..f7c6ed2 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1634,6 +1634,25 @@ 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))
This is old news, but why isn't this if (rq->curr != rq->idle)?
--Andy
> + 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);
--
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