Re: [RFC PATCH] rcu: move SRCU grace period work to power efficient workqueue

[Zoran Markovic <zoran.markovic@linaro.org>]

Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>

On 31 January 2014 11:53, Zoran Markovic <zoran.markovic@linaro.org> wrote:
> From: Shaibal Dutta <shaibal.dutta@broadcom.com>
>
> For better use of CPU idle time, allow the scheduler to select the CPU
> on which the SRCU grace period work would be scheduled. This improves
> idle residency time and conserves power.
>
> This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.
>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
> Cc: Dipankar Sarma <dipankar@in.ibm.com>
> Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com>
> [zoran.markovic@linaro.org: Rebased to latest kernel version. Added commit
> message. Fixed code alignment.]
> ---
>  kernel/rcu/srcu.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
> index 3318d82..a1ebe6d 100644
> --- a/kernel/rcu/srcu.c
> +++ b/kernel/rcu/srcu.c
> @@ -398,7 +398,7 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
>         rcu_batch_queue(&sp->batch_queue, head);
>         if (!sp->running) {
>                 sp->running = true;
> -               schedule_delayed_work(&sp->work, 0);
> +               queue_delayed_work(system_power_efficient_wq, &sp->work, 0);
>         }
>         spin_unlock_irqrestore(&sp->queue_lock, flags);
>  }
> @@ -674,7 +674,8 @@ static void srcu_reschedule(struct srcu_struct *sp)
>         }
>
>         if (pending)
> -               schedule_delayed_work(&sp->work, SRCU_INTERVAL);
> +               queue_delayed_work(system_power_efficient_wq,
> +                                  &sp->work, SRCU_INTERVAL);
>  }
>
>  /*
> --
> 1.7.9.5
>