On Thu, Jun 20, 2013 at 10:45:39PM +0200, Frederic Weisbecker wrote:
> Gather the common code that computes the pending idle cpu load
> to decay.
>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Li Zhong <[email protected]>
> Cc: Paul E. McKenney <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Alex Shi <[email protected]>
> Cc: Paul Turner <[email protected]>
> Cc: Mike Galbraith <[email protected]>
> Cc: Vincent Guittot <[email protected]>
> ---
> kernel/sched/proc.c | 40 ++++++++++++++--------------------------
> 1 files changed, 14 insertions(+), 26 deletions(-)
>
> diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c
> index bb3a6a0..030528a 100644
> --- a/kernel/sched/proc.c
> +++ b/kernel/sched/proc.c
> @@ -470,11 +470,14 @@ decay_load_missed(unsigned long load, unsigned long
> missed_updates, int idx)
> * scheduler tick (TICK_NSEC). With tickless idle this will not be called
> * every tick. We fix it up based on jiffies.
> */
> -static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
> - unsigned long pending_updates)
> +static void __update_cpu_load(struct rq *this_rq, unsigned long this_load)
> {
> + unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
Isn't jiffies declared volatile? (Looks that way to me.) If so, there
is no need for ACCESS_ONCE().
> + unsigned long pending_updates;
> int i, scale;
>
> + pending_updates = curr_jiffies - this_rq->last_load_update_tick;
> + this_rq->last_load_update_tick = curr_jiffies;
> this_rq->nr_load_updates++;
>
> /* Update our load: */
> @@ -521,20 +524,15 @@ static void __update_cpu_load(struct rq *this_rq,
> unsigned long this_load,
> */
> void update_idle_cpu_load(struct rq *this_rq)
> {
> - unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
> unsigned long load = this_rq->load.weight;
> - unsigned long pending_updates;
>
> /*
> * bail if there's load or we're actually up-to-date.
> */
> - if (load || curr_jiffies == this_rq->last_load_update_tick)
> + if (load || jiffies == this_rq->last_load_update_tick)
> return;
>
> - pending_updates = curr_jiffies - this_rq->last_load_update_tick;
> - this_rq->last_load_update_tick = curr_jiffies;
> -
> - __update_cpu_load(this_rq, load, pending_updates);
> + __update_cpu_load(this_rq, load);
> }
>
> /*
> @@ -543,22 +541,16 @@ void update_idle_cpu_load(struct rq *this_rq)
> void update_cpu_load_nohz(void)
> {
> struct rq *this_rq = this_rq();
> - unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
> - unsigned long pending_updates;
>
> - if (curr_jiffies == this_rq->last_load_update_tick)
> + if (jiffies == this_rq->last_load_update_tick)
> return;
>
> raw_spin_lock(&this_rq->lock);
> - pending_updates = curr_jiffies - this_rq->last_load_update_tick;
> - if (pending_updates) {
> - this_rq->last_load_update_tick = curr_jiffies;
> - /*
> - * We were idle, this means load 0, the current load might be
> - * !0 due to remote wakeups and the sort.
> - */
> - __update_cpu_load(this_rq, 0, pending_updates);
> - }
> + /*
> + * We were idle, this means load 0, the current load might be
> + * !0 due to remote wakeups and the sort.
> + */
> + __update_cpu_load(this_rq, 0);
> raw_spin_unlock(&this_rq->lock);
> }
> #endif /* CONFIG_NO_HZ */
> @@ -568,11 +560,7 @@ void update_cpu_load_nohz(void)
> */
> void update_cpu_load_active(struct rq *this_rq)
> {
> - /*
> - * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
> - */
> - this_rq->last_load_update_tick = jiffies;
> - __update_cpu_load(this_rq, this_rq->load.weight, 1);
> + __update_cpu_load(this_rq, this_rq->load.weight);
>
> calc_load_account_active(this_rq);
> }
> --
> 1.7.5.4
>
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