On Mon, 2012-09-10 at 15:10 +0800, Alex Shi wrote:
> There is no load_balancer to be selected now. It just set state of
> nohz tick stopping.
>
> So rename the function, pass the 'cpu' from parameter and then
> remove the useless calling from tick_nohz_restart_sched_tick().
Please check who wrote the code you're patching and attempt to CC them
as well, in this case Venki and Suresh.
I think the patch is fine, although I think we could have picked a
better name, how about nohz_balance_enter_idle() ?
> Signed-off-by: Alex Shi <alex....@intel.com>
> ---
> include/linux/sched.h | 4 ++--
> kernel/sched/fair.c | 19 +++++++------------
> kernel/time/tick-sched.c | 3 +--
> 3 files changed, 10 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index b8c8664..5cba49c 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -273,11 +273,11 @@ extern void init_idle_bootup_task(struct task_struct
> *idle);
> extern int runqueue_is_locked(int cpu);
>
> #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
> -extern void select_nohz_load_balancer(int stop_tick);
> +extern void set_nohz_tick_stopped(int cpu);
> extern void set_cpu_sd_state_idle(void);
> extern int get_nohz_timer_target(void);
> #else
> -static inline void select_nohz_load_balancer(int stop_tick) { }
> +static inline void set_nohz_tick_stopped(int cpu) { }
> static inline void set_cpu_sd_state_idle(void) { }
> #endif
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index c219bf8..5bbc4bf 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4674,28 +4674,23 @@ void set_cpu_sd_state_idle(void)
> }
>
> /*
> - * This routine will record that this cpu is going idle with tick stopped.
> + * This routine will record that the cpu is going idle with tick stopped.
> * This info will be used in performing idle load balancing in the future.
> */
> -void select_nohz_load_balancer(int stop_tick)
> +void set_nohz_tick_stopped(int cpu)
> {
> - int cpu = smp_processor_id();
> -
> /*
> * If this cpu is going down, then nothing needs to be done.
> */
> if (!cpu_active(cpu))
> return;
>
> - if (stop_tick) {
> - if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
> - return;
> + if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
> + return;
>
> - cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
> - atomic_inc(&nohz.nr_cpus);
> - set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
> - }
> - return;
> + cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
> + atomic_inc(&nohz.nr_cpus);
> + set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
> }
>
> static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 024540f..eacde97 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -372,7 +372,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct
> tick_sched *ts,
> * the scheduler tick in nohz_restart_sched_tick.
> */
> if (!ts->tick_stopped) {
> - select_nohz_load_balancer(1);
> + set_nohz_tick_stopped(cpu);
> calc_load_enter_idle();
>
> ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
> @@ -569,7 +569,6 @@ static void tick_nohz_restart(struct tick_sched *ts,
> ktime_t now)
> static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
> {
> /* Update jiffies first */
> - select_nohz_load_balancer(0);
> tick_do_update_jiffies64(now);
> update_cpu_load_nohz();
>
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