On Tue, Mar 18, 2014 at 04:26:07PM +0530, Viresh Kumar wrote:
> There are only two users of get_nohz_timer_target(): timer and hrtimer. Both
> call it under same circumstances, i.e.
>
> #ifdef CONFIG_NO_HZ_COMMON
> if (!pinned && get_sysctl_timer_migration() &&
> idle_cpu(this_cpu))
> return get_nohz_timer_target();
> #endif
>
> So, it makes more sense to get all this as part of get_nohz_timer_target()
> instead of duplicating code at two places. For this another parameter is
> required to be passed to this routine, pinned.
>
> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
> ---
> include/linux/sched.h | 6 +++++-
> kernel/hrtimer.c | 15 +--------------
> kernel/sched/core.c | 5 ++++-
> kernel/timer.c | 7 +------
> 4 files changed, 11 insertions(+), 22 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 6dbb9e5..9819f93 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -299,10 +299,14 @@ extern int runqueue_is_locked(int cpu);
> #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
> extern void nohz_balance_enter_idle(int cpu);
> extern void set_cpu_sd_state_idle(void);
> -extern int get_nohz_timer_target(void);
> +extern int get_nohz_timer_target(int pinned);
> #else
> static inline void nohz_balance_enter_idle(int cpu) { }
> static inline void set_cpu_sd_state_idle(void) { }
> +static inline int get_nohz_timer_target(int pinned)
> +{
> + return smp_processor_id();
> +}
> #endif
>
> /*
> diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
> index f60dce8..7eef615 100644
> --- a/kernel/hrtimer.c
> +++ b/kernel/hrtimer.c
> @@ -168,19 +168,6 @@ struct hrtimer_clock_base *lock_hrtimer_base(const
> struct hrtimer *timer,
> }
> }
>
> -
> -/*
> - * Get the preferred target CPU for NOHZ
> - */
> -static int hrtimer_get_target(int this_cpu, int pinned)
> -{
> -#ifdef CONFIG_NO_HZ_COMMON
> - if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu))
> - return get_nohz_timer_target();
> -#endif
> - return this_cpu;
> -}
> -
> /*
> * With HIGHRES=y we do not migrate the timer when it is expiring
> * before the next event on the target cpu because we cannot reprogram
> @@ -214,7 +201,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct
> hrtimer_clock_base *base,
> struct hrtimer_clock_base *new_base;
> struct hrtimer_cpu_base *new_cpu_base;
> int this_cpu = smp_processor_id();
> - int cpu = hrtimer_get_target(this_cpu, pinned);
> + int cpu = get_nohz_timer_target(pinned);
> int basenum = base->index;
>
> again:
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 6fde755..a58e24d 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -556,12 +556,15 @@ void resched_cpu(int cpu)
> * selecting an idle cpu will add more delays to the timers than intended
> * (as that cpu's timer base may not be uptodate wrt jiffies etc).
> */
> -int get_nohz_timer_target(void)
> +int get_nohz_timer_target(int pinned)
> {
> int cpu = smp_processor_id();
> int i;
> struct sched_domain *sd;
>
> + if (pinned || !get_sysctl_timer_migration() || !idle_cpu(cpu))
> + return cpu;
Maybe the pinned part should stay a caller detail. Although I don't really mind.
The patch looks good!
Thanks.
> +
> rcu_read_lock();
> for_each_domain(cpu, sd) {
> for_each_cpu(i, sched_domain_span(sd)) {
> diff --git a/kernel/timer.c b/kernel/timer.c
> index e6868bf..2cf8616 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -760,12 +760,7 @@ __mod_timer(struct timer_list *timer, unsigned long
> expires,
>
> debug_activate(timer, expires);
>
> - cpu = smp_processor_id();
> -
> -#if defined(CONFIG_NO_HZ_COMMON) && defined(CONFIG_SMP)
> - if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
> - cpu = get_nohz_timer_target();
> -#endif
> + cpu = get_nohz_timer_target(pinned);
> new_base = per_cpu(tvec_bases, cpu);
>
> if (base != new_base) {
> --
> 1.7.12.rc2.18.g61b472e
>
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