On Tue, Nov 10, 2015 at 09:36:02AM +0900, byungchul.p...@lge.com wrote:
> From: Byungchul Park <byungchul.p...@lge.com>
>
> Usually tick can be stopped for an idle cpu in NOHZ. However in NOHZ_FULL,
> a non-idle cpu's tick also can be stopped. However, update_cpu_load_nohz()
> does not consider the case a non-idle cpu's tick has been stopped at all.
>
> This patch makes the update_cpu_load_nohz() know if the calling path comes
> from NOHZ_FULL or idle NOHZ.
>
> Signed-off-by: Byungchul Park <byungchul.p...@lge.com>
> Acked-by: Frederic Weisbecker <fweis...@gmail.com>
> ---
> include/linux/sched.h | 4 ++--
> kernel/sched/fair.c | 10 ++++++----
> kernel/time/tick-sched.c | 8 ++++----
> 3 files changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 699228b..f1b59aa 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -177,9 +177,9 @@ extern void get_iowait_load(unsigned long *nr_waiters,
> unsigned long *load);
> extern void calc_global_load(unsigned long ticks);
>
> #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
> -extern void update_cpu_load_nohz(void);
> +extern void update_cpu_load_nohz(int active);
> #else
> -static inline void update_cpu_load_nohz(void) { }
> +static inline void update_cpu_load_nohz(int active) { }
> #endif
>
> extern unsigned long get_parent_ip(unsigned long addr);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7760678..3d93756 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4419,10 +4419,11 @@ static void update_idle_cpu_load(struct rq *this_rq)
> /*
> * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
> */
> -void update_cpu_load_nohz(void)
> +void update_cpu_load_nohz(int active)
> {
> struct rq *this_rq = this_rq();
> unsigned long curr_jiffies = READ_ONCE(jiffies);
> + unsigned long load = active ? weighted_cpuload(cpu_of(this_rq)) : 0;
Hello,
I added this part after you acked.. What do you think about this
modification?
> unsigned long pending_updates;
>
> if (curr_jiffies == this_rq->last_load_update_tick)
> @@ -4433,10 +4434,11 @@ void update_cpu_load_nohz(void)
> 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.
> + * In the regular NOHZ case, we were idle, this means load 0.
> + * In the NOHZ_FULL case, we were non-idle, we should consider
> + * its weighted load.
This, too.
> */
> - __update_cpu_load(this_rq, 0, pending_updates, 0);
> + __update_cpu_load(this_rq, load, pending_updates, active);
This, too.
Thank you,
byungchul
> }
> raw_spin_unlock(&this_rq->lock);
> }
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 7c7ec45..515edf3 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -694,11 +694,11 @@ out:
> return tick;
> }
>
> -static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
> +static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now,
> int active)
> {
> /* Update jiffies first */
> tick_do_update_jiffies64(now);
> - update_cpu_load_nohz();
> + update_cpu_load_nohz(active);
>
> calc_load_exit_idle();
> touch_softlockup_watchdog();
> @@ -725,7 +725,7 @@ static void tick_nohz_full_update_tick(struct tick_sched
> *ts)
> if (can_stop_full_tick())
> tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
> else if (ts->tick_stopped)
> - tick_nohz_restart_sched_tick(ts, ktime_get());
> + tick_nohz_restart_sched_tick(ts, ktime_get(), 1);
> #endif
> }
>
> @@ -916,7 +916,7 @@ void tick_nohz_idle_exit(void)
> tick_nohz_stop_idle(ts, now);
>
> if (ts->tick_stopped) {
> - tick_nohz_restart_sched_tick(ts, now);
> + tick_nohz_restart_sched_tick(ts, now, 0);
> tick_nohz_account_idle_ticks(ts);
> }
>
> --
> 1.7.9.5
>
> --
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