Re: [PATCH 1/6] cpufreq: schedutil: reset sg_cpus's flags at IDLE enter

Viresh Kumar
2017-03-03T07:38:27Z

On 02-03-17, 15:45, Patrick Bellasi wrote:
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index e2ed46d..739b29d 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -3653,6 +3653,7 @@ static inline unsigned long rlimit_max(unsigned int limit)
> #define SCHED_CPUFREQ_RT (1U << 0)
> #define SCHED_CPUFREQ_DL (1U << 1)
> #define SCHED_CPUFREQ_IOWAIT (1U << 2)
> +#define SCHED_CPUFREQ_IDLE (1U << 3)
>
> #define SCHED_CPUFREQ_RT_DL (SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL)
>
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index fd46593..084a98b 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -281,6 +281,12 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
>
> raw_spin_lock(&sg_policy->update_lock);
>
> + /* CPU is entering IDLE, reset flags without triggering an update */
> + if (flags & SCHED_CPUFREQ_IDLE) {

Will "flags == SCHED_CPUFREQ_IDLE" generate better assembly ?

> + sg_cpu->flags = 0;
> + goto done;
> + }
> +
> sg_cpu->util = util;
> sg_cpu->max = max;
> sg_cpu->flags = flags;
> @@ -293,6 +299,7 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
> sugov_update_commit(sg_policy, time, next_f);
> }
>
> +done:
> raw_spin_unlock(&sg_policy->update_lock);
> }
>
> diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
> index 0c00172..a844c91 100644
> --- a/kernel/sched/idle_task.c
> +++ b/kernel/sched/idle_task.c
> @@ -29,6 +29,10 @@ pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf
> put_prev_task(rq, prev);
> update_idle_core(rq);
> schedstat_inc(rq->sched_goidle);
> +
> + /* kick cpufreq (see the comment in kernel/sched/sched.h). */
> + cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IDLE);
> +
> return rq->idle;
> }
>
> --
> 2.7.4

--
viresh