linux-kernel - Re: [PATCH v8 04/16] sched/core: uclamp: Add system default clamps

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Date:   Thu, 9 May 2019 09:45:34 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-api@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Paul Turner <pjt@...gle.com>,
        Quentin Perret <quentin.perret@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Steve Muckle <smuckle@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH v8 04/16] sched/core: uclamp: Add system default clamps

On 08-May 21:00, Peter Zijlstra wrote:
> 
> There was a bunch of repetition that seemed fragile; does something like
> the below make sense?

Absolutely yes... will add to v9, thanks.
 
> Index: linux-2.6/kernel/sched/core.c
> ===================================================================
> --- linux-2.6.orig/kernel/sched/core.c
> +++ linux-2.6/kernel/sched/core.c
> @@ -770,6 +770,9 @@ unsigned int sysctl_sched_uclamp_util_ma
>  /* All clamps are required to be less or equal than these values */
>  static struct uclamp_se uclamp_default[UCLAMP_CNT];
>  
> +#define for_each_clamp_id(clamp_id)	\
> +	for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
> +
>  /* Integer rounded range for each bucket */
>  #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
>  
> @@ -790,6 +793,12 @@ static inline unsigned int uclamp_none(i
>  	return SCHED_CAPACITY_SCALE;
>  }
>  
> +static inline void uclamp_se_set(struct uclamp_se *uc_se, unsigned int value)
> +{
> +	uc_se->value = value;
> +	uc_se->bucket_id = uclamp_bucket_id(value);
> +}
> +
>  static inline unsigned int
>  uclamp_idle_value(struct rq *rq, unsigned int clamp_id, unsigned int clamp_value)
>  {
> @@ -977,7 +986,7 @@ static inline void uclamp_rq_inc(struct
>  	if (unlikely(!p->sched_class->uclamp_enabled))
>  		return;
>  
> -	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id)
> +	for_each_clamp_id(clamp_id)
>  		uclamp_rq_inc_id(p, rq, clamp_id);
>  
>  	/* Reset clamp idle holding when there is one RUNNABLE task */
> @@ -992,7 +1001,7 @@ static inline void uclamp_rq_dec(struct
>  	if (unlikely(!p->sched_class->uclamp_enabled))
>  		return;
>  
> -	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id)
> +	for_each_clamp_id(clamp_id)
>  		uclamp_rq_dec_id(p, rq, clamp_id);
>  }
>  
> @@ -1021,16 +1030,13 @@ int sysctl_sched_uclamp_handler(struct c
>  	}
>  
>  	if (old_min != sysctl_sched_uclamp_util_min) {
> -		uclamp_default[UCLAMP_MIN].value =
> -			sysctl_sched_uclamp_util_min;
> -		uclamp_default[UCLAMP_MIN].bucket_id =
> -			uclamp_bucket_id(sysctl_sched_uclamp_util_min);
> +		uclamp_se_set(&uclamp_default[UCLAMP_MIN],
> +			      sysctl_sched_uclamp_util_min);
>  	}
> +
>  	if (old_max != sysctl_sched_uclamp_util_max) {
> -		uclamp_default[UCLAMP_MAX].value =
> -			sysctl_sched_uclamp_util_max;
> -		uclamp_default[UCLAMP_MAX].bucket_id =
> -			uclamp_bucket_id(sysctl_sched_uclamp_util_max);
> +		uclamp_se_set(&uclamp_default[UCLAMP_MAX],
> +			      sysctl_sched_uclamp_util_max);
>  	}
>  
>  	/*
> @@ -1052,7 +1058,7 @@ static void uclamp_fork(struct task_stru
>  {
>  	unsigned int clamp_id;
>  
> -	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id)
> +	for_each_clamp_id(clamp_id)
>  		p->uclamp[clamp_id].active = false;
>  }
>  
> @@ -1067,17 +1073,12 @@ static void __init init_uclamp(void)
>  		cpu_rq(cpu)->uclamp_flags = 0;
>  	}
>  
> -	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
> -		struct uclamp_se *uc_se = &init_task.uclamp_req[clamp_id];
> -
> -		uc_se->value = uclamp_none(clamp_id);
> -		uc_se->bucket_id = uclamp_bucket_id(uc_se->value);
> -	}
> +	for_each_clamp_id(clamp_id)
> +		uclamp_se_set(&init_task.uclamp_req[clamp_id], uclamp_none(clamp_id));
>  
>  	/* System defaults allow max clamp values for both indexes */
> -	uc_max.value = uclamp_none(UCLAMP_MAX);
> -	uc_max.bucket_id = uclamp_bucket_id(uc_max.value);
> -	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id)
> +	uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX));
> +	for_each_clamp_id(clamp_id)
>  		uclamp_default[clamp_id] = uc_max;
>  }
>  
> 

-- 
#include <best/regards.h>

Patrick Bellasi