linux-kernel - Re: [PATCH 1/2] sched/uclamp: Alaways using uclamp_is

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d7713049-5b44-4e86-8c0d-ca2c365c925f@arm.com>
Date: Thu, 13 Feb 2025 18:15:37 +0000
From: Christian Loehle <christian.loehle@....com>
To: Xuewen Yan <xuewen.yan@...soc.com>, mingo@...hat.com,
 peterz@...radead.org, juri.lelli@...hat.com, vincent.guittot@...aro.org
Cc: dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
 mgorman@...e.de, vschneid@...hat.com, qyousef@...alina.io,
 ke.wang@...soc.com, di.shen@...soc.com, xuewen.yan94@...il.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] sched/uclamp: Alaways using uclamp_is_used()

On 2/13/25 09:15, Xuewen Yan wrote:
> Now, we have the uclamp_is_used() func to judge the uclamp enabled,
> so replace the static_branch_unlikely(&sched_uclamp_used) with it.
> 
> Signed-off-by: Xuewen Yan <xuewen.yan@...soc.com>
> ---
>  kernel/sched/core.c  |  4 ++--
>  kernel/sched/sched.h | 28 ++++++++++++++--------------
>  2 files changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 165c90ba64ea..841147759ec7 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1756,7 +1756,7 @@ static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
>  	 * The condition is constructed such that a NOP is generated when
>  	 * sched_uclamp_used is disabled.
>  	 */
> -	if (!static_branch_unlikely(&sched_uclamp_used))
> +	if (!uclamp_is_used())
>  		return;
>  
>  	if (unlikely(!p->sched_class->uclamp_enabled))
> @@ -1783,7 +1783,7 @@ static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
>  	 * The condition is constructed such that a NOP is generated when
>  	 * sched_uclamp_used is disabled.
>  	 */
> -	if (!static_branch_unlikely(&sched_uclamp_used))
> +	if (!uclamp_is_used())
>  		return;
>  
>  	if (unlikely(!p->sched_class->uclamp_enabled))
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 38e0e323dda2..f5de05354d80 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -3394,6 +3394,19 @@ static inline bool update_other_load_avgs(struct rq *rq) { return false; }
>  
>  unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id);
>  
> +/*
> + * When uclamp is compiled in, the aggregation at rq level is 'turned off'
> + * by default in the fast path and only gets turned on once userspace performs
> + * an operation that requires it.
> + *
> + * Returns true if userspace opted-in to use uclamp and aggregation at rq level
> + * hence is active.
> + */
> +static inline bool uclamp_is_used(void)
> +{
> +	return static_branch_likely(&sched_uclamp_used);
> +}
> +
>  static inline unsigned long uclamp_rq_get(struct rq *rq,
>  					  enum uclamp_id clamp_id)
>  {
> @@ -3417,7 +3430,7 @@ static inline bool uclamp_rq_is_capped(struct rq *rq)
>  	unsigned long rq_util;
>  	unsigned long max_util;
>  
> -	if (!static_branch_likely(&sched_uclamp_used))
> +	if (!uclamp_is_used())
>  		return false;
>  
>  	rq_util = cpu_util_cfs(cpu_of(rq)) + cpu_util_rt(rq);
> @@ -3426,19 +3439,6 @@ static inline bool uclamp_rq_is_capped(struct rq *rq)
>  	return max_util != SCHED_CAPACITY_SCALE && rq_util >= max_util;
>  }
>  
> -/*
> - * When uclamp is compiled in, the aggregation at rq level is 'turned off'
> - * by default in the fast path and only gets turned on once userspace performs
> - * an operation that requires it.
> - *
> - * Returns true if userspace opted-in to use uclamp and aggregation at rq level
> - * hence is active.
> - */
> -static inline bool uclamp_is_used(void)
> -{
> -	return static_branch_likely(&sched_uclamp_used);
> -}
> -
>  #define for_each_clamp_id(clamp_id) \
>  	for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
>  

Reviewed-by: Christian Loehle <christian.loehle@....com>