linux-kernel - Re: [PATCH v4 2/4] sched/core: Propagate parent task's latency requirements to the child task

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Date:   Tue, 25 Feb 2020 12:02:26 +0530
From:   Pavan Kondeti <pkondeti@...eaurora.org>
To:     Parth Shah <parth@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, qais.yousef@....com,
        chris.hyser@...cle.com, patrick.bellasi@...bug.net,
        valentin.schneider@....com, David.Laight@...LAB.COM,
        pjt@...gle.com, pavel@....cz, tj@...nel.org,
        dhaval.giani@...cle.com, qperret@...gle.com,
        tim.c.chen@...ux.intel.com
Subject: Re: [PATCH v4 2/4] sched/core: Propagate parent task's latency
 requirements to the child task

On Mon, Feb 24, 2020 at 02:29:16PM +0530, Parth Shah wrote:
> Clone parent task's latency_nice attribute to the forked child task.
> 
> Reset the latency_nice value to default value when the child task is
> set to sched_reset_on_fork.
> 
> Signed-off-by: Parth Shah <parth@...ux.ibm.com>
> Reviewed-by: Qais Yousef <qais.yousef@....com>
> ---
>  kernel/sched/core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 377ec26e9159..65b6c00d6dac 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2860,6 +2860,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
>  	 */
>  	p->prio = current->normal_prio;
>  
> +	/* Propagate the parent's latency requirements to the child as well */
> +	p->latency_nice = current->latency_nice;
> +
>  	uclamp_fork(p);
>  
>  	/*
> @@ -2876,6 +2879,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
>  		p->prio = p->normal_prio = __normal_prio(p);
>  		set_load_weight(p, false);
>  
> +		p->latency_nice = DEFAULT_LATENCY_NICE;
>  		/*
>  		 * We don't need the reset flag anymore after the fork. It has
>  		 * fulfilled its duty:
> -- 
> 2.17.2
> 

LGTM.

latency_nice value initialization is missing for the init_task.

Thanks,
Pavan

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