linux-kernel - Re: [PATCH v3 1/3] sched: Don't account execution time for task group

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Message-ID: <20231106124912.GM8262@noisy.programming.kicks-ass.net>
Date:   Mon, 6 Nov 2023 13:49:12 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] sched: Don't account execution time for task group

On Tue, Oct 31, 2023 at 08:59:26PM +0800, Yajun Deng wrote:
> The rt entity can be a task group. We will account execution time for
> each task. For consistency, we don't need to account execution time for
> task group.
> 
> Pass a parameter to update_current_exec_runtime, let the caller decide
> whether account execution time.
> 

> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 6aaf0a3d6081..79cf80d73822 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1018,7 +1018,8 @@ static void update_curr_rt(struct rq *rq)
>  
>  	trace_sched_stat_runtime(curr, delta_exec, 0);
>  
> -	update_current_exec_runtime(curr, now, delta_exec);
> +	update_current_exec_runtime(curr, now, delta_exec,
> +				    rt_entity_is_task(rt_se));
>  
>  	if (!rt_bandwidth_enabled())
>  		return;

ok, I think I've managed to confuse myself again.

But at this point rt_se := &rq->curr->rt, which is *always* a task, no?