linux-kernel - Re: [PATCH 1/5] sched: Add TIF_NEED_RESCHED

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Message-ID: <20241009121859.C2-B8P4L@linutronix.de>
Date: Wed, 9 Oct 2024 14:18:59 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: tglx@...utronix.de, mingo@...nel.org, linux-kernel@...r.kernel.org,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, ankur.a.arora@...cle.com,
	efault@....de
Subject: Re: [PATCH 1/5] sched: Add TIF_NEED_RESCHED_LAZY infrastructure

On 2024-10-07 09:46:10 [+0200], Peter Zijlstra wrote:
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -964,9 +963,9 @@ static bool set_nr_if_polling(struct tas
>  }
>  
>  #else
> -static inline bool set_nr_and_not_polling(struct task_struct *p)
> +static inline bool set_nr_and_not_polling(struct thread_info *ti, int tif)
>  {
> -	set_tsk_need_resched(p);
> +	atomic_long_or(1 << tif, (atomic_long_t *)&ti->flags);

	set_ti_thread_flag(ti, tif);
?
Not sure if there is a benefit over atomic_long_or() but you could avoid
the left shift. I know. Performance critical.

>  	return true;
>  }
>  

Sebastian