linux-kernel - Re: [RFC PATCH 35/86] thread_info: change to tif_need_resched(resched

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Date:   Wed, 8 Nov 2023 10:00:11 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ankur Arora <ankur.a.arora@...cle.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        torvalds@...ux-foundation.org, paulmck@...nel.org,
        linux-mm@...ck.org, x86@...nel.org, akpm@...ux-foundation.org,
        luto@...nel.org, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, willy@...radead.org, mgorman@...e.de,
        jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        jgross@...e.com, andrew.cooper3@...rix.com, mingo@...nel.org,
        bristot@...nel.org, mathieu.desnoyers@...icios.com,
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        anton.ivanov@...bridgegreys.com, mattst88@...il.com,
        krypton@...ich-teichert.org, rostedt@...dmis.org,
        David.Laight@...lab.com, richard@....at, mjguzik@...il.com
Subject: Re: [RFC PATCH 35/86] thread_info: change to
 tif_need_resched(resched_t)

On Tue, Nov 07, 2023 at 01:57:21PM -0800, Ankur Arora wrote:

> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 95d47783ff6e..5f0d7341cb88 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2172,9 +2172,11 @@ static inline int rwlock_needbreak(rwlock_t *lock)
>  
>  static __always_inline bool need_resched(void)
>  {
> -	return unlikely(tif_need_resched());
> +	return unlikely(tif_need_resched(RESCHED_eager) ||
> +			tif_need_resched(RESCHED_lazy));
>  }
>  
> +

We really needed this extra blank line, yes? :-)

>  /*
>   * Wrappers for p->thread_info->cpu access. No-op on UP.
>   */
> diff --git a/include/linux/sched/idle.h b/include/linux/sched/idle.h
> index 478084f9105e..719416fe8ddc 100644
> --- a/include/linux/sched/idle.h
> +++ b/include/linux/sched/idle.h
> @@ -63,7 +63,7 @@ static __always_inline bool __must_check current_set_polling_and_test(void)
>  	 */
>  	smp_mb__after_atomic();
>  
> -	return unlikely(tif_need_resched());
> +	return unlikely(need_resched());
>  }

You're stacking unlikely's, need_resched() already has unlikely.