linux-kernel - Re: [RFC PATCH 31/86] x86/thread_info: add TIF_NEED_RESCHED

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Message-ID: <20231107182637.20f71eba@gandalf.local.home>
Date:   Tue, 7 Nov 2023 18:26:37 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Ankur Arora <ankur.a.arora@...cle.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        peterz@...radead.org, 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,
        geert@...ux-m68k.org, glaubitz@...sik.fu-berlin.de,
        anton.ivanov@...bridgegreys.com, mattst88@...il.com,
        krypton@...ich-teichert.org, David.Laight@...LAB.COM,
        richard@....at, mjguzik@...il.com
Subject: Re: [RFC PATCH 31/86] x86/thread_info: add TIF_NEED_RESCHED_LAZY

On Tue,  7 Nov 2023 13:57:17 -0800
Ankur Arora <ankur.a.arora@...cle.com> wrote:

> Add a new flag, TIF_NEED_RESCHED_LAZY which with TIF_NEED_RESCHED
> gives the scheduler two levels of rescheduling priority:
> TIF_NEED_RESCHED means that rescheduling happens at the next
> opportunity; TIF_NEED_RESCHED_LAZY is used to note that a
> reschedule is needed but does not impose any other constraints
> on the scheduler.

Please add:

Link: https://lore.kernel.org/lkml/87cyyfxd4k.ffs@tglx/
Link: https://lore.kernel.org/lkml/87jzshhexi.ffs@tglx/

For each of the patches that were based off of Thomas's patch.

Thanks!

-- Steve



> 
> Originally-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
> ---
>  arch/x86/include/asm/thread_info.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> index d63b02940747..114d12120051 100644
> --- a/arch/x86/include/asm/thread_info.h
> +++ b/arch/x86/include/asm/thread_info.h
> @@ -81,8 +81,9 @@ struct thread_info {
>  #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
>  #define TIF_SIGPENDING		2	/* signal pending */
>  #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
> -#define TIF_SINGLESTEP		4	/* reenable singlestep on user return*/
> -#define TIF_SSBD		5	/* Speculative store bypass disable */
> +#define TIF_NEED_RESCHED_LAZY	4	/* Lazy rescheduling */
> +#define TIF_SINGLESTEP		5	/* reenable singlestep on user return*/
> +#define TIF_SSBD		6	/* Speculative store bypass disable */
>  #define TIF_SPEC_IB		9	/* Indirect branch speculation mitigation */
>  #define TIF_SPEC_L1D_FLUSH	10	/* Flush L1D on mm switches (processes) */
>  #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
> @@ -104,6 +105,7 @@ struct thread_info {
>  #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
>  #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
>  #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
> +#define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
>  #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
>  #define _TIF_SSBD		(1 << TIF_SSBD)
>  #define _TIF_SPEC_IB		(1 << TIF_SPEC_IB)