linux-kernel - Re: [PATCH v2 1/1] sched: preempt: Move dynamic keys into kernel/sched

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Message-ID: <7c70fac4-3cc7-4bf1-a3f1-aa1c61f67425@linux.ibm.com>
Date: Tue, 12 Aug 2025 23:51:10 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mingo@...hat.com, peterz@...radead.org
Cc: mark.rutland@....com, bigeasy@...utronix.de, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, venkat88@...ux.ibm.com,
        tglx@...utronix.de, maddy@...ux.ibm.com, will@...nel.org
Subject: Re: [PATCH v2 1/1] sched: preempt: Move dynamic keys into
 kernel/sched



On 7/16/25 15:17, Shrikanth Hegde wrote:
> Dynamic preemption can be static key or static call based.
> Static key is used to check kernel preemption depending on
> the current preemption model. i.e enable for lazy, full.
> 
> Code is currently spread across entry/common.c, arm64 and latest being
> powerpc. There is little arch specific to it. arm64, powerpc have the
> same code. It is better to move it into kernel/sched since preemption
> is more closely associated with scheduler.
> 
> Plus, Any new arch that wants dynamic preemption enabled need to have
> only HAVE_PREEMPT_DYNAMIC_KEY.
> 
> Suggested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
> Acked-by: Mark Rutland <mark.rutland@....com>
> Acked-by: Will Deacon <will@...nel.org>
> Acked-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
> ---
>   arch/arm64/include/asm/preempt.h   |  1 -
>   arch/arm64/kernel/entry-common.c   |  8 --------
>   arch/powerpc/include/asm/preempt.h | 16 ----------------
>   arch/powerpc/kernel/interrupt.c    |  4 ----
>   include/linux/irq-entry-common.h   |  1 -
>   include/linux/sched.h              |  8 ++++++++
>   kernel/entry/common.c              |  1 -
>   kernel/sched/core.c                |  4 ++++
>   8 files changed, 12 insertions(+), 31 deletions(-)
>   delete mode 100644 arch/powerpc/include/asm/preempt.h
> 

Hi Ingo, Peter.

Does this change makes sense? Are there any further concerns that you see?
Also can it go via tip tree?

Patch applies on 6.17-rc1 (at commit ca76508b9352e8c770b58213cc6c4700e459b7c2)