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

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Message-ID: <3de6a9db-a122-420d-a845-2087136a0d6c@linux.ibm.com>
Date: Sun, 13 Jul 2025 10:20:25 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: Mark Rutland <mark.rutland@....com>, catalin.marinas@....com,
        will@...nel.org, maddy@...ux.ibm.com
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, tglx@...utronix.de, bigeasy@...utronix.de,
        vschneid@...hat.com, dietmar.eggemann@....com, rostedt@...dmis.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/1] sched: preempt: Move dynamic keys into kernel/sched


> On Tue, Jun 10, 2025 at 01:23:44PM +0530, 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 spread currently across entry/common.c, arm64 and latest being
>> powerpc. There is little arch specific to it. For example, arm64,
>> powerpc does the same thing. 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.
>>
>> This is more of code movement. No functional change.
>>
>> Suggested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
>> Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
> 
> I've tested this on arm64 atop v6.16-rc2, building and booting defconfig
> and defconfig + PREEMPT_DYNAMIC=y.
> 

Hi Mark. Thanks for testing it. Sorry for delayed response.

> It builds cleanly, boots fine, and I think this is obviously correct
> given it's just moving things around, so FWIW:
> 
> Acked-by: Mark Rutland <mark.rutland@....com>
> 
> Catalin, Will, are you happy with this?
>

Thank you will for the tags.


> I assume this would go via the tip tree?
> 

Maddy, are you okay with this?

I would request it to go via tip tree.