linux-kernel - Re: [RFC PATCH 00/86] Make the kernel preemptible

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Message-ID: <20231108121641.GC4779@noisy.programming.kicks-ass.net>
Date:   Wed, 8 Nov 2023 13:16:41 +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,
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        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,
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        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
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        krypton@...ich-teichert.org, rostedt@...dmis.org,
        David.Laight@...lab.com, richard@....at, mjguzik@...il.com
Subject: Re: [RFC PATCH 00/86] Make the kernel preemptible

On Wed, Nov 08, 2023 at 12:14:15PM +0100, Peter Zijlstra wrote:

> I would really suggest you start with transforming VOLUNTARY into the
> LAZY thing, keep it as simple and narrow as possible.

Possibly make it worse first, add LAZY as a fourth option, then show it
makes VOLUNTARY redundant, kill that.

> Once you've got that done, then you can try and argue that NONE makes no
> sense and try and take it out.

This also pushes out having to deal with the !PREEMPT archs until the
very last moment.

And once you're here, cond_resched() should be an obvious no-op function
and you can go delete them.

Anyway, as said, smaller steps more better. Nobody likes 86 patches in
their inbox in the morning (or at any time really).