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

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Date:   Wed, 08 Nov 2023 12:46:00 -0800
From:   Ankur Arora <ankur.a.arora@...cle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ankur Arora <ankur.a.arora@...cle.com>,
        linux-kernel@...r.kernel.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 00/86] Make the kernel preemptible


Peter Zijlstra <peterz@...radead.org> writes:

> On Wed, Nov 08, 2023 at 11:22:27AM -0500, Steven Rostedt wrote:
>
>> Peter, how can you say we can get rid of cond_resched() in NONE when you
>
> Because that would fix none to actually be none. Who cares.
>
>> > Look at my PoC: https://lore.kernel.org/lkml/87jzshhexi.ffs@tglx/
>>
>> And I've been saying that many times already ;-)
>
> Why should I look at random patches on the interweb to make sense of
> these patches here?
>
> That just underlines these here patches are not making sense.

Yeah, I'm changing too many things structural things all together.

Let me redo this. This time limiting the changes to the scheduler
adding a preemption model which adds the lazy-bit and which can
behave in ways that are similar to preempt=none/full differently
by toggling the treatment of lazy-bit.

This keeps the current models as it is.

And, once that makes sense to people, then we can decide how best to
remove cond_resched() etc.

--
ankur