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From: Ankur Arora <ankur.a.arora@oracle.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ankur Arora <ankur.a.arora@oracle.com>, paulmck@kernel.org,
        Joel
 Fernandes <joel@joelfernandes.org>, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH 26/30] sched: handle preempt=voluntary under PREEMPT_AUTO
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Date: Mon, 11 Mar 2024 14:03:56 -0700
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Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Mon, 11 Mar 2024 at 13:10, Ankur Arora <ankur.a.arora@oracle.com> wrote:
>>
>> Ah, I see your point. Basically, keep the lazy semantics but -- in
>> addition -- also provide the ability to dynamically toggle
>> cond_resched(), might_reshed() as a feature to help move this along
>> further.
>
> Please, let's not make up any random hypotheticals.
>
> Honestly, if we ever hit the hypothetical scenario that Paul outlined, let's
>
>  (a) deal with it THEN, when we actually know what the situation is
>
>  (b) learn and document what it is that actually causes the odd behavior
>
> IOW, instead of assuming that some "cond_resched()" case would even be
> the right thing to do, maybe there are other issues going on?  Let's
> not paper over them by keeping some hack around - and *if* some
> cond_resched() model is actually the right model in some individual
> place, let's make it the rule that *when* we hit that case, we
> document it.
>
> And we should absolutely not have some hypothetical case keep us from
> just doing the right thing and getting rid of the existing
> cond_resched().
>
> Because any potential future case is *not* going to be the same
> cond_resched() that the current case is anyway. It is going to have
> some very different cause.

Ack that. And, thanks that makes sense to me.

--
ankur