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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date:   Wed, 20 Sep 2023 09:32:38 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: Arches that don't support PREEMPT
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* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Tue, 19 Sep 2023 20:31:50 +0200
> Thomas Gleixner <tglx@linutronix.de> wrote:
> 
> > The removal of cond_resched() might cause latencies, but then I doubt
> > that these museus pieces are used for real work :)
> 
> We could simply leave the cond_resched() around but defined as nops for
> everything but the "nostalgia club" to keep them from having any regressions.

That's not a good idea IMO, it's an invitation for accelerated rate bitrot 
turning cond_resched() meaningless very quickly.

We should remove cond_resched() - but probably not as the first step. They 
are conceptually independent of NEED_RESCHED_LAZY and we don't *have to* 
remove them straight away.

By removing cond_resched() separately there's an easily bisectable point to 
blame for any longer latencies on legacy platforms, should any of them 
still be used with recent kernels.

Thanks,

	Ingo