Re: Arches that don't support PREEMPT

Ingo Molnar
2023-09-20T07:32:45Z

* 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