Re: [PATCH] sched: Remove CONFIG_RT_GROUP_SCHED

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2026-11-05 07:19:27 [-1000], Tejun Heo wrote:
> Hello, Sebastian.
Hi Tejun,

> 
> I'm not against it but wonder whether it'd be useful to do it more gradually
> so that people can pipe up if they depend on it. ie. Mark it deprecated and
> put it behind EXPORT for a bit and then BROKEN before actual removal.

I would be surprised if this is actually used especially since it is
cg-v1 and v2 is the default/ used by everyone (?). 

This depended on !PREEMPT_RT in the RT queue. People asked if this can
be enabled because it looked useful/ for their use case. I researched
why it was like this and dropped that restriction. People then asked if
it is broken on RT because it is now working properly. I have never been
told _what_ is broken or *why* because nobody came back.
Later I've been told (there was an attempt to explain it to me, it was
late in the morning) and if I piece it properly together then, it could
work in UP environment but on SMP the accounting is wrong and therefore
the runtime/ preemption is not working as it should.

I didn't add this to the commit description because I would classify
this as hearsay and we do facts here. PeterZ might know more.
From what I know, people who asked for it either have a different
solution or eyeball HCBS.

> Thanks.

Sebastian