linux-kernel - Re: [RFC PATCH v15 1/7] sched: Add CONFIG_SCHED_PROXY

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Message-ID: <CANDhNCrCmNVQjAy2pHY_K3VYR=f_44fqPRnAP-mr16yUhk8rPw@mail.gmail.com>
Date: Mon, 17 Mar 2025 15:44:11 +0100
From: John Stultz <jstultz@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: LKML <linux-kernel@...r.kernel.org>, Joel Fernandes <joelagnelf@...dia.com>, 
	Qais Yousef <qyousef@...alina.io>, Ingo Molnar <mingo@...hat.com>, 
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
	Dietmar Eggemann <dietmar.eggemann@....com>, Valentin Schneider <vschneid@...hat.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, 
	Zimuzo Ezeozue <zezeozue@...gle.com>, Mel Gorman <mgorman@...e.de>, Will Deacon <will@...nel.org>, 
	Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Metin Kaya <Metin.Kaya@....com>, 
	Xuewen Yan <xuewen.yan94@...il.com>, K Prateek Nayak <kprateek.nayak@....com>, 
	Thomas Gleixner <tglx@...utronix.de>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	Suleiman Souhlal <suleiman@...gle.com>, kernel-team@...roid.com
Subject: Re: [RFC PATCH v15 1/7] sched: Add CONFIG_SCHED_PROXY_EXEC & boot
 argument to enable/disable

On Mon, Mar 17, 2025 at 3:33 PM Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, Mar 12, 2025 at 03:11:31PM -0700, John Stultz wrote:
>
> > diff --git a/init/Kconfig b/init/Kconfig
> > index d0d021b3fa3b3..b989ddc27444e 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -875,6 +875,16 @@ config UCLAMP_BUCKETS_COUNT
> >
> >         If in doubt, use the default value.
> >
> > +config SCHED_PROXY_EXEC
> > +     bool "Proxy Execution"
> > +     default n
> > +     # Avoid some build failures w/ PREEMPT_RT until it can be fixed
> > +     depends on !PREEMPT_RT
>         depends on !SPM && !SCHED_CLASS_EXT
>
> for now, right?

Did you mean SMP there?  SMP is supported. Even with same rq proxying,
it just blocks the task and lets it sleep if the owner is on another
rq.

!SCHED_CLASS_EXT might be something to add, but mostly because the
SCHED_CLASS_EXT code probably doesn't have a way to understand the
split contexts yet.

I'll dig a bit more there.

Thanks so much for the feedback! Really appreciate it!
-john