linux-kernel - Re: [PATCH v2 6/6] sched: Default enable HRTICK

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Message-ID: <20260122114054.GA3372621@noisy.programming.kicks-ass.net>
Date: Thu, 22 Jan 2026 12:40:54 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Phil Auld <pauld@...hat.com>
Cc: tglx@...utronix.de, arnd@...db.de, anna-maria@...utronix.de,
	frederic@...nel.org, luto@...nel.org, mingo@...hat.com,
	juri.lelli@...hat.com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
	mgorman@...e.de, vschneid@...hat.com, linux-kernel@...r.kernel.org,
	oliver.sang@...el.com
Subject: Re: [PATCH v2 6/6] sched: Default enable HRTICK

On Wed, Jan 21, 2026 at 05:24:44PM -0500, Phil Auld wrote:
> Hi Peter,
> 
> On Wed, Jan 21, 2026 at 05:20:16PM +0100 Peter Zijlstra wrote:
> > ... for generic entry architectures. This decouples preemption from
> > CONFIG_HZ, leaving only the periodic load-balancer and various
> > accounting things relying on the tick.
> > 
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > ---
> >  kernel/sched/features.h |    5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > --- a/kernel/sched/features.h
> > +++ b/kernel/sched/features.h
> > @@ -63,8 +63,13 @@ SCHED_FEAT(DELAY_ZERO, true)
> >   */
> >  SCHED_FEAT(WAKEUP_PREEMPTION, true)
> >  
> > +#ifdef TIF_HRTIMER_REARM

Arguably this should be CONFIG_GENERIC_ENTRY I suppose

> > +SCHED_FEAT(HRTICK, true)
> > +SCHED_FEAT(HRTICK_DL, true)
> > +#else
> >  SCHED_FEAT(HRTICK, false)
> >  SCHED_FEAT(HRTICK_DL, false)
> > +#endif
> 
> I maybe be missing something. But the title of this patch
> and the above code do not seem to match.

You mean it only default enables it for a subset of architectures?