Re: [PATCH 1/5] s390/tick: Remove CIF_NOHZ_DELAY flag

[Heiko Carstens <hca@linux.ibm.com>]

On Tue, Jun 09, 2026 at 12:04:08PM +0200, Mete Durlu wrote:
> On 6/9/26 11:52, Christian Loehle wrote:
> > > > > Remove obsolete tick delay heuristic [1]. The upcoming cpuidle driver
> > > > > handles frequent sleep/wakeup cycles more effectively.
> > > > > 
> > > > > [1] https://lore.kernel.org/all/20090929122533.402715150@de.ibm.com/
> > > > > 
> > > > > Suggested-by: Heiko Carstens <hca@linux.ibm.com>
> > > > > Signed-off-by: Mete Durlu <meted@linux.ibm.com>
> > > > > ---
> > > > For bisectibility does it make sense to move this and 2/5 to the end?
> > > 
> > > I am unable to see how that would help. Could you elaborate?
> > 
> > CIF_NOHZ_DELAY is only obsolete because of the new s390 cpuidle driver
> > handles NOHZ better overall right?
> > So my suggestion was to only obsolete it once everything is in place?
> 
> CIF_NOHZ_DELAY could modify the idle driver's decisions when it comes to
> disabling the scheduling tick. It could be hard to bisect a problem with
> the driver if we move the removal of the flag after the drivers
> introduction. Because then the commit that enables the driver can have
> a significantly different behavior.
> 
> Plus,having the flag obsolete without any other mechanism doing a
> similar job would make the effect and related behavior more visible and
> easier to debug.

The flag is questionable since a long time. So I wouldn't focus on the
question if the removal comes at the beginning or end of this series.
I'm more than happy to see it go.