Re: [RFC PATCH 47/86] rcu: select PREEMPT_RCU if PREEMPT

[Paul E. McKenney]

On Tue, Dec 05, 2023 at 12:18:26PM -0800, Ankur Arora wrote:
> 
> Paul E. McKenney <paulmck@xxxxxxxxxx> writes:
> 
> > On Tue, Dec 05, 2023 at 10:01:14AM -0500, Steven Rostedt wrote:
> >> On Mon, 4 Dec 2023 17:01:21 -0800
> >> "Paul E. McKenney" <paulmck@xxxxxxxxxx> wrote:
> >>
> >> > On Tue, Nov 28, 2023 at 11:53:19AM +0100, Thomas Gleixner wrote:
> >> > > Paul!
> >> > >
> >> > > On Tue, Nov 21 2023 at 07:19, Paul E. McKenney wrote:
> >> > > > On Tue, Nov 21, 2023 at 10:00:59AM -0500, Steven Rostedt wrote:
> ...
> >> > >   3) Looking at the initial problem Ankur was trying to solve there is
> >> > >      absolutely no acceptable solution to solve that unless you think
> >> > >      that the semantically invers 'allow_preempt()/disallow_preempt()'
> >> > >      is anywhere near acceptable.
> >> >
> >> > I am not arguing for allow_preempt()/disallow_preempt(), so for that
> >> > argument, you need to find someone else to argue with.  ;-)
> >>
> >> Anyway, there's still a long path before cond_resched() can be removed. It
> >> was a mistake by Ankur to add those removals this early (and he has
> >> acknowledged that mistake).
> >
> > OK, that I can live with.  But that seems to be a bit different of a
> > take than that of some earlier emails in this thread.  ;-)
> 
> Heh I think it's just that this thread goes to (far) too many places :).
> 
> As Steven says, the initial series touching everything all together
> was a mistake. V1 adds the new preemption model alongside the existing
> ones locally defines cond_resched() as nop.
> 
> That'll allow us to experiment and figure out where there are latency
> gaps.

Sounds very good!

Again, I am very supportive of the overall direction.  Devils and details
and all that.  ;-)

							Thanx, Paul