Re: [PATCH rcu 06/11] osnoise: provide quiescent states

[Boqun Feng]

On Tue, Mar 04, 2025 at 02:21:27PM -0500, Steven Rostedt wrote:
> On Mon, 24 Feb 2025 19:55:11 -0800
> Boqun Feng <boqun.feng@xxxxxxxxx> wrote:
> 
> > From: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
> > 
> > To reduce RCU noise for nohz_full configurations, osnoise depends
> > on cond_resched() providing quiescent states for PREEMPT_RCU=n
> > configurations. For PREEMPT_RCU=y configurations -- where
> > cond_resched() is a stub -- we do this by directly calling
> > rcu_momentary_eqs().
> > 
> > With (PREEMPT_LAZY=y, PREEMPT_DYNAMIC=n), however, we have a
> > configuration with (PREEMPTION=y, PREEMPT_RCU=n) where neither
> > of the above can help.
> > 
> > Handle that by providing an explicit quiescent state here for all
> > configurations.
> > 
> > As mentioned above this is not needed for non-stubbed cond_resched(),
> > but, providing a quiescent state here just pulls in one that a future
> > cond_resched() would provide, so doesn't cause any extra work for
> > this configuration.
> > 
> > Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> 
> Acked-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> 

Applied, thanks!

Regards,
Boqun

> -- Steve
> 
> > Suggested-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Acked-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> > Signed-off-by: Ankur Arora <ankur.a.arora@xxxxxxxxxx>
> > Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> > Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
> > ---