Re: [PATCH] rcu/nocb: Add an option to ON/OFF an offloading from RT context

From: Paul E. McKenney
Date: Tue May 10 2022 - 13:15:02 EST


On Tue, May 10, 2022 at 04:07:23PM +0200, Sebastian Andrzej Siewior wrote:
> On 2022-05-05 12:09:15 [-0700], Paul E. McKenney wrote:
> > All good points!
> >
> > Some questions and comments below.
> >
> > Adding Sebastian on CC for his perspective.
>
> Thank you.
> I may missing things, I tried to digest the thread…
>
> In my understanding: The boosting option is used to allow a SCHED_OTHER
> task within a RCU section to allow to leave the RCU section while tasks
> with higher priority occupy the CPU.
> As far as the RCU callbacks are concerned, I'm not aware that it would
> be beneficial to run them with an elevated priority. On SMP systems,
> there is the suggestion to have a housekeeping CPU and to offload the
> RCU callbacks to this CPU and no to bother the CPU with the RT workload.

Agreed, even within RT, there are multiple ways to get this job done.

Thanx, Paul