Re: [PATCH tip/core/rcu 02/26] mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls

Joel Fernandes
2020-06-23T21:01:22Z

On Tue, Jun 23, 2020 at 01:55:08PM -0700, Paul E. McKenney wrote:
[..]
> > Just for my understanding, cond_resched_tasks_rcu_qs() may not help here
> > because preemption is not disabled right? Still I see no harm in using it
> > here either as it may give a slight speed up for tasks-RCU.
>
> The RCU-tasks stall-warning interval is ten minutes, and I have not yet
> seen evidence that we are getting close to that. If we do, then yes,
> a cond_resched_tasks_rcu_qs() might be in this code's future. But it
> does add overhead, so we need to see the evidence first.

Yes, true about that overhead. Ok, this is fine with me too, thanks :)

- Joel