* rcu: make RCU_BOOST default on RT
@ 2018-11-01 23:25 Paul E. McKenney
2018-11-08 16:05 ` Sebastian Andrzej Siewior
0 siblings, 1 reply; 2+ messages in thread
From: Paul E. McKenney @ 2018-11-01 23:25 UTC (permalink / raw)
To: bigeasy; +Cc: linux-rt-users, linux-kernel
> Since it is no longer invoked from the softirq people run into OOM more
> often if the priority of the RCU thread is too low. Making boosting
> default on RT should help in those case and it can be switched off if
> someone knows better.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
> index 644264be90f0..0be2c96fb640 100644
> --- a/kernel/rcu/Kconfig
> +++ b/kernel/rcu/Kconfig
> @@ -36,7 +36,7 @@ config TINY_RCU
>
> config RCU_EXPERT
> bool "Make expert-level adjustments to RCU configuration"
> - default n
> + default y if PREEMPT_RT_FULL
Would it work to leave this as is, and ...
> help
> This option needs to be enabled if you wish to make
> expert-level adjustments to RCU configuration. By default,
> @@ -191,7 +191,7 @@ config RCU_FAST_NO_HZ
> config RCU_BOOST
> bool "Enable RCU priority boosting"
> depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
... make the above line instead be:
depends on (RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT) || PREEMPT_RT_FULL
Or am I missing something?
I agree that the risk might currently seem small, but if Linus ever
starts building PREEMPT_RT_FULL kernels, I really really do not want
RCU_EXPERT to be set. ;-)
Thanx, Paul
> - default n
> + default y if PREEMPT_RT_FULL
> help
> This option boosts the priority of preempted RCU readers that
> block the current preemptible RCU grace period for too long.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: rcu: make RCU_BOOST default on RT
2018-11-01 23:25 rcu: make RCU_BOOST default on RT Paul E. McKenney
@ 2018-11-08 16:05 ` Sebastian Andrzej Siewior
0 siblings, 0 replies; 2+ messages in thread
From: Sebastian Andrzej Siewior @ 2018-11-08 16:05 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: linux-rt-users, linux-kernel
On 2018-11-01 16:25:18 [-0700], Paul E. McKenney wrote:
> > --- a/kernel/rcu/Kconfig
> > +++ b/kernel/rcu/Kconfig
> > @@ -36,7 +36,7 @@ config TINY_RCU
> >
> > config RCU_EXPERT
> > bool "Make expert-level adjustments to RCU configuration"
> > - default n
> > + default y if PREEMPT_RT_FULL
>
> Would it work to leave this as is, and ...
>
> > help
> > This option needs to be enabled if you wish to make
> > expert-level adjustments to RCU configuration. By default,
> > @@ -191,7 +191,7 @@ config RCU_FAST_NO_HZ
> > config RCU_BOOST
> > bool "Enable RCU priority boosting"
> > depends on RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT
>
> ... make the above line instead be:
>
> depends on (RT_MUTEXES && PREEMPT_RCU && RCU_EXPERT) || PREEMPT_RT_FULL
>
> Or am I missing something?
>
> I agree that the risk might currently seem small, but if Linus ever
> starts building PREEMPT_RT_FULL kernels, I really really do not want
> RCU_EXPERT to be set. ;-)
okay, this would work. Let me teak this in my current tree.
> Thanx, Paul
Sebastian
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2018-11-08 16:05 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-01 23:25 rcu: make RCU_BOOST default on RT Paul E. McKenney
2018-11-08 16:05 ` Sebastian Andrzej Siewior
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).