On Fri, Apr 8, 2022 at 12:57 AM Kalesh Singh <kaleshsingh@xxxxxxxxxx> wrote: [..] > +config RCU_EXP_KTHREAD > + bool "Perform RCU expedited work in a real-time kthread" > + depends on RCU_BOOST && RCU_EXPERT Doesn't this disable the fix if a system is not RCU_EXPERT ? Please see the definition of RCU_EXPERT: "This option needs to be enabled if you wish to make expert-level adjustments to RCU configuration." I don't think a bug fix counts as an expert-level adjustment. > + default !PREEMPT_RT && NR_CPUS <= 32 What is the benefit of turning it off on PREEMPT_RT, even if PREEMPT_RT does not use expedited GPs much post-boot? I would think in the future if PREEMPT_RT ever uses expedited GPs, they would want this feature even more. I'd rather be future-proof now as I don't see any advantages of disabling it on !PREEMPT_RT (And a drawback that the fix won't apply to those systems). Also will keep the config simple. > + help > + Use this option to further reduce the latencies of expedited > + grace periods at the expense of being more disruptive. > + > + Accept the default if unsure. > + > config RCU_NOCB_CPU > bool "Offload RCU callback processing from boot-selected CPUs" > depends on TREE_RCU [...] Thanks, - Joel
