Re: [QUESTION/REGRESSION] Unbound kthreads scheduled on nohz_full CPUs after commit 041ee6f3727a

[sheviks]

Waiman Long <longman@xxxxxxxxxx> 於 2026年3月23日 週一 05:18 寫道：
>
> The plan is to make nohz_full also dynamically changeable at run time in
> the future. We are not there yet. Now HK_TYPE_KTHREAD is equivalent to
> HK_TYPE_DOMAIN.
>
> A CPU cannot be considered fully isolated if it is in either
> HK_TYPE_DOMAIN or HK_TYPE_KERNEL_NOISE. Currently, the nohz_full kernel
> parameter can be used to put a set of partially isolated CPUs in the
> nohz_full reservoir. To fully isolate them, some or all of them will be
> need to be put in an isolated cpuset partition. BTW, HK_TYPE_MANAGED_IRQ
> will be made to be dynamic too.
>
> That is my current view.
>

That sounds like a great roadmap. I am very much looking forward to
seeing the final implementation, as making nohz_full and managed IRQs
dynamic would be a significant improvement for runtime isolation
flexibility.

However, regarding the current state in 7.0rc4, I observed that
HK_TYPE_KTHREAD still appears to be initialized as
HK_TYPE_KERNEL_NOISE rather than HK_TYPE_DOMAIN in the initialization
path.
Perhaps this part of the alignment hasn't been merged into the mainline yet?

Thanks for the clarification and for your work on this!
Best regards,
Sheviks