Re: [PATCH 11/20] sched: Handle CPU isolation on last resort fallback rq selection

[Will Deacon]

On Fri, Sep 27, 2024 at 12:48:59AM +0200, Frederic Weisbecker wrote:
> When a kthread or any other task has an affinity mask that is fully
> offline or unallowed, the scheduler reaffines the task to all possible
> CPUs as a last resort.
> 
> This default decision doesn't mix up very well with nohz_full CPUs that
> are part of the possible cpumask but don't want to be disturbed by
> unbound kthreads or even detached pinned user tasks.
> 
> Make the fallback affinity setting aware of nohz_full. This applies to
> all architectures supporting nohz_full except arm32. However this
> architecture that overrides the task possible mask is unlikely to be
> willing to integrate new development.

I'm not sure I understand this last sentence. The possible mask is
overridden for 32-bit tasks on an *arm64* kernel when running on an SoC
featuring some CPUs that can execute only 64-bit tasks. Who is unwilling
to integrate what?

Will