Re: [PATCH v3 13/13] mm: introduce arch_wants_lazy_mmu_mode()

David Hildenbrand
2025-10-23T20:10:46Z

On 15.10.25 10:27, Kevin Brodsky wrote:
> powerpc decides at runtime whether the lazy MMU mode should be used.
>
> To avoid the overhead associated with managing
> task_struct::lazy_mmu_state if the mode isn't used, introduce
> arch_wants_lazy_mmu_mode() and bail out of lazy_mmu_mode_* if it
> returns false. Add a default definition returning true, and an
> appropriate implementation for powerpc.
>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
> ---
> This patch seemed like a good idea to start with, but now I'm not so
> sure that the churn added to the generic layer is worth it.

Exactly my thoughts :)

I think we need evidence that this is really worth it for optimizing out
basically a counter update on powerpc.

--
Cheers

David / dhildenb