Re: [PATCH] mm/rmap: optimize folio_move_anon_rmap()

[David Hildenbrand <david@redhat.com>]

On 12.05.24 14:35, Chen Taotao wrote:
> When a folio belongs exclusively to one process after a COW event,
> folio_move_anon_rmap() always moves the folio into the anon_vma
> belongs only to this process.
> 
> However, if the folio already belongs to the anon_vma of the this
> process, we don't need to move it again. In this case, we first
> check if the folio already belongs to the anna_vma of the this
> process, and only move it if it does not.
> 
> The above changes may improve the performance of vm faults in some
> scenarios, because the performance loss caused by WRITE_ONCE() is
> much more than the performance loss caused by add a judgment.

Please proof that by real numbers. I don't think it will make a real 
difference, and we likely don't want that change.


-- 
Cheers,

David / dhildenb