Re: [PATCH] support "THPeligible" semantics for mTHP with anonymous shmem

[David Hildenbrand]

On 01.07.24 08:47, Baolin Wang wrote:
> CC Barry.
>
> On 2024/6/28 18:49, Bang Li wrote:
> > After the commit 7fb1b252afb5 ("mm: shmem: add mTHP support for
> > anonymous shmem"), we can configure different policies through
> > the multi-size THP sysfs interface for anonymous shmem. But
> > currently "THPeligible" indicates only whether the mapping is
> > eligible for allocating THP-pages as well as the THP is PMD
> > mappable or not for anonymous shmem, we need to support semantics
> > for mTHP with anonymous shmem similar to those for mTHP with
> > anonymous memory.
>
> I did not see a consensus that "THP*" related statistics should contain
> mTHP in previous discussion [1].
>
> In addition, if we all agree that "THPeligible" should include mTHP
> statistics, you should update the corresponding documentation to keep
> consistency.
>
> [1]
> https://lore.kernel.org/linux-mm/202406262300.iAURISyJ-lkp@xxxxxxxxx/T/#md7a77056110cebcc2a9b3cd7e4a8d682667f6ba5

Fortunately, documentation (Documentation/filesystems/proc.rst) says:

"THPeligible" indicates whether the mapping is eligible for allocating 
naturally aligned THP pages of any currently enabled size. 1 if true, 0 
otherwise."

So that documentation is already pretty clear (we just have to make sure 
the other ones are properly documented, for example as raised in reply 
to [1]).

--
Cheers,

David / dhildenb