Re: [RFC 1/3] mm: add large zero page for efficient zeroing of larger segments

[David Hildenbrand]

On 16.05.25 12:10, Pankaj Raghav wrote:
> Introduce LARGE_ZERO_PAGE of size 2M as an alternative to ZERO_PAGE of
> size PAGE_SIZE.
>
> There are many places in the kernel where we need to zeroout larger
> chunks but the maximum segment we can zeroout at a time is limited by
> PAGE_SIZE.
>
> This is especially annoying in block devices and filesystems where we
> attach multiple ZERO_PAGEs to the bio in different bvecs. With multipage
> bvec support in block layer, it is much more efficient to send out
> larger zero pages as a part of single bvec.
>
> While there are other options such as huge_zero_page, they can fail
> based on the system memory pressure requiring a fallback to ZERO_PAGE[3].

Instead of adding another one, why not have a config option that will 
always allocate the huge zeropage, and never free it?

I mean, the whole thing about dynamically allocating/freeing it was for 
memory-constrained systems. For large systems, we just don't care.

--
Cheers,

David / dhildenb