Re: [LSF/MM/BPF TOPIC] 64k (or 16k) base page size on x86

[David Laight]

On Mon, 23 Feb 2026 07:14:39 -0800
Dave Hansen <dave.hansen@xxxxxxxxx> wrote:

> On 2/23/26 03:27, David Hildenbrand (Arm) wrote:
> ...
> >> BTW, x86-64 SysV ABI allows for 64k page size:
> >>
> >>     Systems are permitted to use any power-of-two page size between
> >>     4KB and 64KB, inclusive.
> >>
> >> But it doesn't work in practice.  
> > 
> > Even in well controlled environments you would run in a hyperscaler?  
> 
> I think what Kirill is trying to say is that "it breaks userspace". ;)

With a 4k physical page what stops you dynamically splitting the 64k a
'struct page' references into 16 4k pages (using an extra dynamically
allocated structure)?
I'm not thinking it would happen that often, but it would solve the
problem of 4k aligned .data and (probably) mmap() of small files.

If the cpu supports TLB coalescing there could easily be a net gain
using 64k pages for most of a program binary.

	David