Re: [RFC PATCH 2/3] mm/mincore: Use can_pte_batch_count() in mincore_pte_range() for pte batch mincore_pte_range()

[David Hildenbrand]

On 27.10.25 15:03, Zhang Qilong wrote:
> In current mincore_pte_range(), if pte_batch_hint() return one
> pte, it's not efficient, just call new added can_pte_batch_count().
>
> In ARM64 qemu, with 8 CPUs, 32G memory, a simple test demo like:
> 1. mmap 1G anon memory
> 2. write 1G data by 4k step
> 3. mincore the mmaped 1G memory
> 4. get the time consumed by mincore
>
> Tested the following cases:
>   - 4k, disabled all hugepage setting.
>   - 64k mTHP, only enable 64k hugepage setting.
>
> Before
>
> Case status | Consumed time (us)  |
> ----------------------------------|
> 4k          | 7356                |
> 64k mTHP    | 3670                |
>
> Pathed:
>
> Case status | Consumed time (us)  |
> ----------------------------------|
> 4k          | 4419                |
> 64k mTHP    | 3061                |

I assume you're only lucky in that benchmark because you got consecutive 
4k pages / 64k mTHP from the buddy, right?

So I suspect that this will mostly just make a micro benchmark happy, 
because the reality where we allocate randomly over time, for the PCP, 
etc will look quite different.

--
Cheers

David / dhildenb