Re: [RESEND PATCH] mm: align larger anonymous mappings on THP boundaries

[David Hildenbrand <david@redhat.com>]

On 07.05.24 13:34, David Hildenbrand wrote:
> On 07.05.24 13:26, Ryan Roberts wrote:
>> On 07/05/2024 12:14, Ryan Roberts wrote:
>>> On 07/05/2024 12:13, David Hildenbrand wrote:
>>>>
>>>>> https://github.com/intel/lmbench/blob/master/src/lat_mem_rd.c#L95
>>>>>
>>>>>> suggest. If you want to try something semi-randomly; it might be useful to rule
>>>>>> out the arm64 contpte feature. I don't see how that would be interacting here if
>>>>>> mTHP is disabled (is it?). But its new for 6.9 and arm64 only. Disable with
>>>>>> ARM64_CONTPTE (needs EXPERT) at compile time.
>>>>> I don't enabled mTHP, so it should be not related about ARM64_CONTPTE,
>>>>> but will have a try.
>>>>
>>>> cont-pte can get active if we're just lucky when allocating pages in the right
>>>> order, correct Ryan?
>>>
>>> No it shouldn't do; it requires the pages to be in the same folio.
> 
> Ah, my memory comes back. That's also important for folio_pte_batch() to
> currently work as expected I think. We could change that, though, and
> let cont-pte batch across folios.

Thinking about it (and trying to refresh my memories), access/dirty bits 
might be why we don't want to do that.

-- 
Cheers,

David / dhildenb