Le 15/11/2023 à 22:37, Andrew Morton a écrit :
On Wed, 15 Nov 2023 16:30:05 +0000 Ryan Roberts <ryan.roberts@xxxxxxx> wrote:
However, the primary motivation for this change is to reduce the number
of tlb maintenance operations that the arm64 backend has to perform
during fork
Do you have a feeling for how much performance improved due to this?
Are there other architectures which might similarly benefit? By
implementing ptep_set_wrprotects(), it appears. If so, what sort of
gains might they see?
I think powerpc 8xx would benefit.
We have 16k hugepages which are implemented with 4 identical PTE which
have the _PAGE_SPS bit set. _PAGE_SPS says it is a 16k page.
We have 512k hugepages which are implemented with 128 identical PTE
which have _PAGE_HUGE bit set. _PAGE_HUGE tells it is a 512k page.
FWIW, PMD size is 4M and there is no 4M page size so no way to implement
leaf PMD huge pages.
Christophe
