On Fri, Jul 14, 2023 at 10:17 AM Ryan Roberts [off-list ref] wrote:

arch_wants_pte_order() can be overridden by the arch to return the
preferred folio order for pte-mapped memory. This is useful as some
architectures (e.g. arm64) can coalesce TLB entries when the physical
memory is suitably contiguous.

The first user for this hint will be FLEXIBLE_THP, which aims to
allocate large folios for anonymous memory to reduce page faults and
other per-page operation costs.

Here we add the default implementation of the function, used when the
architecture does not define it, which returns -1, implying that the HW
has no preference. In this case, mm will choose it's own default order.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>

Reviewed-by: Yu Zhao <redacted>

Thanks: -1 actually is better than 0 (what I suggested) for the obvious reason.

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