Re: [PATCH v3 2/2] mm/shmem: use xas_try_split() in shmem_split_large_entry()

[Baolin Wang]

On 2025/2/27 05:08, Zi Yan wrote:
> During shmem_split_large_entry(), large swap entries are covering n slots
> and an order-0 folio needs to be inserted.
>
> Instead of splitting all n slots, only the 1 slot covered by the folio
> need to be split and the remaining n-1 shadow entries can be retained with
> orders ranging from 0 to n-1.  This method only requires
> (n/XA_CHUNK_SHIFT) new xa_nodes instead of (n % XA_CHUNK_SHIFT) *
> (n/XA_CHUNK_SHIFT) new xa_nodes, compared to the original
> xas_split_alloc() + xas_split() one.
>
> For example, to split an order-9 large swap entry (assuming XA_CHUNK_SHIFT
> is 6), 1 xa_node is needed instead of 8.
>
> xas_try_split_min_order() is used to reduce the number of calls to
> xas_try_split() during split.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Kairui Song <kasong@xxxxxxxxxxx>
> Cc: Mattew Wilcox <willy@xxxxxxxxxxxxx>
> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> Cc: Kirill A. Shuemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
> Cc: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> > ---

LGTM. Feel free to add:
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>