On (09/12/17 11:37), Minchan Kim wrote:
[..]
> If rw-page based fast storage is used for swap devices, we need to
> detect it to enhance swap IO operations.
> This patch is preparation for optimizing of swap-in operation with
> next patch.
>
> Signed-off-by: Minchan Kim <minc...@kernel.org>
> ---
> include/linux/swap.h | 3 ++-
> mm/swapfile.c | 3 +++
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 8a807292037f..0f54b491e118 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -170,8 +170,9 @@ enum {
> SWP_AREA_DISCARD = (1 << 8), /* single-time swap area discards */
> SWP_PAGE_DISCARD = (1 << 9), /* freed swap page-cluster discards */
> SWP_STABLE_WRITES = (1 << 10), /* no overwrite PG_writeback pages */
> + SWP_SYNCHRONOUS_IO = (1<<11), /* synchronous IO is efficient */
a nitpick: (1 << 11)
-ss
> /* add others here before... */
> - SWP_SCANNING = (1 << 11), /* refcount in scan_swap_map */
> + SWP_SCANNING = (1 << 12), /* refcount in scan_swap_map */
> };
