Re: [PATCH 2/2] Filter unevictable page out in deactivate_page

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> It's pointless that deactive_page's pagevec operation about
> unevictable page as it's nop.
> This patch removes unnecessary overhead which might be a bit problem
> in case that there are many unevictable page in system(ex, mprotect workload)
> 
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> ---
>  mm/swap.c |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/swap.c b/mm/swap.c
> index 2e9656d..b707694 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -511,6 +511,15 @@ static void drain_cpu_pagevecs(int cpu)
>   */
>  void deactivate_page(struct page *page)
>  {
> +
> +	/*
> +	 * In workload which system has many unevictable page(ex, mprotect),
> +	 * unevictalge page deactivation for accelerating reclaim
> +	 * is pointless.
> +	 */
> +	if (PageUnevictable(page))
> +		return;
> +

	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>


btw, I think we should check PageLRU too.