Re: [PATCH] mm/zbud: init user ops only when it is needed

[Dan Streetman]

On Wed, Oct 15, 2014 at 6:00 AM, Heesub Shin <heesub.shin@xxxxxxxxxxx> wrote:
> When zbud is initialized through the zpool wrapper, pool->ops which
> points to user-defined operations is always set regardless of whether it
> is specified from the upper layer. This causes zbud_reclaim_page() to
> iterate its loop for evicting pool pages out without any gain.
>
> This patch sets the user-defined ops only when it is needed, so that
> zbud_reclaim_page() can bail out the reclamation loop earlier if there
> is no user-defined operations specified.

Though the only current user (zswap) always passes an ops param, other
future users may not and this is the right way to handle it.  thanks!

>
> Signed-off-by: Heesub Shin <heesub.shin@xxxxxxxxxxx>

Acked-by: Dan Streetman <ddstreet@xxxxxxxx>

> ---
>  mm/zbud.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/zbud.c b/mm/zbud.c
> index ecf1dbe..db8de74 100644
> --- a/mm/zbud.c
> +++ b/mm/zbud.c
> @@ -132,7 +132,7 @@ static struct zbud_ops zbud_zpool_ops = {
>
>  static void *zbud_zpool_create(gfp_t gfp, struct zpool_ops *zpool_ops)
>  {
> -       return zbud_create_pool(gfp, &zbud_zpool_ops);
> +       return zbud_create_pool(gfp, zpool_ops ? &zbud_zpool_ops : NULL);
>  }
>
>  static void zbud_zpool_destroy(void *pool)
> --
> 1.9.1
>
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