Re: [PATCH 2/3] change the shrink_slab by passing scan_control.

[Ying Han <yinghan@google.com>]

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On Tue, Apr 19, 2011 at 10:51 AM, Ying Han <yinghan@google.com> wrote:

> This patch consolidates existing parameters to shrink_slab() to
> scan_control struct. This is needed later to pass the same struct
> to shrinkers.
>
> Signed-off-by: Ying Han <yinghan@google.com>
> ---
>  fs/drop_caches.c   |    7 ++++++-
>  include/linux/mm.h |    4 ++--
>  mm/vmscan.c        |   12 ++++++------
>  3 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/fs/drop_caches.c b/fs/drop_caches.c
> index 816f88e..0e5ef62 100644
> --- a/fs/drop_caches.c
> +++ b/fs/drop_caches.c
> @@ -8,6 +8,7 @@
>  #include <linux/writeback.h>
>  #include <linux/sysctl.h>
>  #include <linux/gfp.h>
> +#include <linux/swap.h>
>
>  /* A global variable is a bit ugly, but it keeps the code simple */
>  int sysctl_drop_caches;
> @@ -36,9 +37,13 @@ static void drop_pagecache_sb(struct super_block *sb,
> void *unused)
>  static void drop_slab(void)
>  {
>        int nr_objects;
> +       struct scan_control sc = {
> +               .gfp_mask = GFP_KERNEL,
> +               .nr_scanned = 1000,
> +       };
>
>        do {
> -               nr_objects = shrink_slab(1000, GFP_KERNEL, 1000);
> +               nr_objects = shrink_slab(&sc, 1000);
>        } while (nr_objects > 10);
>  }
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0716517..42c2bf4 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -21,6 +21,7 @@ struct anon_vma;
>  struct file_ra_state;
>  struct user_struct;
>  struct writeback_control;
> +struct scan_control;
>
>  #ifndef CONFIG_DISCONTIGMEM          /* Don't use mapnrs, do it properly
> */
>  extern unsigned long max_mapnr;
> @@ -1601,8 +1602,7 @@ int in_gate_area_no_task(unsigned long addr);
>
>  int drop_caches_sysctl_handler(struct ctl_table *, int,
>                                        void __user *, size_t *, loff_t *);
> -unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
> -                       unsigned long lru_pages);
> +unsigned long shrink_slab(struct scan_control *sc, unsigned long
> lru_pages);
>
>  #ifndef CONFIG_MMU
>  #define randomize_va_space 0
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 08b1ab5..9662166 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -159,11 +159,12 @@ EXPORT_SYMBOL(unregister_shrinker);
>  *
>  * Returns the number of slab objects which we shrunk.
>  */
> -unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
> -                       unsigned long lru_pages)
> +unsigned long shrink_slab(struct scan_control *sc, unsigned long
> lru_pages)
>  {
>        struct shrinker *shrinker;
>        unsigned long ret = 0;
> +       unsigned long scanned = sc->nr_scanned;
> +       gfp_t gfp_mask = sc->gfp_mask;
>
>        if (scanned == 0)
>                scanned = SWAP_CLUSTER_MAX;
> @@ -2005,7 +2006,7 @@ static unsigned long do_try_to_free_pages(struct
> zonelist *zonelist,
>                                lru_pages += zone_reclaimable_pages(zone);
>                        }
>
> -                       shrink_slab(sc->nr_scanned, sc->gfp_mask,
> lru_pages);
> +                       shrink_slab(sc, lru_pages);
>                        if (reclaim_state) {
>                                sc->nr_reclaimed +=
> reclaim_state->reclaimed_slab;
>                                reclaim_state->reclaimed_slab = 0;
> @@ -2371,8 +2372,7 @@ loop_again:
>                                        end_zone, 0))
>                                shrink_zone(priority, zone, &sc);
>                        reclaim_state->reclaimed_slab = 0;
> -                       nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
> -                                               lru_pages);
> +                       nr_slab = shrink_slab(&sc, lru_pages);
>                        sc.nr_reclaimed += reclaim_state->reclaimed_slab;
>                        total_scanned += sc.nr_scanned;
>
> @@ -2949,7 +2949,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t
> gfp_mask, unsigned int order)
>                        unsigned long lru_pages =
> zone_reclaimable_pages(zone);
>
>                        /* No reclaimable slab or very low memory pressure
> */
> -                       if (!shrink_slab(sc.nr_scanned, gfp_mask,
> lru_pages))
> +                       if (!shrink_slab(&sc, lru_pages))
>                                break;
>
>                        /* Freed enough memory */
> --
> 1.7.3.1
>
>

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