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Diffstat (limited to 'include/linux/shrinker.h')
| -rw-r--r-- | include/linux/shrinker.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h new file mode 100644 index 000000000000..790651b4e5ba --- /dev/null +++ b/include/linux/shrinker.h @@ -0,0 +1,42 @@ +#ifndef _LINUX_SHRINKER_H +#define _LINUX_SHRINKER_H + +/* + * This struct is used to pass information from page reclaim to the shrinkers. + * We consolidate the values for easier extention later. + */ +struct shrink_control { + gfp_t gfp_mask; + + /* How many slab objects shrinker() should scan and try to reclaim */ + unsigned long nr_to_scan; +}; + +/* + * A callback you can register to apply pressure to ageable caches. + * + * 'sc' is passed shrink_control which includes a count 'nr_to_scan' + * and a 'gfpmask'. It should look through the least-recently-used + * 'nr_to_scan' entries and attempt to free them up. It should return + * the number of objects which remain in the cache. If it returns -1, it means + * it cannot do any scanning at this time (eg. there is a risk of deadlock). + * + * The 'gfpmask' refers to the allocation we are currently trying to + * fulfil. + * + * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is + * querying the cache size, so a fastpath for that case is appropriate. + */ +struct shrinker { + int (*shrink)(struct shrinker *, struct shrink_control *sc); + int seeks; /* seeks to recreate an obj */ + long batch; /* reclaim batch size, 0 = default */ + + /* These are for internal use */ + struct list_head list; + long nr; /* objs pending delete */ +}; +#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ +extern void register_shrinker(struct shrinker *); +extern void unregister_shrinker(struct shrinker *); +#endif |