diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mm.h | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 97d0cddfd223..4c482a3ee870 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -810,27 +810,31 @@ extern unsigned long do_mremap(unsigned long addr, unsigned long flags, unsigned long new_addr); /* - * Prototype to add a shrinker callback for ageable caches. - * - * These functions are passed a count `nr_to_scan' and a gfpmask. They should - * scan `nr_to_scan' objects, attempting to free them. + * A callback you can register to apply pressure to ageable caches. * - * The callback must return the number of objects which remain in the cache. + * 'shrink' is passed 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 callback will be passed nr_to_scan == 0 when the VM is querying the - * cache size, so a fastpath for that case is appropriate. - */ -typedef int (*shrinker_t)(int nr_to_scan, gfp_t gfp_mask); - -/* - * Add an aging callback. The int is the number of 'seeks' it takes - * to recreate one of the objects that these functions age. + * 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)(int nr_to_scan, gfp_t gfp_mask); + int seeks; /* seeks to recreate an obj */ -#define DEFAULT_SEEKS 2 -struct shrinker; -extern struct shrinker *set_shrinker(int, shrinker_t); -extern void remove_shrinker(struct shrinker *shrinker); + /* 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 *); /* * Some shared mappigns will want the pages marked read-only |