blob: 07ceb97d53facc505bae4b489d3cae96bd7d4021 [file] [log] [blame]
* 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 callback must not return -1 if nr_to_scan is zero.
* 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;
atomic_long_t nr_in_batch; /* 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 *);