Git Repo - linux.git/blame_incremental - include/linux/shrinker.h

... / ...

Commit	Line	Data
	1	#ifndef _LINUX_SHRINKER_H
	2	#define _LINUX_SHRINKER_H
	3
	4	/*
	5	* This struct is used to pass information from page reclaim to the shrinkers.
	6	* We consolidate the values for easier extention later.
	7	*/
	8	struct shrink_control {
	9	gfp_t gfp_mask;
	10
	11	/* How many slab objects shrinker() should scan and try to reclaim */
	12	unsigned long nr_to_scan;
	13	};
	14
	15	/*
	16	* A callback you can register to apply pressure to ageable caches.
	17	*
	18	* 'sc' is passed shrink_control which includes a count 'nr_to_scan'
	19	* and a 'gfpmask'. It should look through the least-recently-used
	20	* 'nr_to_scan' entries and attempt to free them up. It should return
	21	* the number of objects which remain in the cache. If it returns -1, it means
	22	* it cannot do any scanning at this time (eg. there is a risk of deadlock).
	23	* The callback must not return -1 if nr_to_scan is zero.
	24	*
	25	* The 'gfpmask' refers to the allocation we are currently trying to
	26	* fulfil.
	27	*
	28	* Note that 'shrink' will be passed nr_to_scan == 0 when the VM is
	29	* querying the cache size, so a fastpath for that case is appropriate.
	30	*/
	31	struct shrinker {
	32	int (shrink)(struct shrinker , struct shrink_control *sc);
	33	int seeks; /* seeks to recreate an obj */
	34	long batch; /* reclaim batch size, 0 = default */
	35
	36	/* These are for internal use */
	37	struct list_head list;
	38	atomic_long_t nr_in_batch; /* objs pending delete */
	39	};
	40	#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
	41	extern void register_shrinker(struct shrinker *);
	42	extern void unregister_shrinker(struct shrinker *);
	43	#endif