71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
#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.
|
|
*
|
|
* The 'gfpmask' refers to the allocation we are currently trying to
|
|
* fulfil.
|
|
*/
|
|
struct shrink_control {
|
|
gfp_t gfp_mask;
|
|
|
|
/*
|
|
* How many objects scan_objects should scan and try to reclaim.
|
|
* This is reset before every call, so it is safe for callees
|
|
* to modify.
|
|
*/
|
|
unsigned long nr_to_scan;
|
|
|
|
/* shrink from these nodes */
|
|
nodemask_t nodes_to_scan;
|
|
/* current node being shrunk (for NUMA aware shrinkers) */
|
|
int nid;
|
|
};
|
|
|
|
#define SHRINK_STOP (~0UL)
|
|
/*
|
|
* A callback you can register to apply pressure to ageable caches.
|
|
*
|
|
* @count_objects should return the number of freeable items in the cache. If
|
|
* there are no objects to free or the number of freeable items cannot be
|
|
* determined, it should return 0. No deadlock checks should be done during the
|
|
* count callback - the shrinker relies on aggregating scan counts that couldn't
|
|
* be executed due to potential deadlocks to be run at a later call when the
|
|
* deadlock condition is no longer pending.
|
|
*
|
|
* @scan_objects will only be called if @count_objects returned a non-zero
|
|
* value for the number of freeable objects. The callout should scan the cache
|
|
* and attempt to free items from the cache. It should then return the number
|
|
* of objects freed during the scan, or SHRINK_STOP if progress cannot be made
|
|
* due to potential deadlocks. If SHRINK_STOP is returned, then no further
|
|
* attempts to call the @scan_objects will be made from the current reclaim
|
|
* context.
|
|
*
|
|
* @flags determine the shrinker abilities, like numa awareness
|
|
*/
|
|
struct shrinker {
|
|
unsigned long (*count_objects)(struct shrinker *,
|
|
struct shrink_control *sc);
|
|
unsigned long (*scan_objects)(struct shrinker *,
|
|
struct shrink_control *sc);
|
|
|
|
int seeks; /* seeks to recreate an obj */
|
|
long batch; /* reclaim batch size, 0 = default */
|
|
unsigned long flags;
|
|
|
|
/* These are for internal use */
|
|
struct list_head list;
|
|
/* objs pending delete, per node */
|
|
atomic_long_t *nr_deferred;
|
|
};
|
|
#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
|
|
|
|
/* Flags */
|
|
#define SHRINKER_NUMA_AWARE (1 << 0)
|
|
|
|
extern int register_shrinker(struct shrinker *);
|
|
extern void unregister_shrinker(struct shrinker *);
|
|
#endif
|