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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - include/linux/shrinker.h
1 #ifndef _LINUX_SHRINKER_H
2 #define _LINUX_SHRINKER_H
5 * This struct is used to pass information from page reclaim to the shrinkers.
6 * We consolidate the values for easier extention later.
8 * The 'gfpmask' refers to the allocation we are currently trying to
11 struct shrink_control
{
15 * How many objects scan_objects should scan and try to reclaim.
16 * This is reset before every call, so it is safe for callees
19 unsigned long nr_to_scan
;
21 /* current node being shrunk (for NUMA aware shrinkers) */
24 /* current memcg being shrunk (for memcg aware shrinkers) */
25 struct mem_cgroup
*memcg
;
28 #define SHRINK_STOP (~0UL)
30 * A callback you can register to apply pressure to ageable caches.
32 * @count_objects should return the number of freeable items in the cache. If
33 * there are no objects to free or the number of freeable items cannot be
34 * determined, it should return 0. No deadlock checks should be done during the
35 * count callback - the shrinker relies on aggregating scan counts that couldn't
36 * be executed due to potential deadlocks to be run at a later call when the
37 * deadlock condition is no longer pending.
39 * @scan_objects will only be called if @count_objects returned a non-zero
40 * value for the number of freeable objects. The callout should scan the cache
41 * and attempt to free items from the cache. It should then return the number
42 * of objects freed during the scan, or SHRINK_STOP if progress cannot be made
43 * due to potential deadlocks. If SHRINK_STOP is returned, then no further
44 * attempts to call the @scan_objects will be made from the current reclaim
47 * @flags determine the shrinker abilities, like numa awareness
50 unsigned long (*count_objects
)(struct shrinker
*,
51 struct shrink_control
*sc
);
52 unsigned long (*scan_objects
)(struct shrinker
*,
53 struct shrink_control
*sc
);
55 int seeks
; /* seeks to recreate an obj */
56 long batch
; /* reclaim batch size, 0 = default */
59 /* These are for internal use */
60 struct list_head list
;
61 /* objs pending delete, per node */
62 atomic_long_t
*nr_deferred
;
64 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
67 #define SHRINKER_NUMA_AWARE (1 << 0)
68 #define SHRINKER_MEMCG_AWARE (1 << 1)
70 extern int register_shrinker(struct shrinker
*);
71 extern void unregister_shrinker(struct shrinker
*);