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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
b0d40c92 DC |
2 | #ifndef _LINUX_SHRINKER_H |
3 | #define _LINUX_SHRINKER_H | |
4 | ||
5 | /* | |
6 | * This struct is used to pass information from page reclaim to the shrinkers. | |
06c88398 | 7 | * We consolidate the values for easier extension later. |
24f7c6b9 DC |
8 | * |
9 | * The 'gfpmask' refers to the allocation we are currently trying to | |
10 | * fulfil. | |
b0d40c92 DC |
11 | */ |
12 | struct shrink_control { | |
13 | gfp_t gfp_mask; | |
14 | ||
92be775a KT |
15 | /* current node being shrunk (for NUMA aware shrinkers) */ |
16 | int nid; | |
17 | ||
a0b02131 DC |
18 | /* |
19 | * How many objects scan_objects should scan and try to reclaim. | |
20 | * This is reset before every call, so it is safe for callees | |
21 | * to modify. | |
22 | */ | |
b0d40c92 | 23 | unsigned long nr_to_scan; |
0ce3d744 | 24 | |
d460acb5 CW |
25 | /* |
26 | * How many objects did scan_objects process? | |
27 | * This defaults to nr_to_scan before every call, but the callee | |
28 | * should track its actual progress. | |
29 | */ | |
30 | unsigned long nr_scanned; | |
31 | ||
cb731d6c VD |
32 | /* current memcg being shrunk (for memcg aware shrinkers) */ |
33 | struct mem_cgroup *memcg; | |
b0d40c92 DC |
34 | }; |
35 | ||
24f7c6b9 | 36 | #define SHRINK_STOP (~0UL) |
9b996468 | 37 | #define SHRINK_EMPTY (~0UL - 1) |
b0d40c92 DC |
38 | /* |
39 | * A callback you can register to apply pressure to ageable caches. | |
40 | * | |
24f7c6b9 | 41 | * @count_objects should return the number of freeable items in the cache. If |
9b996468 KT |
42 | * there are no objects to free, it should return SHRINK_EMPTY, while 0 is |
43 | * returned in cases of the number of freeable items cannot be determined | |
44 | * or shrinker should skip this cache for this time (e.g., their number | |
45 | * is below shrinkable limit). No deadlock checks should be done during the | |
24f7c6b9 DC |
46 | * count callback - the shrinker relies on aggregating scan counts that couldn't |
47 | * be executed due to potential deadlocks to be run at a later call when the | |
48 | * deadlock condition is no longer pending. | |
b0d40c92 | 49 | * |
24f7c6b9 DC |
50 | * @scan_objects will only be called if @count_objects returned a non-zero |
51 | * value for the number of freeable objects. The callout should scan the cache | |
52 | * and attempt to free items from the cache. It should then return the number | |
53 | * of objects freed during the scan, or SHRINK_STOP if progress cannot be made | |
54 | * due to potential deadlocks. If SHRINK_STOP is returned, then no further | |
55 | * attempts to call the @scan_objects will be made from the current reclaim | |
56 | * context. | |
1d3d4437 GC |
57 | * |
58 | * @flags determine the shrinker abilities, like numa awareness | |
b0d40c92 DC |
59 | */ |
60 | struct shrinker { | |
24f7c6b9 DC |
61 | unsigned long (*count_objects)(struct shrinker *, |
62 | struct shrink_control *sc); | |
63 | unsigned long (*scan_objects)(struct shrinker *, | |
64 | struct shrink_control *sc); | |
65 | ||
b0d40c92 | 66 | long batch; /* reclaim batch size, 0 = default */ |
e50ef89b KT |
67 | int seeks; /* seeks to recreate an obj */ |
68 | unsigned flags; | |
b0d40c92 DC |
69 | |
70 | /* These are for internal use */ | |
71 | struct list_head list; | |
0a432dcb | 72 | #ifdef CONFIG_MEMCG |
b4c2b231 KT |
73 | /* ID in shrinker_idr */ |
74 | int id; | |
75 | #endif | |
1d3d4437 GC |
76 | /* objs pending delete, per node */ |
77 | atomic_long_t *nr_deferred; | |
b0d40c92 DC |
78 | }; |
79 | #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ | |
1d3d4437 GC |
80 | |
81 | /* Flags */ | |
41ca668a YS |
82 | #define SHRINKER_REGISTERED (1 << 0) |
83 | #define SHRINKER_NUMA_AWARE (1 << 1) | |
84 | #define SHRINKER_MEMCG_AWARE (1 << 2) | |
0a432dcb YS |
85 | /* |
86 | * It just makes sense when the shrinker is also MEMCG_AWARE for now, | |
87 | * non-MEMCG_AWARE shrinker should not have this flag set. | |
88 | */ | |
41ca668a | 89 | #define SHRINKER_NONSLAB (1 << 3) |
1d3d4437 | 90 | |
8e04944f TH |
91 | extern int prealloc_shrinker(struct shrinker *shrinker); |
92 | extern void register_shrinker_prepared(struct shrinker *shrinker); | |
93 | extern int register_shrinker(struct shrinker *shrinker); | |
94 | extern void unregister_shrinker(struct shrinker *shrinker); | |
95 | extern void free_prealloced_shrinker(struct shrinker *shrinker); | |
b0d40c92 | 96 | #endif |