1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SHRINKER_H 2 #ifndef _LINUX_SHRINKER_H
3 #define _LINUX_SHRINKER_H 3 #define _LINUX_SHRINKER_H
4 4
5 #include <linux/atomic.h> <<
6 #include <linux/types.h> <<
7 #include <linux/refcount.h> <<
8 #include <linux/completion.h> <<
9 <<
10 #define SHRINKER_UNIT_BITS BITS_PER_LONG <<
11 <<
12 /* <<
13 * Bitmap and deferred work of shrinker::id co <<
14 * shrinkers, which have elements charged to t <<
15 */ <<
16 struct shrinker_info_unit { <<
17 atomic_long_t nr_deferred[SHRINKER_UNI <<
18 DECLARE_BITMAP(map, SHRINKER_UNIT_BITS <<
19 }; <<
20 <<
21 struct shrinker_info { <<
22 struct rcu_head rcu; <<
23 int map_nr_max; <<
24 struct shrinker_info_unit *unit[]; <<
25 }; <<
26 <<
27 /* 5 /*
28 * This struct is used to pass information fro 6 * This struct is used to pass information from page reclaim to the shrinkers.
29 * We consolidate the values for easier extens !! 7 * We consolidate the values for easier extention later.
30 * 8 *
31 * The 'gfpmask' refers to the allocation we a 9 * The 'gfpmask' refers to the allocation we are currently trying to
32 * fulfil. 10 * fulfil.
33 */ 11 */
34 struct shrink_control { 12 struct shrink_control {
35 gfp_t gfp_mask; 13 gfp_t gfp_mask;
36 14
37 /* current node being shrunk (for NUMA <<
38 int nid; <<
39 <<
40 /* 15 /*
41 * How many objects scan_objects shoul 16 * How many objects scan_objects should scan and try to reclaim.
42 * This is reset before every call, so 17 * This is reset before every call, so it is safe for callees
43 * to modify. 18 * to modify.
44 */ 19 */
45 unsigned long nr_to_scan; 20 unsigned long nr_to_scan;
46 21
47 /* 22 /*
48 * How many objects did scan_objects p 23 * How many objects did scan_objects process?
49 * This defaults to nr_to_scan before 24 * This defaults to nr_to_scan before every call, but the callee
50 * should track its actual progress. 25 * should track its actual progress.
51 */ 26 */
52 unsigned long nr_scanned; 27 unsigned long nr_scanned;
53 28
>> 29 /* current node being shrunk (for NUMA aware shrinkers) */
>> 30 int nid;
>> 31
54 /* current memcg being shrunk (for mem 32 /* current memcg being shrunk (for memcg aware shrinkers) */
55 struct mem_cgroup *memcg; 33 struct mem_cgroup *memcg;
56 }; 34 };
57 35
58 #define SHRINK_STOP (~0UL) 36 #define SHRINK_STOP (~0UL)
59 #define SHRINK_EMPTY (~0UL - 1) <<
60 /* 37 /*
61 * A callback you can register to apply pressu 38 * A callback you can register to apply pressure to ageable caches.
62 * 39 *
63 * @count_objects should return the number of 40 * @count_objects should return the number of freeable items in the cache. If
64 * there are no objects to free, it should ret !! 41 * there are no objects to free or the number of freeable items cannot be
65 * returned in cases of the number of freeable !! 42 * determined, it should return 0. No deadlock checks should be done during the
66 * or shrinker should skip this cache for this <<
67 * is below shrinkable limit). No deadlock che <<
68 * count callback - the shrinker relies on agg 43 * count callback - the shrinker relies on aggregating scan counts that couldn't
69 * be executed due to potential deadlocks to b 44 * be executed due to potential deadlocks to be run at a later call when the
70 * deadlock condition is no longer pending. 45 * deadlock condition is no longer pending.
71 * 46 *
72 * @scan_objects will only be called if @count 47 * @scan_objects will only be called if @count_objects returned a non-zero
73 * value for the number of freeable objects. T 48 * value for the number of freeable objects. The callout should scan the cache
74 * and attempt to free items from the cache. I 49 * and attempt to free items from the cache. It should then return the number
75 * of objects freed during the scan, or SHRINK 50 * of objects freed during the scan, or SHRINK_STOP if progress cannot be made
76 * due to potential deadlocks. If SHRINK_STOP 51 * due to potential deadlocks. If SHRINK_STOP is returned, then no further
77 * attempts to call the @scan_objects will be 52 * attempts to call the @scan_objects will be made from the current reclaim
78 * context. 53 * context.
79 * 54 *
80 * @flags determine the shrinker abilities, li 55 * @flags determine the shrinker abilities, like numa awareness
81 */ 56 */
82 struct shrinker { 57 struct shrinker {
83 unsigned long (*count_objects)(struct 58 unsigned long (*count_objects)(struct shrinker *,
84 struct 59 struct shrink_control *sc);
85 unsigned long (*scan_objects)(struct s 60 unsigned long (*scan_objects)(struct shrinker *,
86 struct s 61 struct shrink_control *sc);
87 62
88 long batch; /* reclaim batch size, <<
89 int seeks; /* seeks to recreate a 63 int seeks; /* seeks to recreate an obj */
90 unsigned flags; !! 64 long batch; /* reclaim batch size, 0 = default */
91 !! 65 unsigned long flags;
92 /* <<
93 * The reference count of this shrinke <<
94 * initial refcount of 1, then the loo <<
95 * to use it via shrinker_try_get(). L <<
96 * the initial refcount will be discar <<
97 * asynchronously via RCU after its re <<
98 */ <<
99 refcount_t refcount; <<
100 struct completion done; /* use to wait <<
101 struct rcu_head rcu; <<
102 <<
103 void *private_data; <<
104 66
105 /* These are for internal use */ 67 /* These are for internal use */
106 struct list_head list; 68 struct list_head list;
107 #ifdef CONFIG_MEMCG <<
108 /* ID in shrinker_idr */ <<
109 int id; <<
110 #endif <<
111 #ifdef CONFIG_SHRINKER_DEBUG <<
112 int debugfs_id; <<
113 const char *name; <<
114 struct dentry *debugfs_entry; <<
115 #endif <<
116 /* objs pending delete, per node */ 69 /* objs pending delete, per node */
117 atomic_long_t *nr_deferred; 70 atomic_long_t *nr_deferred;
118 }; 71 };
119 #define DEFAULT_SEEKS 2 /* A good number if yo 72 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
120 73
121 /* Internal flags */ !! 74 /* Flags */
122 #define SHRINKER_REGISTERED BIT(0) !! 75 #define SHRINKER_NUMA_AWARE (1 << 0)
123 #define SHRINKER_ALLOCATED BIT(1) !! 76 #define SHRINKER_MEMCG_AWARE (1 << 1)
124 !! 77
125 /* Flags for users to use */ !! 78 extern int prealloc_shrinker(struct shrinker *shrinker);
126 #define SHRINKER_NUMA_AWARE BIT(2) !! 79 extern void register_shrinker_prepared(struct shrinker *shrinker);
127 #define SHRINKER_MEMCG_AWARE BIT(3) !! 80 extern int register_shrinker(struct shrinker *shrinker);
128 /* !! 81 extern void unregister_shrinker(struct shrinker *shrinker);
129 * It just makes sense when the shrinker is al !! 82 extern void free_prealloced_shrinker(struct shrinker *shrinker);
130 * non-MEMCG_AWARE shrinker should not have th !! 83 #endif
131 */ <<
132 #define SHRINKER_NONSLAB BIT(4) <<
133 <<
134 __printf(2, 3) <<
135 struct shrinker *shrinker_alloc(unsigned int f <<
136 void shrinker_register(struct shrinker *shrink <<
137 void shrinker_free(struct shrinker *shrinker); <<
138 <<
139 static inline bool shrinker_try_get(struct shr <<
140 { <<
141 return refcount_inc_not_zero(&shrinker <<
142 } <<
143 <<
144 static inline void shrinker_put(struct shrinke <<
145 { <<
146 if (refcount_dec_and_test(&shrinker->r <<
147 complete(&shrinker->done); <<
148 } <<
149 <<
150 #ifdef CONFIG_SHRINKER_DEBUG <<
151 extern int __printf(2, 3) shrinker_debugfs_ren <<
152 <<
153 #else /* CONFIG_SHRINKER_DEBUG */ <<
154 static inline __printf(2, 3) <<
155 int shrinker_debugfs_rename(struct shrinker *s <<
156 { <<
157 return 0; <<
158 } <<
159 #endif /* CONFIG_SHRINKER_DEBUG */ <<
160 #endif /* _LINUX_SHRINKER_H */ <<
161 84
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