diff options
Diffstat (limited to 'include/linux/shrinker.h')
| -rw-r--r-- | include/linux/shrinker.h | 114 |
1 files changed, 101 insertions, 13 deletions
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 4fcacd915d45..1a00be90d93a 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -1,9 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_SHRINKER_H #define _LINUX_SHRINKER_H +#include <linux/atomic.h> +#include <linux/types.h> +#include <linux/refcount.h> +#include <linux/completion.h> + +#define SHRINKER_UNIT_BITS BITS_PER_LONG + +/* + * Bitmap and deferred work of shrinker::id corresponding to memcg-aware + * shrinkers, which have elements charged to the memcg. + */ +struct shrinker_info_unit { + atomic_long_t nr_deferred[SHRINKER_UNIT_BITS]; + DECLARE_BITMAP(map, SHRINKER_UNIT_BITS); +}; + +struct shrinker_info { + struct rcu_head rcu; + int map_nr_max; + struct shrinker_info_unit *unit[]; +}; + /* * This struct is used to pass information from page reclaim to the shrinkers. - * We consolidate the values for easier extention later. + * We consolidate the values for easier extension later. * * The 'gfpmask' refers to the allocation we are currently trying to * fulfil. @@ -11,6 +34,9 @@ struct shrink_control { gfp_t gfp_mask; + /* current node being shrunk (for NUMA aware shrinkers) */ + int nid; + /* * How many objects scan_objects should scan and try to reclaim. * This is reset before every call, so it is safe for callees @@ -18,20 +44,27 @@ struct shrink_control { */ unsigned long nr_to_scan; - /* current node being shrunk (for NUMA aware shrinkers) */ - int nid; + /* + * How many objects did scan_objects process? + * This defaults to nr_to_scan before every call, but the callee + * should track its actual progress. + */ + unsigned long nr_scanned; /* current memcg being shrunk (for memcg aware shrinkers) */ struct mem_cgroup *memcg; }; #define SHRINK_STOP (~0UL) +#define SHRINK_EMPTY (~0UL - 1) /* * 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 + * there are no objects to free, it should return SHRINK_EMPTY, while 0 is + * returned in cases of the number of freeable items cannot be determined + * or shrinker should skip this cache for this time (e.g., their number + * is below shrinkable limit). 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. @@ -52,21 +85,76 @@ struct shrinker { 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; + int seeks; /* seeks to recreate an obj */ + unsigned flags; + + /* + * The reference count of this shrinker. Registered shrinker have an + * initial refcount of 1, then the lookup operations are now allowed + * to use it via shrinker_try_get(). Later in the unregistration step, + * the initial refcount will be discarded, and will free the shrinker + * asynchronously via RCU after its refcount reaches 0. + */ + refcount_t refcount; + struct completion done; /* use to wait for refcount to reach 0 */ + struct rcu_head rcu; + + void *private_data; /* These are for internal use */ struct list_head list; +#ifdef CONFIG_MEMCG + /* ID in shrinker_idr */ + int id; +#endif +#ifdef CONFIG_SHRINKER_DEBUG + int debugfs_id; + const char *name; + struct dentry *debugfs_entry; +#endif /* 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) -#define SHRINKER_MEMCG_AWARE (1 << 1) +/* Internal flags */ +#define SHRINKER_REGISTERED BIT(0) +#define SHRINKER_ALLOCATED BIT(1) -extern int register_shrinker(struct shrinker *); -extern void unregister_shrinker(struct shrinker *); -#endif +/* Flags for users to use */ +#define SHRINKER_NUMA_AWARE BIT(2) +#define SHRINKER_MEMCG_AWARE BIT(3) +/* + * It just makes sense when the shrinker is also MEMCG_AWARE for now, + * non-MEMCG_AWARE shrinker should not have this flag set. + */ +#define SHRINKER_NONSLAB BIT(4) + +__printf(2, 3) +struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...); +void shrinker_register(struct shrinker *shrinker); +void shrinker_free(struct shrinker *shrinker); + +static inline bool shrinker_try_get(struct shrinker *shrinker) +{ + return refcount_inc_not_zero(&shrinker->refcount); +} + +static inline void shrinker_put(struct shrinker *shrinker) +{ + if (refcount_dec_and_test(&shrinker->refcount)) + complete(&shrinker->done); +} + +#ifdef CONFIG_SHRINKER_DEBUG +extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, + const char *fmt, ...); +#else /* CONFIG_SHRINKER_DEBUG */ +static inline __printf(2, 3) +int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) +{ + return 0; +} +#endif /* CONFIG_SHRINKER_DEBUG */ +#endif /* _LINUX_SHRINKER_H */ |