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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161/* 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 extension later. * * The 'gfpmask' refers to the allocation we are currently trying to * fulfil. */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 * to modify. */ unsigned long nr_to_scan;
/* * 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, 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. * * @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);
long batch; /* reclaim batch size, 0 = default */ 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. */
/* Internal flags */#define SHRINKER_REGISTERED BIT(0)#define SHRINKER_ALLOCATED BIT(1)
/* 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_DEBUGextern 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 */