cregit-Linux how code gets into the kernel

Release 4.12 include/linux/shrinker.h

Directory: include/linux


 * This struct is used to pass information from page reclaim to the shrinkers.
 * We consolidate the values for easier extention later.
 * The 'gfpmask' refers to the allocation we are currently trying to
 * fulfil.

struct shrink_control {
gfp_t gfp_mask;

         * 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;

	/* current node being shrunk (for NUMA aware shrinkers) */
int nid;

	/* current memcg being shrunk (for memcg aware shrinkers) */
struct mem_cgroup *memcg;

#define SHRINK_STOP (~0UL)
 * 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
 * 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);

int seeks;	/* seeks to recreate an obj */
long batch;	/* reclaim batch size, 0 = default */
unsigned long flags;

	/* These are for internal use */
struct list_head list;
	/* 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)

extern int register_shrinker(struct shrinker *);
extern void unregister_shrinker(struct shrinker *);

Overall Contributors

Dave Chinner10278.46%350.00%
Glauber de Oliveira Costa1713.08%116.67%
Vladimir Davydov107.69%116.67%
Konstantin Khlebnikov10.77%116.67%
Directory: include/linux
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