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linux-next/include/linux/shrinker.h
Vladimir Davydov cb731d6c62 vmscan: per memory cgroup slab shrinkers
This patch adds SHRINKER_MEMCG_AWARE flag.  If a shrinker has this flag
set, it will be called per memory cgroup.  The memory cgroup to scan
objects from is passed in shrink_control->memcg.  If the memory cgroup
is NULL, a memcg aware shrinker is supposed to scan objects from the
global list.  Unaware shrinkers are only called on global pressure with
memcg=NULL.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:09 -08:00

73 lines
2.4 KiB
C

#ifndef _LINUX_SHRINKER_H
#define _LINUX_SHRINKER_H
/*
* 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 *);
#endif