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95 lines
3.2 KiB
95 lines
3.2 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _LINUX_SHRINKER_H |
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#define _LINUX_SHRINKER_H |
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/* |
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* This struct is used to pass information from page reclaim to the shrinkers. |
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* We consolidate the values for easier extention later. |
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* |
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* The 'gfpmask' refers to the allocation we are currently trying to |
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* fulfil. |
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*/ |
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struct shrink_control { |
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gfp_t gfp_mask; |
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/* current node being shrunk (for NUMA aware shrinkers) */ |
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int nid; |
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/* |
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* How many objects scan_objects should scan and try to reclaim. |
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* This is reset before every call, so it is safe for callees |
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* to modify. |
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*/ |
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unsigned long nr_to_scan; |
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/* |
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* How many objects did scan_objects process? |
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* This defaults to nr_to_scan before every call, but the callee |
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* should track its actual progress. |
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*/ |
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unsigned long nr_scanned; |
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/* current memcg being shrunk (for memcg aware shrinkers) */ |
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struct mem_cgroup *memcg; |
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}; |
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#define SHRINK_STOP (~0UL) |
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#define SHRINK_EMPTY (~0UL - 1) |
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/* |
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* A callback you can register to apply pressure to ageable caches. |
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* |
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* @count_objects should return the number of freeable items in the cache. If |
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* there are no objects to free, it should return SHRINK_EMPTY, while 0 is |
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* returned in cases of the number of freeable items cannot be determined |
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* or shrinker should skip this cache for this time (e.g., their number |
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* is below shrinkable limit). No deadlock checks should be done during the |
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* count callback - the shrinker relies on aggregating scan counts that couldn't |
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* be executed due to potential deadlocks to be run at a later call when the |
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* deadlock condition is no longer pending. |
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* |
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* @scan_objects will only be called if @count_objects returned a non-zero |
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* value for the number of freeable objects. The callout should scan the cache |
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* and attempt to free items from the cache. It should then return the number |
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* of objects freed during the scan, or SHRINK_STOP if progress cannot be made |
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* due to potential deadlocks. If SHRINK_STOP is returned, then no further |
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* attempts to call the @scan_objects will be made from the current reclaim |
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* context. |
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* |
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* @flags determine the shrinker abilities, like numa awareness |
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*/ |
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struct shrinker { |
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unsigned long (*count_objects)(struct shrinker *, |
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struct shrink_control *sc); |
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unsigned long (*scan_objects)(struct shrinker *, |
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struct shrink_control *sc); |
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long batch; /* reclaim batch size, 0 = default */ |
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int seeks; /* seeks to recreate an obj */ |
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unsigned flags; |
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/* These are for internal use */ |
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struct list_head list; |
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#ifdef CONFIG_MEMCG |
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/* ID in shrinker_idr */ |
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int id; |
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#endif |
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/* objs pending delete, per node */ |
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atomic_long_t *nr_deferred; |
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}; |
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#define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ |
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/* Flags */ |
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#define SHRINKER_NUMA_AWARE (1 << 0) |
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#define SHRINKER_MEMCG_AWARE (1 << 1) |
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/* |
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* It just makes sense when the shrinker is also MEMCG_AWARE for now, |
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* non-MEMCG_AWARE shrinker should not have this flag set. |
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*/ |
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#define SHRINKER_NONSLAB (1 << 2) |
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extern int prealloc_shrinker(struct shrinker *shrinker); |
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extern void register_shrinker_prepared(struct shrinker *shrinker); |
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extern int register_shrinker(struct shrinker *shrinker); |
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extern void unregister_shrinker(struct shrinker *shrinker); |
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extern void free_prealloced_shrinker(struct shrinker *shrinker); |
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#endif
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