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include/linux/shrinker.h
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#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. |
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* * The 'gfpmask' refers to the allocation we are currently trying to * fulfil. |
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*/ struct shrink_control { gfp_t gfp_mask; |
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/* * 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. */ |
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unsigned long nr_to_scan; |
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/* current node being shrunk (for NUMA aware shrinkers) */ int nid; |
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/* current memcg being shrunk (for memcg aware shrinkers) */ struct mem_cgroup *memcg; |
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}; |
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#define SHRINK_STOP (~0UL) |
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/* * A callback you can register to apply pressure to ageable caches. * |
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* @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. |
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* |
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* @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. |
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* * @flags determine the shrinker abilities, like numa awareness |
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*/ struct shrinker { |
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unsigned long (*count_objects)(struct shrinker *, struct shrink_control *sc); unsigned long (*scan_objects)(struct shrinker *, struct shrink_control *sc); |
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int seeks; /* seeks to recreate an obj */ long batch; /* reclaim batch size, 0 = default */ |
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unsigned long flags; |
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/* These are for internal use */ struct list_head list; |
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/* objs pending delete, per node */ atomic_long_t *nr_deferred; |
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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) #define SHRINKER_MEMCG_AWARE (1 << 1) |
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extern int register_shrinker(struct shrinker *); |
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extern void unregister_shrinker(struct shrinker *); #endif |