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0a432dcbeb
Currently shrinker is just allocated and can work when memcg kmem is enabled. But, THP deferred split shrinker is not slab shrinker, it doesn't make too much sense to have such shrinker depend on memcg kmem. It should be able to reclaim THP even though memcg kmem is disabled. Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker. When memcg kmem is disabled, just such shrinkers can be called in shrinking memcg slab. [yang.shi@linux.alibaba.com: add comment] Link: http://lkml.kernel.org/r/1566496227-84952-4-git-send-email-yang.shi@linux.alibaba.com Link: http://lkml.kernel.org/r/1565144277-36240-4-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
95 lines
3.2 KiB
C
95 lines
3.2 KiB
C
/* 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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