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![Vladimir Davydov](/assets/img/avatar_default.png)
Currently, kmem_cache stores a pointer to struct memcg_cache_params instead of embedding it. The rationale is to save memory when kmem accounting is disabled. However, the memcg_cache_params has shrivelled drastically since it was first introduced: * Initially: struct memcg_cache_params { bool is_root_cache; union { struct kmem_cache *memcg_caches[0]; struct { struct mem_cgroup *memcg; struct list_head list; struct kmem_cache *root_cache; bool dead; atomic_t nr_pages; struct work_struct destroy; }; }; }; * Now: struct memcg_cache_params { bool is_root_cache; union { struct { struct rcu_head rcu_head; struct kmem_cache *memcg_caches[0]; }; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; }; }; }; So the memory saving does not seem to be a clear win anymore. OTOH, keeping a pointer to memcg_cache_params struct instead of embedding it results in touching one more cache line on kmem alloc/free hot paths. Besides, it makes linking kmem caches in a list chained by a field of struct memcg_cache_params really painful due to a level of indirection, while I want to make them linked in the following patch. That said, let us embed it. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Tejun Heo <tj@kernel.org> 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: Dave Chinner <david@fromorbit.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
#ifndef _LINUX_SLAB_DEF_H
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#define _LINUX_SLAB_DEF_H
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#include <linux/reciprocal_div.h>
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/*
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* Definitions unique to the original Linux SLAB allocator.
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*/
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struct kmem_cache {
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struct array_cache __percpu *cpu_cache;
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/* 1) Cache tunables. Protected by slab_mutex */
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unsigned int batchcount;
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unsigned int limit;
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unsigned int shared;
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unsigned int size;
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struct reciprocal_value reciprocal_buffer_size;
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/* 2) touched by every alloc & free from the backend */
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unsigned int flags; /* constant flags */
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unsigned int num; /* # of objs per slab */
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/* 3) cache_grow/shrink */
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/* order of pgs per slab (2^n) */
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unsigned int gfporder;
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/* force GFP flags, e.g. GFP_DMA */
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gfp_t allocflags;
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size_t colour; /* cache colouring range */
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unsigned int colour_off; /* colour offset */
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struct kmem_cache *freelist_cache;
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unsigned int freelist_size;
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/* constructor func */
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void (*ctor)(void *obj);
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/* 4) cache creation/removal */
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const char *name;
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struct list_head list;
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int refcount;
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int object_size;
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int align;
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/* 5) statistics */
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#ifdef CONFIG_DEBUG_SLAB
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unsigned long num_active;
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unsigned long num_allocations;
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unsigned long high_mark;
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unsigned long grown;
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unsigned long reaped;
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unsigned long errors;
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unsigned long max_freeable;
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unsigned long node_allocs;
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unsigned long node_frees;
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unsigned long node_overflow;
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atomic_t allochit;
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atomic_t allocmiss;
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atomic_t freehit;
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atomic_t freemiss;
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/*
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* If debugging is enabled, then the allocator can add additional
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* fields and/or padding to every object. size contains the total
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* object size including these internal fields, the following two
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* variables contain the offset to the user object and its size.
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*/
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int obj_offset;
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#endif /* CONFIG_DEBUG_SLAB */
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#ifdef CONFIG_MEMCG_KMEM
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struct memcg_cache_params memcg_params;
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#endif
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struct kmem_cache_node *node[MAX_NUMNODES];
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};
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#endif /* _LINUX_SLAB_DEF_H */
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