linux/mm/slab.h
Vladimir Davydov f7ce3190c4 slab: embed memcg_cache_params to kmem_cache
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>
2015-02-12 18:54:09 -08:00

364 lines
9.9 KiB
C

#ifndef MM_SLAB_H
#define MM_SLAB_H
/*
* Internal slab definitions
*/
#ifdef CONFIG_SLOB
/*
* Common fields provided in kmem_cache by all slab allocators
* This struct is either used directly by the allocator (SLOB)
* or the allocator must include definitions for all fields
* provided in kmem_cache_common in their definition of kmem_cache.
*
* Once we can do anonymous structs (C11 standard) we could put a
* anonymous struct definition in these allocators so that the
* separate allocations in the kmem_cache structure of SLAB and
* SLUB is no longer needed.
*/
struct kmem_cache {
unsigned int object_size;/* The original size of the object */
unsigned int size; /* The aligned/padded/added on size */
unsigned int align; /* Alignment as calculated */
unsigned long flags; /* Active flags on the slab */
const char *name; /* Slab name for sysfs */
int refcount; /* Use counter */
void (*ctor)(void *); /* Called on object slot creation */
struct list_head list; /* List of all slab caches on the system */
};
#endif /* CONFIG_SLOB */
#ifdef CONFIG_SLAB
#include <linux/slab_def.h>
#endif
#ifdef CONFIG_SLUB
#include <linux/slub_def.h>
#endif
#include <linux/memcontrol.h>
/*
* State of the slab allocator.
*
* This is used to describe the states of the allocator during bootup.
* Allocators use this to gradually bootstrap themselves. Most allocators
* have the problem that the structures used for managing slab caches are
* allocated from slab caches themselves.
*/
enum slab_state {
DOWN, /* No slab functionality yet */
PARTIAL, /* SLUB: kmem_cache_node available */
PARTIAL_NODE, /* SLAB: kmalloc size for node struct available */
UP, /* Slab caches usable but not all extras yet */
FULL /* Everything is working */
};
extern enum slab_state slab_state;
/* The slab cache mutex protects the management structures during changes */
extern struct mutex slab_mutex;
/* The list of all slab caches on the system */
extern struct list_head slab_caches;
/* The slab cache that manages slab cache information */
extern struct kmem_cache *kmem_cache;
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size);
#ifndef CONFIG_SLOB
/* Kmalloc array related functions */
void create_kmalloc_caches(unsigned long);
/* Find the kmalloc slab corresponding for a certain size */
struct kmem_cache *kmalloc_slab(size_t, gfp_t);
#endif
/* Functions provided by the slab allocators */
extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);
extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
unsigned long flags);
extern void create_boot_cache(struct kmem_cache *, const char *name,
size_t size, unsigned long flags);
int slab_unmergeable(struct kmem_cache *s);
struct kmem_cache *find_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *));
#ifndef CONFIG_SLOB
struct kmem_cache *
__kmem_cache_alias(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *));
unsigned long kmem_cache_flags(unsigned long object_size,
unsigned long flags, const char *name,
void (*ctor)(void *));
#else
static inline struct kmem_cache *
__kmem_cache_alias(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{ return NULL; }
static inline unsigned long kmem_cache_flags(unsigned long object_size,
unsigned long flags, const char *name,
void (*ctor)(void *))
{
return flags;
}
#endif
/* Legal flag mask for kmem_cache_create(), for various configurations */
#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )
#if defined(CONFIG_DEBUG_SLAB)
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
#elif defined(CONFIG_SLUB_DEBUG)
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_DEBUG_FREE)
#else
#define SLAB_DEBUG_FLAGS (0)
#endif
#if defined(CONFIG_SLAB)
#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | SLAB_NOTRACK)
#elif defined(CONFIG_SLUB)
#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
SLAB_TEMPORARY | SLAB_NOTRACK)
#else
#define SLAB_CACHE_FLAGS (0)
#endif
#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
int __kmem_cache_shutdown(struct kmem_cache *);
int __kmem_cache_shrink(struct kmem_cache *);
void slab_kmem_cache_release(struct kmem_cache *);
struct seq_file;
struct file;
struct slabinfo {
unsigned long active_objs;
unsigned long num_objs;
unsigned long active_slabs;
unsigned long num_slabs;
unsigned long shared_avail;
unsigned int limit;
unsigned int batchcount;
unsigned int shared;
unsigned int objects_per_slab;
unsigned int cache_order;
};
void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos);
#ifdef CONFIG_MEMCG_KMEM
static inline bool is_root_cache(struct kmem_cache *s)
{
return s->memcg_params.is_root_cache;
}
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
return p == s || p == s->memcg_params.root_cache;
}
/*
* We use suffixes to the name in memcg because we can't have caches
* created in the system with the same name. But when we print them
* locally, better refer to them with the base name
*/
static inline const char *cache_name(struct kmem_cache *s)
{
if (!is_root_cache(s))
s = s->memcg_params.root_cache;
return s->name;
}
/*
* Note, we protect with RCU only the memcg_caches array, not per-memcg caches.
* That said the caller must assure the memcg's cache won't go away by either
* taking a css reference to the owner cgroup, or holding the slab_mutex.
*/
static inline struct kmem_cache *
cache_from_memcg_idx(struct kmem_cache *s, int idx)
{
struct kmem_cache *cachep;
struct memcg_cache_array *arr;
rcu_read_lock();
arr = rcu_dereference(s->memcg_params.memcg_caches);
/*
* Make sure we will access the up-to-date value. The code updating
* memcg_caches issues a write barrier to match this (see
* memcg_create_kmem_cache()).
*/
cachep = lockless_dereference(arr->entries[idx]);
rcu_read_unlock();
return cachep;
}
static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
{
if (is_root_cache(s))
return s;
return s->memcg_params.root_cache;
}
static __always_inline int memcg_charge_slab(struct kmem_cache *s,
gfp_t gfp, int order)
{
if (!memcg_kmem_enabled())
return 0;
if (is_root_cache(s))
return 0;
return memcg_charge_kmem(s->memcg_params.memcg, gfp, 1 << order);
}
static __always_inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
{
if (!memcg_kmem_enabled())
return;
if (is_root_cache(s))
return;
memcg_uncharge_kmem(s->memcg_params.memcg, 1 << order);
}
extern void slab_init_memcg_params(struct kmem_cache *);
#else /* !CONFIG_MEMCG_KMEM */
static inline bool is_root_cache(struct kmem_cache *s)
{
return true;
}
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
return true;
}
static inline const char *cache_name(struct kmem_cache *s)
{
return s->name;
}
static inline struct kmem_cache *
cache_from_memcg_idx(struct kmem_cache *s, int idx)
{
return NULL;
}
static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
{
return s;
}
static inline int memcg_charge_slab(struct kmem_cache *s, gfp_t gfp, int order)
{
return 0;
}
static inline void memcg_uncharge_slab(struct kmem_cache *s, int order)
{
}
static inline void slab_init_memcg_params(struct kmem_cache *s)
{
}
#endif /* CONFIG_MEMCG_KMEM */
static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
{
struct kmem_cache *cachep;
struct page *page;
/*
* When kmemcg is not being used, both assignments should return the
* same value. but we don't want to pay the assignment price in that
* case. If it is not compiled in, the compiler should be smart enough
* to not do even the assignment. In that case, slab_equal_or_root
* will also be a constant.
*/
if (!memcg_kmem_enabled() && !unlikely(s->flags & SLAB_DEBUG_FREE))
return s;
page = virt_to_head_page(x);
cachep = page->slab_cache;
if (slab_equal_or_root(cachep, s))
return cachep;
pr_err("%s: Wrong slab cache. %s but object is from %s\n",
__func__, cachep->name, s->name);
WARN_ON_ONCE(1);
return s;
}
#ifndef CONFIG_SLOB
/*
* The slab lists for all objects.
*/
struct kmem_cache_node {
spinlock_t list_lock;
#ifdef CONFIG_SLAB
struct list_head slabs_partial; /* partial list first, better asm code */
struct list_head slabs_full;
struct list_head slabs_free;
unsigned long free_objects;
unsigned int free_limit;
unsigned int colour_next; /* Per-node cache coloring */
struct array_cache *shared; /* shared per node */
struct alien_cache **alien; /* on other nodes */
unsigned long next_reap; /* updated without locking */
int free_touched; /* updated without locking */
#endif
#ifdef CONFIG_SLUB
unsigned long nr_partial;
struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
#endif
};
static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
{
return s->node[node];
}
/*
* Iterator over all nodes. The body will be executed for each node that has
* a kmem_cache_node structure allocated (which is true for all online nodes)
*/
#define for_each_kmem_cache_node(__s, __node, __n) \
for (__node = 0; __node < nr_node_ids; __node++) \
if ((__n = get_node(__s, __node)))
#endif
void *slab_start(struct seq_file *m, loff_t *pos);
void *slab_next(struct seq_file *m, void *p, loff_t *pos);
void slab_stop(struct seq_file *m, void *p);
int memcg_slab_show(struct seq_file *m, void *p);
#endif /* MM_SLAB_H */