struct kmem_cache {
/* 1) per-cpu data, touched during every alloc/free */
/*per-CPU数据，记录了本地高速缓存的信息，也用于跟踪最近释放的对象，每次分配和释放都要直接访问它*/
struct array_cache *array[NR_CPUS];
/* 2) Cache tunables. Protected by cache_chain_mutex */
unsigned int batchcount; /*本地高速缓存转入或转出的大批对象数量*/
unsigned int limit; /*本地高速缓存中空闲对象的最大数目*/
unsigned int shared;
unsigned int buffer_size;/*管理对象的大小*/
u32 reciprocal_buffer_size;/*buffer_size的倒数值*/
/* 3) touched by every alloc & free from the backend */
unsigned int flags; /* 高速缓存的永久标识*/
unsigned int num; /* 一个slab所包含的对象数目 */
/* 4) cache_grow/shrink */
/* order of pgs per slab (2^n) */
unsigned int gfporder; /*一个slab包含的连续页框数的对数*/
/* force GFP flags, e.g. GFP_DMA */
gfp_t gfpflags; /*与伙伴系统交互时所提供的分配标识*/
size_t colour; /* 颜色的个数*/
unsigned int colour_off; /* 着色的偏移量 */
/*如果将slab描述符存储在外部，该指针指向存储slab描述符的cache,
否则为NULL*/
struct kmem_cache *slabp_cache;
unsigned int slab_size; /*slab管理区的大小*/
unsigned int dflags; /*动态标识*/
/* constructor func */
void (*ctor)(void *obj); /*创建高速缓存时的构造函数指针*/
/* 5) cache creation/removal */
const char *name; /*高速缓存名*/
struct list_head next; /*用于将高速缓存链入cache chain*/
/* 6) statistics */
#ifdef CONFIG_DEBUG_SLAB /*一些用于调试用的变量*/
unsigned long num_active;
unsigned long num_allocations;
unsigned long high_mark;
unsigned long grown;
unsigned long reaped;
unsigned long errors;
unsigned long max_freeable;
unsigned long node_allocs;
unsigned long node_frees;
unsigned long node_overflow;
atomic_t allochit;
atomic_t allocmiss;
atomic_t freehit;
atomic_t freemiss;
/*
* If debugging is enabled, then the allocator can add additional
* fields and/or padding to every object. buffer_size contains the total
* object size including these internal fields, the following two
* variables contain the offset to the user object and its size.
*/
int obj_offset;
int obj_size;
#endif /* CONFIG_DEBUG_SLAB */
/*
* We put nodelists[] at the end of kmem_cache, because we want to size
* this array to nr_node_ids slots instead of MAX_NUMNODES
* (see kmem_cache_init())
* We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
* is statically defined, so we reserve the max number of nodes.
*/
/*struct kmem_list3用于组织该高速缓存中的slab*/
struct kmem_list3 *nodelists[MAX_NUMNODES];
/*
* Do not add fields after nodelists[]
*/
};
12345678910111213
struct kmem_list3 {
struct list_head slabs_partial;/*slab链表，包含空闲对象和已分配对象的slab描述符*/
struct list_head slabs_full; /*slab链表，只包含非空闲的slab描述符*/
struct list_head slabs_free; /*slab链表，只包含空闲的slab描述符*/
unsigned long free_objects; /*高速缓存中空闲对象的个数*/
unsigned int free_limit; /*空闲对象的上限*/
unsigned int colour_next; /*下一个slab使用的颜色*/
spinlock_t list_lock;
struct array_cache *shared; /* shared per node */
struct array_cache **alien; /* on other nodes */
unsigned long next_reap; /* updated without locking */
int free_touched; /* updated without locking */
};
描述和管理单个slab的结构是struct slab
12345678
struct slab {
struct list_head list; /*用于将slab链入kmem_list3的链表*/
unsigned long colouroff;/*该slab的着色偏移*/
void *s_mem; /*指向slab中的第一个对象*/
unsigned int inuse; /*已分配出去的对象*/
kmem_bufctl_t free; /*下一个空闲对象的下标*/
unsigned short nodeid; /*节点标识号*/
};
