|
原文地址：http://bbs.chinaunix.net/thread-2020986-1-1.html 最近看了一下slab的内容。简单写了个结构分析。 大家看看。这里先感谢一下 hyl 和 Eric Xiao的帮助。 下面是正文： 主要数据结构: struct kmem_cache_s { /* 1) per-cpu data, touched during every alloc/free */ struct array_cache *array[NR_CPUS]; unsigned int batchcount; unsigned int limit; /* 2) touched by every alloc & free from the backend */ struct kmem_list3 lists; /* NUMA: kmem_3list_t *nodelists[MAX_NUMNODES] */ unsigned int objsize; unsigned int flags; /* constant flags */ unsigned int num; /* # of objs per slab */ unsigned int free_limit; /* upper limit of objects in the lists */ spinlock_t spinlock; /* 3) cache_grow/shrink */ /* order of pgs per slab (2^n) */ unsigned int gfporder; /* force GFP flags, e.g. GFP_DMA */ unsigned int gfpflags; size_t colour; /* cache colouring range */ unsigned int colour_off; /* colour offset */ unsigned int colour_next; /* cache colouring */ kmem_cache_t *slabp_cache; unsigned int slab_size; unsigned int dflags; /* dynamic flags */ /* constructor func */ void (*ctor)(void *, kmem_cache_t *, unsigned long); /* de-constructor func */ void (*dtor)(void *, kmem_cache_t *, unsigned long); /* 4) cache creation/removal */ const char *name; struct list_head next; /* 5) statistics */ #if STATS 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; atomic_t allochit; atomic_t allocmiss; atomic_t freehit; atomic_t freemiss; #endif #if DEBUG int dbghead; int reallen; #endif }; struct slab { struct list_head list; unsigned long colouroff; void *s_mem; /* including colour offset */ unsigned int inuse; /* num of objs active in slab */ kmem_bufctl_t free; }; struct kmem_list3 { 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; int free_touched; unsigned long next_reap; struct array_cache *shared; }; cache由 kmem_cache_t(struct kmem_cache_s) 来描述. slab 由 struct slab 来描述 objec 由 kmem_bufctl_t 来描述 所有的kmem_cache_t 组成链表 cache_chain.该链表由信号量 cache_chain_sem来进行访问保护: static struct semaphore cache_chain_sem; static struct list_head cache_chain; cache_chain 的第一个高速缓存是 cache_cache. 可以从名字看出来,这个是缓存的缓存.也就是说它存储的是其它缓存的缓存描述符. 高速缓存分为general 和 specific 两种. 对于general的高速缓存,就是cache_cache 和 13个 kmalloc caches. 其中这13个kmalloc caches 的大小呈几何分布:32,64, 128, ... 他们在malloc_sizes表中定义. specific 的高速缓存是由kmem_cache_create()来创建的. 在内核启动的时候,初始化函数kmem_cache_init()来初始化cache_chain. 实际上它创建了general的高速缓存并初始化相应的内容. 整个的cache_chain的情形如下图所示: |
相关文章：