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Diffstat (limited to 'kern/slab.h')
| -rw-r--r-- | kern/slab.h | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/kern/slab.h b/kern/slab.h new file mode 100644 index 0000000..14c820b --- /dev/null +++ b/kern/slab.h @@ -0,0 +1,222 @@ +/* + * Copyright (c) 2009, 2010, 2011 Richard Braun. + * Copyright (c) 2011 Maksym Planeta. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef _KERN_SLAB_H +#define _KERN_SLAB_H + +#include <kern/lock.h> +#include <kern/list.h> +#include <kern/rbtree.h> +#include <mach/machine/vm_types.h> +#include <sys/types.h> +#include <vm/vm_types.h> + +#if SLAB_USE_CPU_POOLS +/* + * L1 cache line size. + */ +#define CPU_L1_SIZE (1 << CPU_L1_SHIFT) + +/* + * Per-processor cache of pre-constructed objects. + * + * The flags member is a read-only CPU-local copy of the parent cache flags. + */ +struct kmem_cpu_pool { + simple_lock_data_t lock; + int flags; + int size; + int transfer_size; + int nr_objs; + void **array; +} __attribute__((aligned(CPU_L1_SIZE))); + +/* + * When a cache is created, its CPU pool type is determined from the buffer + * size. For small buffer sizes, many objects can be cached in a CPU pool. + * Conversely, for large buffer sizes, this would incur much overhead, so only + * a few objects are stored in a CPU pool. + */ +struct kmem_cpu_pool_type { + size_t buf_size; + int array_size; + size_t array_align; + struct kmem_cache *array_cache; +}; +#endif /* SLAB_USE_CPU_POOLS */ + +/* + * Buffer descriptor. + * + * For normal caches (i.e. without SLAB_CF_VERIFY), bufctls are located at the + * end of (but inside) each buffer. If SLAB_CF_VERIFY is set, bufctls are + * located after each buffer. + * + * When an object is allocated to a client, its bufctl isn't used. This memory + * is instead used for redzoning if cache debugging is in effect. + */ +union kmem_bufctl { + union kmem_bufctl *next; + unsigned long redzone; +}; + +/* + * Buffer tag. + * + * This structure is only used for SLAB_CF_VERIFY caches. It is located after + * the bufctl and includes information about the state of the buffer it + * describes (allocated or not). It should be thought of as a debugging + * extension of the bufctl. + */ +struct kmem_buftag { + unsigned long state; +}; + +/* + * Page-aligned collection of unconstructed buffers. + */ +struct kmem_slab { + struct list list_node; + struct rbtree_node tree_node; + unsigned long nr_refs; + union kmem_bufctl *first_free; + void *addr; +}; + +/* + * Type for constructor functions. + * + * The pre-constructed state of an object is supposed to include only + * elements such as e.g. linked lists, locks, reference counters. Therefore + * constructors are expected to 1) never fail and 2) not need any + * user-provided data. The first constraint implies that object construction + * never performs dynamic resource allocation, which also means there is no + * need for destructors. + */ +typedef void (*kmem_cache_ctor_t)(void *obj); + +/* + * Types for slab allocation/free functions. + * + * All addresses and sizes must be page-aligned. + */ +typedef vm_offset_t (*kmem_slab_alloc_fn_t)(vm_size_t); +typedef void (*kmem_slab_free_fn_t)(vm_offset_t, vm_size_t); + +/* + * Cache name buffer size. + */ +#define KMEM_CACHE_NAME_SIZE 32 + +/* + * Cache of objects. + * + * Locking order : cpu_pool -> cache. CPU pools locking is ordered by CPU ID. + * + * The partial slabs list is sorted by slab references. Slabs with a high + * number of references are placed first on the list to reduce fragmentation. + * Sorting occurs at insertion/removal of buffers in a slab. As the list + * is maintained sorted, and the number of references only changes by one, + * this is a very cheap operation in the average case and the worst (linear) + * case is very unlikely. + */ +struct kmem_cache { +#if SLAB_USE_CPU_POOLS + /* CPU pool layer */ + struct kmem_cpu_pool cpu_pools[NCPUS]; + struct kmem_cpu_pool_type *cpu_pool_type; +#endif /* SLAB_USE_CPU_POOLS */ + + /* Slab layer */ + simple_lock_data_t lock; + struct list node; /* Cache list linkage */ + struct list partial_slabs; + struct list free_slabs; + struct rbtree active_slabs; + int flags; + size_t obj_size; /* User-provided size */ + size_t align; + size_t buf_size; /* Aligned object size */ + size_t bufctl_dist; /* Distance from buffer to bufctl */ + size_t slab_size; + size_t color; + size_t color_max; + unsigned long bufs_per_slab; + unsigned long nr_objs; /* Number of allocated objects */ + unsigned long nr_bufs; /* Total number of buffers */ + unsigned long nr_slabs; + unsigned long nr_free_slabs; + kmem_cache_ctor_t ctor; + kmem_slab_alloc_fn_t slab_alloc_fn; + kmem_slab_free_fn_t slab_free_fn; + char name[KMEM_CACHE_NAME_SIZE]; + size_t buftag_dist; /* Distance from buffer to buftag */ + size_t redzone_pad; /* Bytes from end of object to redzone word */ +}; + +/* + * Mach-style declarations for struct kmem_cache. + */ +typedef struct kmem_cache *kmem_cache_t; +#define KMEM_CACHE_NULL ((kmem_cache_t) 0) + +/* + * VM submap for slab allocations. + */ +extern vm_map_t kmem_map; + +/* + * Cache initialization flags. + */ +#define KMEM_CACHE_NOCPUPOOL 0x1 /* Don't use the per-cpu pools */ +#define KMEM_CACHE_NOOFFSLAB 0x2 /* Don't allocate external slab data */ +#define KMEM_CACHE_NORECLAIM 0x4 /* Never give slabs back to their source, + implies KMEM_CACHE_NOOFFSLAB */ +#define KMEM_CACHE_VERIFY 0x8 /* Use debugging facilities */ + +/* + * Initialize a cache. + */ +void kmem_cache_init(struct kmem_cache *cache, const char *name, + size_t obj_size, size_t align, kmem_cache_ctor_t ctor, + kmem_slab_alloc_fn_t slab_alloc_fn, + kmem_slab_free_fn_t slab_free_fn, int flags); + +/* + * Allocate an object from a cache. + */ +vm_offset_t kmem_cache_alloc(struct kmem_cache *cache); + +/* + * Release an object to its cache. + */ +void kmem_cache_free(struct kmem_cache *cache, vm_offset_t obj); + +/* + * Initialize the memory allocator module. + */ +void slab_bootstrap(void); +void slab_init(void); + +/* + * Release free slabs to the VM system. + */ +void slab_collect(void); + +#endif /* _KERN_SLAB_H */ |