freebsd-dev/sys/vm/uma_int.h
Jeff Roberson 8355f576a9 This is the first part of the new kernel memory allocator. This replaces
malloc(9) and vm_zone with a slab like allocator.

Reviewed by:	arch@
2002-03-19 09:11:49 +00:00

329 lines
12 KiB
C

/*
* Copyright (c) 2002, Jeffrey Roberson <jroberson@chesapeake.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*
*/
/*
*
* Jeff Roberson <jroberson@chesapeake.net>
*
* This file includes definitions, structures, prototypes, and inlines that
* should not be used outside of the actual implementation of UMA.
*
*/
/*
* Here's a quick description of the relationship between the objects:
*
* Zones contain lists of slabs which are stored in either the full bin, empty
* bin, or partially allocated bin, to reduce fragmentation. They also contain
* the user supplied value for size, which is adjusted for alignment purposes
* and rsize is the result of that. The zone also stores information for
* managing a hash of page addresses that maps pages to uma_slab_t structures
* for pages that don't have embedded uma_slab_t's.
*
* The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
* be allocated off the page from a special slab zone. The free list within a
* slab is managed with a linked list of indexes, which are 8 bit values. If
* UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
* values. Currently on alpha you can get 250 or so 32 byte items and on x86
* you can get 250 or so 16byte items. For item sizes that would yield more
* than 10% memory waste we potentially allocate a seperate uma_slab_t if this
* will improve the number of items per slab that will fit.
*
* Other potential space optimizations are storing the 8bit of linkage in space
* wasted between items due to alignment problems. This may yield a much better
* memory footprint for certain sizes of objects. Another alternative is to
* increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer
* dynamic slab sizes because we could stick with 8 bit indexes and only use
* large slab sizes for zones with a lot of waste per slab. This may create
* ineffeciencies in the vm subsystem due to fragmentation in the address space.
*
* The only really gross cases, with regards to memory waste, are for those
* items that are just over half the page size. You can get nearly 50% waste,
* so you fall back to the memory footprint of the power of two allocator. I
* have looked at memory allocation sizes on many of the machines available to
* me, and there does not seem to be an abundance of allocations at this range
* so at this time it may not make sense to optimize for it. This can, of
* course, be solved with dynamic slab sizes.
*
*/
/*
* This is the representation for normal (Non OFFPAGE slab)
*
* i == item
* s == slab pointer
*
* <---------------- Page (UMA_SLAB_SIZE) ------------------>
* ___________________________________________________________
* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ |
* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________||
* |___________________________________________________________|
*
*
* This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
*
* ___________________________________________________________
* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |
* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |
* |___________________________________________________________|
* ___________ ^
* |slab header| |
* |___________|---*
*
*/
#ifndef VM_UMA_INT_H
#define VM_UMA_INT_H
#include <sys/mutex.h>
#define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */
#define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */
#define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */
#define UMA_BOOT_PAGES 15 /* Number of pages allocated for startup */
#define UMA_WORKING_TIME 20 /* Seconds worth of items to keep */
/* Max waste before going to off page slab management */
#define UMA_MAX_WASTE (UMA_SLAB_SIZE / 10)
/*
* I doubt there will be many cases where this is exceeded. This is the initial
* size of the hash table for uma_slabs that are managed off page. This hash
* does expand by powers of two. Currently it doesn't get smaller.
*/
#define UMA_HASH_SIZE_INIT 32
/*
* I should investigate other hashing algorithms. This should yield a low
* number of collisions if the pages are relatively contiguous.
*
* This is the same algorithm that most processor caches use.
*
* I'm shifting and masking instead of % because it should be faster.
*/
#define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) & \
(h)->uh_hashmask)
#define UMA_HASH_INSERT(h, s, mem) \
SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \
(mem))], (s), us_hlink);
#define UMA_HASH_REMOVE(h, s, mem) \
SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \
(mem))], (s), uma_slab, us_hlink);
/* Page management structure */
/* Sorry for the union, but space efficiency is important */
struct uma_slab {
uma_zone_t us_zone; /* Zone we live in */
union {
LIST_ENTRY(uma_slab) us_link; /* slabs in zone */
unsigned long us_size; /* Size of allocation */
} us_type;
SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */
u_int8_t *us_data; /* First item */
u_int8_t us_flags; /* Page flags see uma.h */
u_int8_t us_freecount; /* How many are free? */
u_int8_t us_firstfree; /* First free item index */
u_int8_t us_freelist[1]; /* Free List (actually larger) */
};
#define us_link us_type.us_link
#define us_size us_type.us_size
typedef struct uma_slab * uma_slab_t;
/* Hash table for freed address -> slab translation */
SLIST_HEAD(slabhead, uma_slab);
struct uma_hash {
struct slabhead *uh_slab_hash; /* Hash table for slabs */
int uh_hashsize; /* Current size of the hash table */
int uh_hashmask; /* Mask used during hashing */
};
extern struct uma_hash *mallochash;
/*
* Structures for per cpu queues.
*/
/*
* This size was chosen so that the struct bucket size is roughly
* 128 * sizeof(void *). This is exactly true for x86, and for alpha
* it will would be 32bits smaller if it didn't have alignment adjustments.
*/
#define UMA_BUCKET_SIZE 125
struct uma_bucket {
LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */
int16_t ub_ptr; /* Pointer to current item */
void *ub_bucket[UMA_BUCKET_SIZE]; /* actual allocation storage */
};
typedef struct uma_bucket * uma_bucket_t;
struct uma_cache {
struct mtx uc_lock; /* Spin lock on this cpu's bucket */
int uc_count; /* Highest value ub_ptr can have */
uma_bucket_t uc_freebucket; /* Bucket we're freeing to */
uma_bucket_t uc_allocbucket; /* Bucket to allocate from */
u_int64_t uc_allocs; /* Count of allocations */
};
typedef struct uma_cache * uma_cache_t;
#define LOCKNAME_LEN 16 /* Length of the name for cpu locks */
/*
* Zone management structure
*
* TODO: Optimize for cache line size
*
*/
struct uma_zone {
char uz_lname[LOCKNAME_LEN]; /* Text name for the cpu lock */
char *uz_name; /* Text name of the zone */
LIST_ENTRY(uma_zone) uz_link; /* List of all zones */
u_int32_t uz_align; /* Alignment mask */
u_int32_t uz_pages; /* Total page count */
/* Used during alloc / free */
struct mtx uz_lock; /* Lock for the zone */
u_int32_t uz_free; /* Count of items free in slabs */
u_int16_t uz_ipers; /* Items per slab */
u_int16_t uz_flags; /* Internal flags */
LIST_HEAD(,uma_slab) uz_part_slab; /* partially allocated slabs */
LIST_HEAD(,uma_slab) uz_free_slab; /* empty slab list */
LIST_HEAD(,uma_slab) uz_full_slab; /* full slabs */
LIST_HEAD(,uma_bucket) uz_full_bucket; /* full buckets */
LIST_HEAD(,uma_bucket) uz_free_bucket; /* Buckets for frees */
u_int32_t uz_size; /* Requested size of each item */
u_int32_t uz_rsize; /* Real size of each item */
struct uma_hash uz_hash;
u_int16_t uz_pgoff; /* Offset to uma_slab struct */
u_int16_t uz_ppera; /* pages per allocation from backend */
u_int16_t uz_cacheoff; /* Next cache offset */
u_int16_t uz_cachemax; /* Max cache offset */
uma_ctor uz_ctor; /* Constructor for each allocation */
uma_dtor uz_dtor; /* Destructor */
u_int64_t uz_allocs; /* Total number of allocations */
uma_init uz_init; /* Initializer for each item */
uma_fini uz_fini; /* Discards memory */
uma_alloc uz_allocf; /* Allocation function */
uma_free uz_freef; /* Free routine */
struct vm_object *uz_obj; /* Zone specific object */
vm_offset_t uz_kva; /* Base kva for zones with objs */
u_int32_t uz_maxpages; /* Maximum number of pages to alloc */
u_int32_t uz_cachefree; /* Last count of items free in caches */
u_int64_t uz_oallocs; /* old allocs count */
u_int64_t uz_wssize; /* Working set size */
int uz_recurse; /* Allocation recursion count */
/*
* This HAS to be the last item because we adjust the zone size
* based on NCPU and then allocate the space for the zones.
*/
struct uma_cache uz_cpu[1]; /* Per cpu caches */
};
#define UMA_CACHE_INC 16 /* How much will we move data */
#define UMA_ZFLAG_OFFPAGE 0x0001 /* Struct slab/freelist off page */
#define UMA_ZFLAG_PRIVALLOC 0x0002 /* Zone has supplied it's own alloc */
#define UMA_ZFLAG_INTERNAL 0x0004 /* Internal zone, no offpage no PCPU */
#define UMA_ZFLAG_MALLOC 0x0008 /* Zone created by malloc */
#define UMA_ZFLAG_NOFREE 0x0010 /* Don't free data from this zone */
/* This lives in uflags */
#define UMA_ZONE_INTERNAL 0x1000 /* Internal zone for uflags */
/* Internal prototypes */
static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data);
void *uma_large_malloc(int size, int wait);
void uma_large_free(uma_slab_t slab);
/* Lock Macros */
#define ZONE_LOCK_INIT(z) mtx_init(&(z)->uz_lock, (z)->uz_name, MTX_DEF)
#define ZONE_LOCK_FINI(z) mtx_destroy(&(z)->uz_lock)
#define ZONE_LOCK(z) mtx_lock(&(z)->uz_lock)
#define ZONE_UNLOCK(z) mtx_unlock(&(z)->uz_lock)
#define CPU_LOCK_INIT(z, cpu) \
mtx_init(&(z)->uz_cpu[(cpu)].uc_lock, (z)->uz_lname, MTX_DEF)
#define CPU_LOCK_FINI(z, cpu) \
mtx_destroy(&(z)->uz_cpu[(cpu)].uc_lock)
#define CPU_LOCK(z, cpu) \
mtx_lock(&(z)->uz_cpu[(cpu)].uc_lock)
#define CPU_UNLOCK(z, cpu) \
mtx_unlock(&(z)->uz_cpu[(cpu)].uc_lock)
/*
* Find a slab within a hash table. This is used for OFFPAGE zones to lookup
* the slab structure.
*
* Arguments:
* hash The hash table to search.
* data The base page of the item.
*
* Returns:
* A pointer to a slab if successful, else NULL.
*/
static __inline uma_slab_t
hash_sfind(struct uma_hash *hash, u_int8_t *data)
{
uma_slab_t slab;
int hval;
hval = UMA_HASH(hash, data);
SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
if ((u_int8_t *)slab->us_data == data)
return (slab);
}
return (NULL);
}
#endif /* VM_UMA_INT_H */