1 /*- 2 * Copyright (c) 2002, 2003, 2004, 2005 Jeffrey Roberson <jeff@FreeBSD.org> 3 * Copyright (c) 2004, 2005 Bosko Milekic <bmilekic@FreeBSD.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice unmodified, this list of conditions, and the following 11 * disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * $FreeBSD$ 28 * 29 */ 30 31 /* 32 * This file includes definitions, structures, prototypes, and inlines that 33 * should not be used outside of the actual implementation of UMA. 34 */ 35 36 /* 37 * Here's a quick description of the relationship between the objects: 38 * 39 * Kegs contain lists of slabs which are stored in either the full bin, empty 40 * bin, or partially allocated bin, to reduce fragmentation. They also contain 41 * the user supplied value for size, which is adjusted for alignment purposes 42 * and rsize is the result of that. The Keg also stores information for 43 * managing a hash of page addresses that maps pages to uma_slab_t structures 44 * for pages that don't have embedded uma_slab_t's. 45 * 46 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may 47 * be allocated off the page from a special slab zone. The free list within a 48 * slab is managed with a linked list of indexes, which are 8 bit values. If 49 * UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit 50 * values. Currently on alpha you can get 250 or so 32 byte items and on x86 51 * you can get 250 or so 16byte items. For item sizes that would yield more 52 * than 10% memory waste we potentially allocate a separate uma_slab_t if this 53 * will improve the number of items per slab that will fit. 54 * 55 * Other potential space optimizations are storing the 8bit of linkage in space 56 * wasted between items due to alignment problems. This may yield a much better 57 * memory footprint for certain sizes of objects. Another alternative is to 58 * increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer 59 * dynamic slab sizes because we could stick with 8 bit indexes and only use 60 * large slab sizes for zones with a lot of waste per slab. This may create 61 * ineffeciencies in the vm subsystem due to fragmentation in the address space. 62 * 63 * The only really gross cases, with regards to memory waste, are for those 64 * items that are just over half the page size. You can get nearly 50% waste, 65 * so you fall back to the memory footprint of the power of two allocator. I 66 * have looked at memory allocation sizes on many of the machines available to 67 * me, and there does not seem to be an abundance of allocations at this range 68 * so at this time it may not make sense to optimize for it. This can, of 69 * course, be solved with dynamic slab sizes. 70 * 71 * Kegs may serve multiple Zones but by far most of the time they only serve 72 * one. When a Zone is created, a Keg is allocated and setup for it. While 73 * the backing Keg stores slabs, the Zone caches Buckets of items allocated 74 * from the slabs. Each Zone is equipped with an init/fini and ctor/dtor 75 * pair, as well as with its own set of small per-CPU caches, layered above 76 * the Zone's general Bucket cache. 77 * 78 * The PCPU caches are protected by critical sections, and may be accessed 79 * safely only from their associated CPU, while the Zones backed by the same 80 * Keg all share a common Keg lock (to coalesce contention on the backing 81 * slabs). The backing Keg typically only serves one Zone but in the case of 82 * multiple Zones, one of the Zones is considered the Master Zone and all 83 * Zone-related stats from the Keg are done in the Master Zone. For an 84 * example of a Multi-Zone setup, refer to the Mbuf allocation code. 85 */ 86 87 /* 88 * This is the representation for normal (Non OFFPAGE slab) 89 * 90 * i == item 91 * s == slab pointer 92 * 93 * <---------------- Page (UMA_SLAB_SIZE) ------------------> 94 * ___________________________________________________________ 95 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ | 96 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header|| 97 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________|| 98 * |___________________________________________________________| 99 * 100 * 101 * This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE. 102 * 103 * ___________________________________________________________ 104 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ | 105 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| | 106 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| | 107 * |___________________________________________________________| 108 * ___________ ^ 109 * |slab header| | 110 * |___________|---* 111 * 112 */ 113 114 #ifndef VM_UMA_INT_H 115 #define VM_UMA_INT_H 116 117 #define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */ 118 #define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */ 119 #define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */ 120 121 #define UMA_BOOT_PAGES 48 /* Pages allocated for startup */ 122 123 /* Max waste before going to off page slab management */ 124 #define UMA_MAX_WASTE (UMA_SLAB_SIZE / 10) 125 126 /* 127 * I doubt there will be many cases where this is exceeded. This is the initial 128 * size of the hash table for uma_slabs that are managed off page. This hash 129 * does expand by powers of two. Currently it doesn't get smaller. 130 */ 131 #define UMA_HASH_SIZE_INIT 32 132 133 /* 134 * I should investigate other hashing algorithms. This should yield a low 135 * number of collisions if the pages are relatively contiguous. 136 * 137 * This is the same algorithm that most processor caches use. 138 * 139 * I'm shifting and masking instead of % because it should be faster. 140 */ 141 142 #define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) & \ 143 (h)->uh_hashmask) 144 145 #define UMA_HASH_INSERT(h, s, mem) \ 146 SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \ 147 (mem))], (s), us_hlink); 148 #define UMA_HASH_REMOVE(h, s, mem) \ 149 SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \ 150 (mem))], (s), uma_slab, us_hlink); 151 152 /* Hash table for freed address -> slab translation */ 153 154 SLIST_HEAD(slabhead, uma_slab); 155 156 struct uma_hash { 157 struct slabhead *uh_slab_hash; /* Hash table for slabs */ 158 int uh_hashsize; /* Current size of the hash table */ 159 int uh_hashmask; /* Mask used during hashing */ 160 }; 161 162 /* 163 * Structures for per cpu queues. 164 */ 165 166 struct uma_bucket { 167 LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */ 168 int16_t ub_cnt; /* Count of free items. */ 169 int16_t ub_entries; /* Max items. */ 170 void *ub_bucket[]; /* actual allocation storage */ 171 }; 172 173 typedef struct uma_bucket * uma_bucket_t; 174 175 struct uma_cache { 176 uma_bucket_t uc_freebucket; /* Bucket we're freeing to */ 177 uma_bucket_t uc_allocbucket; /* Bucket to allocate from */ 178 u_int64_t uc_allocs; /* Count of allocations */ 179 u_int64_t uc_frees; /* Count of frees */ 180 }; 181 182 typedef struct uma_cache * uma_cache_t; 183 184 /* 185 * Keg management structure 186 * 187 * TODO: Optimize for cache line size 188 * 189 */ 190 struct uma_keg { 191 LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */ 192 193 struct mtx uk_lock; /* Lock for the keg */ 194 struct uma_hash uk_hash; 195 196 LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */ 197 LIST_HEAD(,uma_slab) uk_part_slab; /* partially allocated slabs */ 198 LIST_HEAD(,uma_slab) uk_free_slab; /* empty slab list */ 199 LIST_HEAD(,uma_slab) uk_full_slab; /* full slabs */ 200 201 u_int32_t uk_recurse; /* Allocation recursion count */ 202 u_int32_t uk_align; /* Alignment mask */ 203 u_int32_t uk_pages; /* Total page count */ 204 u_int32_t uk_free; /* Count of items free in slabs */ 205 u_int32_t uk_size; /* Requested size of each item */ 206 u_int32_t uk_rsize; /* Real size of each item */ 207 u_int32_t uk_maxpages; /* Maximum number of pages to alloc */ 208 209 uma_init uk_init; /* Keg's init routine */ 210 uma_fini uk_fini; /* Keg's fini routine */ 211 uma_alloc uk_allocf; /* Allocation function */ 212 uma_free uk_freef; /* Free routine */ 213 214 struct vm_object *uk_obj; /* Zone specific object */ 215 vm_offset_t uk_kva; /* Base kva for zones with objs */ 216 uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */ 217 218 u_int16_t uk_pgoff; /* Offset to uma_slab struct */ 219 u_int16_t uk_ppera; /* pages per allocation from backend */ 220 u_int16_t uk_ipers; /* Items per slab */ 221 u_int32_t uk_flags; /* Internal flags */ 222 }; 223 224 /* Simpler reference to uma_keg for internal use. */ 225 typedef struct uma_keg * uma_keg_t; 226 227 /* Page management structure */ 228 229 /* Sorry for the union, but space efficiency is important */ 230 struct uma_slab_head { 231 uma_keg_t us_keg; /* Keg we live in */ 232 union { 233 LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */ 234 unsigned long _us_size; /* Size of allocation */ 235 } us_type; 236 SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */ 237 u_int8_t *us_data; /* First item */ 238 u_int8_t us_flags; /* Page flags see uma.h */ 239 u_int8_t us_freecount; /* How many are free? */ 240 u_int8_t us_firstfree; /* First free item index */ 241 }; 242 243 /* The standard slab structure */ 244 struct uma_slab { 245 struct uma_slab_head us_head; /* slab header data */ 246 struct { 247 u_int8_t us_item; 248 } us_freelist[1]; /* actual number bigger */ 249 }; 250 251 /* 252 * The slab structure for UMA_ZONE_REFCNT zones for whose items we 253 * maintain reference counters in the slab for. 254 */ 255 struct uma_slab_refcnt { 256 struct uma_slab_head us_head; /* slab header data */ 257 struct { 258 u_int8_t us_item; 259 u_int32_t us_refcnt; 260 } us_freelist[1]; /* actual number bigger */ 261 }; 262 263 #define us_keg us_head.us_keg 264 #define us_link us_head.us_type._us_link 265 #define us_size us_head.us_type._us_size 266 #define us_hlink us_head.us_hlink 267 #define us_data us_head.us_data 268 #define us_flags us_head.us_flags 269 #define us_freecount us_head.us_freecount 270 #define us_firstfree us_head.us_firstfree 271 272 typedef struct uma_slab * uma_slab_t; 273 typedef struct uma_slab_refcnt * uma_slabrefcnt_t; 274 275 /* 276 * These give us the size of one free item reference within our corresponding 277 * uma_slab structures, so that our calculations during zone setup are correct 278 * regardless of what the compiler decides to do with padding the structure 279 * arrays within uma_slab. 280 */ 281 #define UMA_FRITM_SZ (sizeof(struct uma_slab) - sizeof(struct uma_slab_head)) 282 #define UMA_FRITMREF_SZ (sizeof(struct uma_slab_refcnt) - \ 283 sizeof(struct uma_slab_head)) 284 285 /* 286 * Zone management structure 287 * 288 * TODO: Optimize for cache line size 289 * 290 */ 291 struct uma_zone { 292 char *uz_name; /* Text name of the zone */ 293 struct mtx *uz_lock; /* Lock for the zone (keg's lock) */ 294 uma_keg_t uz_keg; /* Our underlying Keg */ 295 296 LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */ 297 LIST_HEAD(,uma_bucket) uz_full_bucket; /* full buckets */ 298 LIST_HEAD(,uma_bucket) uz_free_bucket; /* Buckets for frees */ 299 300 uma_ctor uz_ctor; /* Constructor for each allocation */ 301 uma_dtor uz_dtor; /* Destructor */ 302 uma_init uz_init; /* Initializer for each item */ 303 uma_fini uz_fini; /* Discards memory */ 304 305 u_int64_t uz_allocs; /* Total number of allocations */ 306 u_int64_t uz_frees; /* Total number of frees */ 307 u_int64_t uz_fails; /* Total number of alloc failures */ 308 uint16_t uz_fills; /* Outstanding bucket fills */ 309 uint16_t uz_count; /* Highest value ub_ptr can have */ 310 311 /* 312 * This HAS to be the last item because we adjust the zone size 313 * based on NCPU and then allocate the space for the zones. 314 */ 315 struct uma_cache uz_cpu[1]; /* Per cpu caches */ 316 }; 317 318 /* 319 * These flags must not overlap with the UMA_ZONE flags specified in uma.h. 320 */ 321 #define UMA_ZFLAG_PRIVALLOC 0x10000000 /* Use uz_allocf. */ 322 #define UMA_ZFLAG_INTERNAL 0x20000000 /* No offpage no PCPU. */ 323 #define UMA_ZFLAG_FULL 0x40000000 /* Reached uz_maxpages */ 324 #define UMA_ZFLAG_CACHEONLY 0x80000000 /* Don't ask VM for buckets. */ 325 326 #ifdef _KERNEL 327 /* Internal prototypes */ 328 static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data); 329 void *uma_large_malloc(int size, int wait); 330 void uma_large_free(uma_slab_t slab); 331 332 /* Lock Macros */ 333 334 #define ZONE_LOCK_INIT(z, lc) \ 335 do { \ 336 if ((lc)) \ 337 mtx_init((z)->uz_lock, (z)->uz_name, \ 338 (z)->uz_name, MTX_DEF | MTX_DUPOK); \ 339 else \ 340 mtx_init((z)->uz_lock, (z)->uz_name, \ 341 "UMA zone", MTX_DEF | MTX_DUPOK); \ 342 } while (0) 343 344 #define ZONE_LOCK_FINI(z) mtx_destroy((z)->uz_lock) 345 #define ZONE_LOCK(z) mtx_lock((z)->uz_lock) 346 #define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lock) 347 348 /* 349 * Find a slab within a hash table. This is used for OFFPAGE zones to lookup 350 * the slab structure. 351 * 352 * Arguments: 353 * hash The hash table to search. 354 * data The base page of the item. 355 * 356 * Returns: 357 * A pointer to a slab if successful, else NULL. 358 */ 359 static __inline uma_slab_t 360 hash_sfind(struct uma_hash *hash, u_int8_t *data) 361 { 362 uma_slab_t slab; 363 int hval; 364 365 hval = UMA_HASH(hash, data); 366 367 SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) { 368 if ((u_int8_t *)slab->us_data == data) 369 return (slab); 370 } 371 return (NULL); 372 } 373 374 static __inline uma_slab_t 375 vtoslab(vm_offset_t va) 376 { 377 vm_page_t p; 378 uma_slab_t slab; 379 380 p = PHYS_TO_VM_PAGE(pmap_kextract(va)); 381 slab = (uma_slab_t )p->object; 382 383 if (p->flags & PG_SLAB) 384 return (slab); 385 else 386 return (NULL); 387 } 388 389 static __inline void 390 vsetslab(vm_offset_t va, uma_slab_t slab) 391 { 392 vm_page_t p; 393 394 p = PHYS_TO_VM_PAGE(pmap_kextract(va)); 395 p->object = (vm_object_t)slab; 396 p->flags |= PG_SLAB; 397 } 398 399 static __inline void 400 vsetobj(vm_offset_t va, vm_object_t obj) 401 { 402 vm_page_t p; 403 404 p = PHYS_TO_VM_PAGE(pmap_kextract(va)); 405 p->object = obj; 406 p->flags &= ~PG_SLAB; 407 } 408 409 /* 410 * The following two functions may be defined by architecture specific code 411 * if they can provide more effecient allocation functions. This is useful 412 * for using direct mapped addresses. 413 */ 414 void *uma_small_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait); 415 void uma_small_free(void *mem, int size, u_int8_t flags); 416 #endif /* _KERNEL */ 417 418 #endif /* VM_UMA_INT_H */ 419