1 /* 2 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 * 28 */ 29 30 /* 31 * This file includes definitions, structures, prototypes, and inlines that 32 * should not be used outside of the actual implementation of UMA. 33 */ 34 35 /* 36 * Here's a quick description of the relationship between the objects: 37 * 38 * Kegs contain lists of slabs which are stored in either the full bin, empty 39 * bin, or partially allocated bin, to reduce fragmentation. They also contain 40 * the user supplied value for size, which is adjusted for alignment purposes 41 * and rsize is the result of that. The Keg also stores information for 42 * managing a hash of page addresses that maps pages to uma_slab_t structures 43 * for pages that don't have embedded uma_slab_t's. 44 * 45 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may 46 * be allocated off the page from a special slab zone. The free list within a 47 * slab is managed with a linked list of indexes, which are 8 bit values. If 48 * UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit 49 * values. Currently on alpha you can get 250 or so 32 byte items and on x86 50 * you can get 250 or so 16byte items. For item sizes that would yield more 51 * than 10% memory waste we potentially allocate a separate uma_slab_t if this 52 * will improve the number of items per slab that will fit. 53 * 54 * Other potential space optimizations are storing the 8bit of linkage in space 55 * wasted between items due to alignment problems. This may yield a much better 56 * memory footprint for certain sizes of objects. Another alternative is to 57 * increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer 58 * dynamic slab sizes because we could stick with 8 bit indexes and only use 59 * large slab sizes for zones with a lot of waste per slab. This may create 60 * ineffeciencies in the vm subsystem due to fragmentation in the address space. 61 * 62 * The only really gross cases, with regards to memory waste, are for those 63 * items that are just over half the page size. You can get nearly 50% waste, 64 * so you fall back to the memory footprint of the power of two allocator. I 65 * have looked at memory allocation sizes on many of the machines available to 66 * me, and there does not seem to be an abundance of allocations at this range 67 * so at this time it may not make sense to optimize for it. This can, of 68 * course, be solved with dynamic slab sizes. 69 * 70 * Kegs may serve multiple Zones but by far most of the time they only serve 71 * one. When a Zone is created, a Keg is allocated and setup for it. While 72 * the backing Keg stores slabs, the Zone caches Buckets of items allocated 73 * from the slabs. Each Zone is equipped with an init/fini and ctor/dtor 74 * pair, as well as with its own set of small per-CPU caches, layered above 75 * the Zone's general Bucket cache. 76 * 77 * The PCPU caches are protected by their own locks, while the Zones backed 78 * by the same Keg all share a common Keg lock (to coalesce contention on 79 * the backing slabs). The backing Keg typically only serves one Zone but 80 * in the case of multiple Zones, one of the Zones is considered the 81 * Master Zone and all Zone-related stats from the Keg are done in the 82 * Master Zone. For an example of a Multi-Zone setup, refer to the 83 * Mbuf allocation code. 84 */ 85 86 /* 87 * This is the representation for normal (Non OFFPAGE slab) 88 * 89 * i == item 90 * s == slab pointer 91 * 92 * <---------------- Page (UMA_SLAB_SIZE) ------------------> 93 * ___________________________________________________________ 94 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ | 95 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header|| 96 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________|| 97 * |___________________________________________________________| 98 * 99 * 100 * This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE. 101 * 102 * ___________________________________________________________ 103 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ | 104 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| | 105 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| | 106 * |___________________________________________________________| 107 * ___________ ^ 108 * |slab header| | 109 * |___________|---* 110 * 111 */ 112 113 #ifndef VM_UMA_INT_H 114 #define VM_UMA_INT_H 115 116 #define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */ 117 #define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */ 118 #define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */ 119 120 #define UMA_BOOT_PAGES 40 /* Pages allocated for startup */ 121 122 /* Max waste before going to off page slab management */ 123 #define UMA_MAX_WASTE (UMA_SLAB_SIZE / 10) 124 125 /* 126 * I doubt there will be many cases where this is exceeded. This is the initial 127 * size of the hash table for uma_slabs that are managed off page. This hash 128 * does expand by powers of two. Currently it doesn't get smaller. 129 */ 130 #define UMA_HASH_SIZE_INIT 32 131 132 /* 133 * I should investigate other hashing algorithms. This should yield a low 134 * number of collisions if the pages are relatively contiguous. 135 * 136 * This is the same algorithm that most processor caches use. 137 * 138 * I'm shifting and masking instead of % because it should be faster. 139 */ 140 141 #define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) & \ 142 (h)->uh_hashmask) 143 144 #define UMA_HASH_INSERT(h, s, mem) \ 145 SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \ 146 (mem))], (s), us_hlink); 147 #define UMA_HASH_REMOVE(h, s, mem) \ 148 SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \ 149 (mem))], (s), uma_slab, us_hlink); 150 151 /* Hash table for freed address -> slab translation */ 152 153 SLIST_HEAD(slabhead, uma_slab); 154 155 struct uma_hash { 156 struct slabhead *uh_slab_hash; /* Hash table for slabs */ 157 int uh_hashsize; /* Current size of the hash table */ 158 int uh_hashmask; /* Mask used during hashing */ 159 }; 160 161 /* 162 * Structures for per cpu queues. 163 */ 164 165 struct uma_bucket { 166 LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */ 167 int16_t ub_cnt; /* Count of free items. */ 168 int16_t ub_entries; /* Max items. */ 169 void *ub_bucket[]; /* actual allocation storage */ 170 }; 171 172 typedef struct uma_bucket * uma_bucket_t; 173 174 struct uma_cache { 175 uma_bucket_t uc_freebucket; /* Bucket we're freeing to */ 176 uma_bucket_t uc_allocbucket; /* Bucket to allocate from */ 177 u_int64_t uc_allocs; /* Count of allocations */ 178 }; 179 180 typedef struct uma_cache * uma_cache_t; 181 182 /* 183 * Keg management structure 184 * 185 * TODO: Optimize for cache line size 186 * 187 */ 188 struct uma_keg { 189 LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */ 190 191 struct mtx uk_lock; /* Lock for the keg */ 192 struct uma_hash uk_hash; 193 194 LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */ 195 LIST_HEAD(,uma_slab) uk_part_slab; /* partially allocated slabs */ 196 LIST_HEAD(,uma_slab) uk_free_slab; /* empty slab list */ 197 LIST_HEAD(,uma_slab) uk_full_slab; /* full slabs */ 198 199 u_int32_t uk_recurse; /* Allocation recursion count */ 200 u_int32_t uk_align; /* Alignment mask */ 201 u_int32_t uk_pages; /* Total page count */ 202 u_int32_t uk_free; /* Count of items free in slabs */ 203 u_int32_t uk_size; /* Requested size of each item */ 204 u_int32_t uk_rsize; /* Real size of each item */ 205 u_int32_t uk_maxpages; /* Maximum number of pages to alloc */ 206 207 uma_init uk_init; /* Keg's init routine */ 208 uma_fini uk_fini; /* Keg's fini routine */ 209 uma_alloc uk_allocf; /* Allocation function */ 210 uma_free uk_freef; /* Free routine */ 211 212 struct vm_object *uk_obj; /* Zone specific object */ 213 vm_offset_t uk_kva; /* Base kva for zones with objs */ 214 uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */ 215 216 u_int16_t uk_pgoff; /* Offset to uma_slab struct */ 217 u_int16_t uk_ppera; /* pages per allocation from backend */ 218 u_int16_t uk_ipers; /* Items per slab */ 219 u_int16_t uk_flags; /* Internal flags */ 220 }; 221 222 /* Simpler reference to uma_keg for internal use. */ 223 typedef struct uma_keg * uma_keg_t; 224 225 /* Page management structure */ 226 227 /* Sorry for the union, but space efficiency is important */ 228 struct uma_slab_head { 229 uma_keg_t us_keg; /* Keg we live in */ 230 union { 231 LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */ 232 unsigned long _us_size; /* Size of allocation */ 233 } us_type; 234 SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */ 235 u_int8_t *us_data; /* First item */ 236 u_int8_t us_flags; /* Page flags see uma.h */ 237 u_int8_t us_freecount; /* How many are free? */ 238 u_int8_t us_firstfree; /* First free item index */ 239 }; 240 241 /* The standard slab structure */ 242 struct uma_slab { 243 struct uma_slab_head us_head; /* slab header data */ 244 struct { 245 u_int8_t us_item; 246 } us_freelist[1]; /* actual number bigger */ 247 }; 248 249 /* 250 * The slab structure for UMA_ZONE_REFCNT zones for whose items we 251 * maintain reference counters in the slab for. 252 */ 253 struct uma_slab_refcnt { 254 struct uma_slab_head us_head; /* slab header data */ 255 struct { 256 u_int8_t us_item; 257 u_int32_t us_refcnt; 258 } us_freelist[1]; /* actual number bigger */ 259 }; 260 261 #define us_keg us_head.us_keg 262 #define us_link us_head.us_type._us_link 263 #define us_size us_head.us_type._us_size 264 #define us_hlink us_head.us_hlink 265 #define us_data us_head.us_data 266 #define us_flags us_head.us_flags 267 #define us_freecount us_head.us_freecount 268 #define us_firstfree us_head.us_firstfree 269 270 typedef struct uma_slab * uma_slab_t; 271 typedef struct uma_slab_refcnt * uma_slabrefcnt_t; 272 273 /* 274 * These give us the size of one free item reference within our corresponding 275 * uma_slab structures, so that our calculations during zone setup are correct 276 * regardless of what the compiler decides to do with padding the structure 277 * arrays within uma_slab. 278 */ 279 #define UMA_FRITM_SZ (sizeof(struct uma_slab) - sizeof(struct uma_slab_head)) 280 #define UMA_FRITMREF_SZ (sizeof(struct uma_slab_refcnt) - \ 281 sizeof(struct uma_slab_head)) 282 283 /* 284 * Zone management structure 285 * 286 * TODO: Optimize for cache line size 287 * 288 */ 289 struct uma_zone { 290 char *uz_name; /* Text name of the zone */ 291 struct mtx *uz_lock; /* Lock for the zone (keg's lock) */ 292 uma_keg_t uz_keg; /* Our underlying Keg */ 293 294 LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */ 295 LIST_HEAD(,uma_bucket) uz_full_bucket; /* full buckets */ 296 LIST_HEAD(,uma_bucket) uz_free_bucket; /* Buckets for frees */ 297 298 uma_ctor uz_ctor; /* Constructor for each allocation */ 299 uma_dtor uz_dtor; /* Destructor */ 300 uma_init uz_init; /* Initializer for each item */ 301 uma_fini uz_fini; /* Discards memory */ 302 303 u_int64_t uz_allocs; /* Total number of allocations */ 304 uint16_t uz_fills; /* Outstanding bucket fills */ 305 uint16_t uz_count; /* Highest value ub_ptr can have */ 306 307 /* 308 * This HAS to be the last item because we adjust the zone size 309 * based on NCPU and then allocate the space for the zones. 310 */ 311 struct uma_cache uz_cpu[1]; /* Per cpu caches */ 312 }; 313 314 /* 315 * These flags must not overlap with the UMA_ZONE flags specified in uma.h. 316 */ 317 #define UMA_ZFLAG_PRIVALLOC 0x1000 /* Use uz_allocf. */ 318 #define UMA_ZFLAG_INTERNAL 0x2000 /* No offpage no PCPU. */ 319 #define UMA_ZFLAG_FULL 0x4000 /* Reached uz_maxpages */ 320 #define UMA_ZFLAG_CACHEONLY 0x8000 /* Don't ask VM for buckets. */ 321 322 /* Internal prototypes */ 323 static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data); 324 void *uma_large_malloc(int size, int wait); 325 void uma_large_free(uma_slab_t slab); 326 327 /* Lock Macros */ 328 329 #define ZONE_LOCK_INIT(z, lc) \ 330 do { \ 331 if ((lc)) \ 332 mtx_init((z)->uz_lock, (z)->uz_name, \ 333 (z)->uz_name, MTX_DEF | MTX_DUPOK); \ 334 else \ 335 mtx_init((z)->uz_lock, (z)->uz_name, \ 336 "UMA zone", MTX_DEF | MTX_DUPOK); \ 337 } while (0) 338 339 #define ZONE_LOCK_FINI(z) mtx_destroy((z)->uz_lock) 340 #define ZONE_LOCK(z) mtx_lock((z)->uz_lock) 341 #define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lock) 342 343 #define CPU_LOCK_INIT(cpu) \ 344 mtx_init(&uma_pcpu_mtx[(cpu)], "UMA pcpu", "UMA pcpu", \ 345 MTX_DEF | MTX_DUPOK) 346 347 #define CPU_LOCK(cpu) \ 348 mtx_lock(&uma_pcpu_mtx[(cpu)]) 349 350 #define CPU_UNLOCK(cpu) \ 351 mtx_unlock(&uma_pcpu_mtx[(cpu)]) 352 353 /* 354 * Find a slab within a hash table. This is used for OFFPAGE zones to lookup 355 * the slab structure. 356 * 357 * Arguments: 358 * hash The hash table to search. 359 * data The base page of the item. 360 * 361 * Returns: 362 * A pointer to a slab if successful, else NULL. 363 */ 364 static __inline uma_slab_t 365 hash_sfind(struct uma_hash *hash, u_int8_t *data) 366 { 367 uma_slab_t slab; 368 int hval; 369 370 hval = UMA_HASH(hash, data); 371 372 SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) { 373 if ((u_int8_t *)slab->us_data == data) 374 return (slab); 375 } 376 return (NULL); 377 } 378 379 static __inline uma_slab_t 380 vtoslab(vm_offset_t va) 381 { 382 vm_page_t p; 383 uma_slab_t slab; 384 385 p = PHYS_TO_VM_PAGE(pmap_kextract(va)); 386 slab = (uma_slab_t )p->object; 387 388 if (p->flags & PG_SLAB) 389 return (slab); 390 else 391 return (NULL); 392 } 393 394 static __inline void 395 vsetslab(vm_offset_t va, uma_slab_t slab) 396 { 397 vm_page_t p; 398 399 p = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)va)); 400 p->object = (vm_object_t)slab; 401 p->flags |= PG_SLAB; 402 } 403 404 static __inline void 405 vsetobj(vm_offset_t va, vm_object_t obj) 406 { 407 vm_page_t p; 408 409 p = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)va)); 410 p->object = obj; 411 p->flags &= ~PG_SLAB; 412 } 413 414 /* 415 * The following two functions may be defined by architecture specific code 416 * if they can provide more effecient allocation functions. This is useful 417 * for using direct mapped addresses. 418 */ 419 void *uma_small_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait); 420 void uma_small_free(void *mem, int size, u_int8_t flags); 421 422 #endif /* VM_UMA_INT_H */ 423