2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2002-2005, 2009, 2013 Jeffrey Roberson <jeff@FreeBSD.org>
5 * Copyright (c) 2004, 2005 Bosko Milekic <bmilekic@FreeBSD.org>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice unmodified, this list of conditions, and the following
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
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33 #include <sys/_bitset.h>
34 #include <sys/_task.h>
37 * This file includes definitions, structures, prototypes, and inlines that
38 * should not be used outside of the actual implementation of UMA.
42 * The brief summary; Zones describe unique allocation types. Zones are
43 * organized into per-CPU caches which are filled by buckets. Buckets are
44 * organized according to memory domains. Buckets are filled from kegs which
45 * are also organized according to memory domains. Kegs describe a unique
46 * allocation type, backend memory provider, and layout. Kegs are associated
47 * with one or more zones and zones reference one or more kegs. Kegs provide
48 * slabs which are virtually contiguous collections of pages. Each slab is
49 * broken down int one or more items that will satisfy an individual allocation.
51 * Allocation is satisfied in the following order:
53 * 2) Per-domain cache of buckets
54 * 3) Slab from any of N kegs
55 * 4) Backend page provider
57 * More detail on individual objects is contained below:
59 * Kegs contain lists of slabs which are stored in either the full bin, empty
60 * bin, or partially allocated bin, to reduce fragmentation. They also contain
61 * the user supplied value for size, which is adjusted for alignment purposes
62 * and rsize is the result of that. The Keg also stores information for
63 * managing a hash of page addresses that maps pages to uma_slab_t structures
64 * for pages that don't have embedded uma_slab_t's.
66 * Keg slab lists are organized by memory domain to support NUMA allocation
67 * policies. By default allocations are spread across domains to reduce the
68 * potential for hotspots. Special keg creation flags may be specified to
69 * prefer location allocation. However there is no strict enforcement as frees
70 * may happen on any CPU and these are returned to the CPU-local cache
71 * regardless of the originating domain.
73 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
74 * be allocated off the page from a special slab zone. The free list within a
75 * slab is managed with a bitmask. For item sizes that would yield more than
76 * 10% memory waste we potentially allocate a separate uma_slab_t if this will
77 * improve the number of items per slab that will fit.
79 * The only really gross cases, with regards to memory waste, are for those
80 * items that are just over half the page size. You can get nearly 50% waste,
81 * so you fall back to the memory footprint of the power of two allocator. I
82 * have looked at memory allocation sizes on many of the machines available to
83 * me, and there does not seem to be an abundance of allocations at this range
84 * so at this time it may not make sense to optimize for it. This can, of
85 * course, be solved with dynamic slab sizes.
87 * Kegs may serve multiple Zones but by far most of the time they only serve
88 * one. When a Zone is created, a Keg is allocated and setup for it. While
89 * the backing Keg stores slabs, the Zone caches Buckets of items allocated
90 * from the slabs. Each Zone is equipped with an init/fini and ctor/dtor
91 * pair, as well as with its own set of small per-CPU caches, layered above
92 * the Zone's general Bucket cache.
94 * The PCPU caches are protected by critical sections, and may be accessed
95 * safely only from their associated CPU, while the Zones backed by the same
96 * Keg all share a common Keg lock (to coalesce contention on the backing
97 * slabs). The backing Keg typically only serves one Zone but in the case of
98 * multiple Zones, one of the Zones is considered the Master Zone and all
99 * Zone-related stats from the Keg are done in the Master Zone. For an
100 * example of a Multi-Zone setup, refer to the Mbuf allocation code.
104 * This is the representation for normal (Non OFFPAGE slab)
109 * <---------------- Page (UMA_SLAB_SIZE) ------------------>
110 * ___________________________________________________________
111 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ |
112 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
113 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________||
114 * |___________________________________________________________|
117 * This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
119 * ___________________________________________________________
120 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
121 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |
122 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |
123 * |___________________________________________________________|
133 #define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */
134 #define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */
135 #define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */
137 #define UMA_BOOT_PAGES 64 /* Pages allocated for startup */
138 #define UMA_BOOT_PAGES_ZONES 32 /* Multiplier for pages to reserve */
139 /* if uma_zone > PAGE_SIZE */
141 /* Max waste percentage before going to off page slab management */
142 #define UMA_MAX_WASTE 10
145 * I doubt there will be many cases where this is exceeded. This is the initial
146 * size of the hash table for uma_slabs that are managed off page. This hash
147 * does expand by powers of two. Currently it doesn't get smaller.
149 #define UMA_HASH_SIZE_INIT 32
152 * I should investigate other hashing algorithms. This should yield a low
153 * number of collisions if the pages are relatively contiguous.
156 #define UMA_HASH(h, s) ((((uintptr_t)s) >> UMA_SLAB_SHIFT) & (h)->uh_hashmask)
158 #define UMA_HASH_INSERT(h, s, mem) \
159 SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \
160 (mem))], (s), us_hlink)
161 #define UMA_HASH_REMOVE(h, s, mem) \
162 SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \
163 (mem))], (s), uma_slab, us_hlink)
165 /* Hash table for freed address -> slab translation */
167 SLIST_HEAD(slabhead, uma_slab);
170 struct slabhead *uh_slab_hash; /* Hash table for slabs */
171 int uh_hashsize; /* Current size of the hash table */
172 int uh_hashmask; /* Mask used during hashing */
176 * align field or structure to cache line
178 #if defined(__amd64__)
179 #define UMA_ALIGN __aligned(CACHE_LINE_SIZE)
185 * Structures for per cpu queues.
189 LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */
190 int16_t ub_cnt; /* Count of free items. */
191 int16_t ub_entries; /* Max items. */
192 void *ub_bucket[]; /* actual allocation storage */
195 typedef struct uma_bucket * uma_bucket_t;
198 uma_bucket_t uc_freebucket; /* Bucket we're freeing to */
199 uma_bucket_t uc_allocbucket; /* Bucket to allocate from */
200 uint64_t uc_allocs; /* Count of allocations */
201 uint64_t uc_frees; /* Count of frees */
204 typedef struct uma_cache * uma_cache_t;
207 * Per-domain memory list. Embedded in the kegs.
210 LIST_HEAD(,uma_slab) ud_part_slab; /* partially allocated slabs */
211 LIST_HEAD(,uma_slab) ud_free_slab; /* empty slab list */
212 LIST_HEAD(,uma_slab) ud_full_slab; /* full slabs */
215 typedef struct uma_domain * uma_domain_t;
218 * Keg management structure
220 * TODO: Optimize for cache line size
224 struct mtx_padalign uk_lock; /* Lock for the keg */
225 struct uma_hash uk_hash;
227 LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */
229 uint32_t uk_cursor; /* Domain alloc cursor. */
230 uint32_t uk_align; /* Alignment mask */
231 uint32_t uk_pages; /* Total page count */
232 uint32_t uk_free; /* Count of items free in slabs */
233 uint32_t uk_reserve; /* Number of reserved items. */
234 uint32_t uk_size; /* Requested size of each item */
235 uint32_t uk_rsize; /* Real size of each item */
236 uint32_t uk_maxpages; /* Maximum number of pages to alloc */
238 uma_init uk_init; /* Keg's init routine */
239 uma_fini uk_fini; /* Keg's fini routine */
240 uma_alloc uk_allocf; /* Allocation function */
241 uma_free uk_freef; /* Free routine */
243 u_long uk_offset; /* Next free offset from base KVA */
244 vm_offset_t uk_kva; /* Zone base KVA */
245 uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */
247 uint32_t uk_pgoff; /* Offset to uma_slab struct */
248 uint16_t uk_ppera; /* pages per allocation from backend */
249 uint16_t uk_ipers; /* Items per slab */
250 uint32_t uk_flags; /* Internal flags */
252 /* Least used fields go to the last cache line. */
253 const char *uk_name; /* Name of creating zone. */
254 LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */
256 /* Must be last, variable sized. */
257 struct uma_domain uk_domain[]; /* Keg's slab lists. */
259 typedef struct uma_keg * uma_keg_t;
262 * Free bits per-slab.
264 #define SLAB_SETSIZE (PAGE_SIZE / UMA_SMALLEST_UNIT)
265 BITSET_DEFINE(slabbits, SLAB_SETSIZE);
268 * The slab structure manages a single contiguous allocation from backing
269 * store and subdivides it into individually allocatable items.
272 uma_keg_t us_keg; /* Keg we live in */
274 LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */
275 unsigned long _us_size; /* Size of allocation */
277 SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */
278 uint8_t *us_data; /* First item */
279 struct slabbits us_free; /* Free bitmask. */
281 struct slabbits us_debugfree; /* Debug bitmask. */
283 uint16_t us_freecount; /* How many are free? */
284 uint8_t us_flags; /* Page flags see uma.h */
285 uint8_t us_domain; /* Backing NUMA domain. */
288 #define us_link us_type._us_link
289 #define us_size us_type._us_size
292 #error "Slab domain type insufficient"
295 typedef struct uma_slab * uma_slab_t;
296 typedef uma_slab_t (*uma_slaballoc)(uma_zone_t, uma_keg_t, int, int);
299 LIST_ENTRY(uma_klink) kl_link;
302 typedef struct uma_klink *uma_klink_t;
304 struct uma_zone_domain {
305 LIST_HEAD(,uma_bucket) uzd_buckets; /* full buckets */
308 typedef struct uma_zone_domain * uma_zone_domain_t;
311 * Zone management structure
313 * TODO: Optimize for cache line size
317 struct mtx_padalign uz_lock; /* Lock for the zone */
318 struct mtx_padalign *uz_lockptr;
319 const char *uz_name; /* Text name of the zone */
321 LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */
322 struct uma_zone_domain *uz_domain; /* per-domain buckets */
324 LIST_HEAD(,uma_klink) uz_kegs; /* List of kegs. */
325 struct uma_klink uz_klink; /* klink for first keg. */
327 uma_slaballoc uz_slab; /* Allocate a slab from the backend. */
328 uma_ctor uz_ctor; /* Constructor for each allocation */
329 uma_dtor uz_dtor; /* Destructor */
330 uma_init uz_init; /* Initializer for each item */
331 uma_fini uz_fini; /* Finalizer for each item. */
332 uma_import uz_import; /* Import new memory to cache. */
333 uma_release uz_release; /* Release memory from cache. */
334 void *uz_arg; /* Import/release argument. */
336 uint32_t uz_flags; /* Flags inherited from kegs */
337 uint32_t uz_size; /* Size inherited from kegs */
339 volatile u_long uz_allocs UMA_ALIGN; /* Total number of allocations */
340 volatile u_long uz_fails; /* Total number of alloc failures */
341 volatile u_long uz_frees; /* Total number of frees */
342 uint64_t uz_sleeps; /* Total number of alloc sleeps */
343 uint16_t uz_count; /* Amount of items in full bucket */
344 uint16_t uz_count_min; /* Minimal amount of items there */
346 /* The next two fields are used to print a rate-limited warnings. */
347 const char *uz_warning; /* Warning to print on failure */
348 struct timeval uz_ratecheck; /* Warnings rate-limiting */
350 struct task uz_maxaction; /* Task to run when at limit */
353 * This HAS to be the last item because we adjust the zone size
354 * based on NCPU and then allocate the space for the zones.
356 struct uma_cache uz_cpu[]; /* Per cpu caches */
358 /* uz_domain follows here. */
362 * These flags must not overlap with the UMA_ZONE flags specified in uma.h.
364 #define UMA_ZFLAG_MULTI 0x04000000 /* Multiple kegs in the zone. */
365 #define UMA_ZFLAG_DRAINING 0x08000000 /* Running zone_drain. */
366 #define UMA_ZFLAG_BUCKET 0x10000000 /* Bucket zone. */
367 #define UMA_ZFLAG_INTERNAL 0x20000000 /* No offpage no PCPU. */
368 #define UMA_ZFLAG_FULL 0x40000000 /* Reached uz_maxpages */
369 #define UMA_ZFLAG_CACHEONLY 0x80000000 /* Don't ask VM for buckets. */
371 #define UMA_ZFLAG_INHERIT \
372 (UMA_ZFLAG_INTERNAL | UMA_ZFLAG_CACHEONLY | UMA_ZFLAG_BUCKET)
374 static inline uma_keg_t
375 zone_first_keg(uma_zone_t zone)
379 klink = LIST_FIRST(&zone->uz_kegs);
380 return (klink != NULL) ? klink->kl_keg : NULL;
386 /* Internal prototypes */
387 static __inline uma_slab_t hash_sfind(struct uma_hash *hash, uint8_t *data);
388 void *uma_large_malloc(vm_size_t size, int wait);
389 void *uma_large_malloc_domain(vm_size_t size, int domain, int wait);
390 void uma_large_free(uma_slab_t slab);
394 #define KEG_LOCK_INIT(k, lc) \
397 mtx_init(&(k)->uk_lock, (k)->uk_name, \
398 (k)->uk_name, MTX_DEF | MTX_DUPOK); \
400 mtx_init(&(k)->uk_lock, (k)->uk_name, \
401 "UMA zone", MTX_DEF | MTX_DUPOK); \
404 #define KEG_LOCK_FINI(k) mtx_destroy(&(k)->uk_lock)
405 #define KEG_LOCK(k) mtx_lock(&(k)->uk_lock)
406 #define KEG_UNLOCK(k) mtx_unlock(&(k)->uk_lock)
408 #define ZONE_LOCK_INIT(z, lc) \
411 mtx_init(&(z)->uz_lock, (z)->uz_name, \
412 (z)->uz_name, MTX_DEF | MTX_DUPOK); \
414 mtx_init(&(z)->uz_lock, (z)->uz_name, \
415 "UMA zone", MTX_DEF | MTX_DUPOK); \
418 #define ZONE_LOCK(z) mtx_lock((z)->uz_lockptr)
419 #define ZONE_TRYLOCK(z) mtx_trylock((z)->uz_lockptr)
420 #define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lockptr)
421 #define ZONE_LOCK_FINI(z) mtx_destroy(&(z)->uz_lock)
424 * Find a slab within a hash table. This is used for OFFPAGE zones to lookup
425 * the slab structure.
428 * hash The hash table to search.
429 * data The base page of the item.
432 * A pointer to a slab if successful, else NULL.
434 static __inline uma_slab_t
435 hash_sfind(struct uma_hash *hash, uint8_t *data)
440 hval = UMA_HASH(hash, data);
442 SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
443 if ((uint8_t *)slab->us_data == data)
449 static __inline uma_slab_t
450 vtoslab(vm_offset_t va)
454 p = PHYS_TO_VM_PAGE(pmap_kextract(va));
455 return ((uma_slab_t)p->plinks.s.pv);
459 vsetslab(vm_offset_t va, uma_slab_t slab)
463 p = PHYS_TO_VM_PAGE(pmap_kextract(va));
464 p->plinks.s.pv = slab;
468 * The following two functions may be defined by architecture specific code
469 * if they can provide more efficient allocation functions. This is useful
470 * for using direct mapped addresses.
472 void *uma_small_alloc(uma_zone_t zone, vm_size_t bytes, int domain,
473 uint8_t *pflag, int wait);
474 void uma_small_free(void *mem, vm_size_t size, uint8_t flags);
476 /* Set a global soft limit on UMA managed memory. */
477 void uma_set_limit(unsigned long limit);
480 #endif /* VM_UMA_INT_H */