FreeBSD/Linux Kernel Cross Reference
sys/vm/uma_int.h
1 /*-
2 * Copyright (c) 2002-2005, 2009, 2013 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 #include <sys/_bitset.h>
32 #include <sys/_task.h>
33
34 /*
35 * This file includes definitions, structures, prototypes, and inlines that
36 * should not be used outside of the actual implementation of UMA.
37 */
38
39 /*
40 * Here's a quick description of the relationship between the objects:
41 *
42 * Kegs contain lists of slabs which are stored in either the full bin, empty
43 * bin, or partially allocated bin, to reduce fragmentation. They also contain
44 * the user supplied value for size, which is adjusted for alignment purposes
45 * and rsize is the result of that. The Keg also stores information for
46 * managing a hash of page addresses that maps pages to uma_slab_t structures
47 * for pages that don't have embedded uma_slab_t's.
48 *
49 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
50 * be allocated off the page from a special slab zone. The free list within a
51 * slab is managed with a bitmask. For item sizes that would yield more than
52 * 10% memory waste we potentially allocate a separate uma_slab_t if this will
53 * improve the number of items per slab that will fit.
54 *
55 * The only really gross cases, with regards to memory waste, are for those
56 * items that are just over half the page size. You can get nearly 50% waste,
57 * so you fall back to the memory footprint of the power of two allocator. I
58 * have looked at memory allocation sizes on many of the machines available to
59 * me, and there does not seem to be an abundance of allocations at this range
60 * so at this time it may not make sense to optimize for it. This can, of
61 * course, be solved with dynamic slab sizes.
62 *
63 * Kegs may serve multiple Zones but by far most of the time they only serve
64 * one. When a Zone is created, a Keg is allocated and setup for it. While
65 * the backing Keg stores slabs, the Zone caches Buckets of items allocated
66 * from the slabs. Each Zone is equipped with an init/fini and ctor/dtor
67 * pair, as well as with its own set of small per-CPU caches, layered above
68 * the Zone's general Bucket cache.
69 *
70 * The PCPU caches are protected by critical sections, and may be accessed
71 * safely only from their associated CPU, while the Zones backed by the same
72 * Keg all share a common Keg lock (to coalesce contention on the backing
73 * slabs). The backing Keg typically only serves one Zone but in the case of
74 * multiple Zones, one of the Zones is considered the Master Zone and all
75 * Zone-related stats from the Keg are done in the Master Zone. For an
76 * example of a Multi-Zone setup, refer to the Mbuf allocation code.
77 */
78
79 /*
80 * This is the representation for normal (Non OFFPAGE slab)
81 *
82 * i == item
83 * s == slab pointer
84 *
85 * <---------------- Page (UMA_SLAB_SIZE) ------------------>
86 * ___________________________________________________________
87 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ |
88 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
89 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________||
90 * |___________________________________________________________|
91 *
92 *
93 * This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
94 *
95 * ___________________________________________________________
96 * | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
97 * ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |
98 * ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |
99 * |___________________________________________________________|
100 * ___________ ^
101 * |slab header| |
102 * |___________|---*
103 *
104 */
105
106 #ifndef VM_UMA_INT_H
107 #define VM_UMA_INT_H
108
109 #define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */
110 #define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */
111 #define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */
112
113 #define UMA_BOOT_PAGES 64 /* Pages allocated for startup */
114 #define UMA_BOOT_PAGES_ZONES 32 /* Multiplier for pages to reserve */
115 /* if uma_zone > PAGE_SIZE */
116
117 /* Max waste percentage before going to off page slab management */
118 #define UMA_MAX_WASTE 10
119
120 /*
121 * I doubt there will be many cases where this is exceeded. This is the initial
122 * size of the hash table for uma_slabs that are managed off page. This hash
123 * does expand by powers of two. Currently it doesn't get smaller.
124 */
125 #define UMA_HASH_SIZE_INIT 32
126
127 /*
128 * I should investigate other hashing algorithms. This should yield a low
129 * number of collisions if the pages are relatively contiguous.
130 */
131
132 #define UMA_HASH(h, s) ((((uintptr_t)s) >> UMA_SLAB_SHIFT) & (h)->uh_hashmask)
133
134 #define UMA_HASH_INSERT(h, s, mem) \
135 SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \
136 (mem))], (s), us_hlink)
137 #define UMA_HASH_REMOVE(h, s, mem) \
138 SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \
139 (mem))], (s), uma_slab, us_hlink)
140
141 /* Hash table for freed address -> slab translation */
142
143 SLIST_HEAD(slabhead, uma_slab);
144
145 struct uma_hash {
146 struct slabhead *uh_slab_hash; /* Hash table for slabs */
147 u_int uh_hashsize; /* Current size of the hash table */
148 u_int uh_hashmask; /* Mask used during hashing */
149 };
150
151 /*
152 * align field or structure to cache line
153 */
154 #if defined(__amd64__)
155 #define UMA_ALIGN __aligned(CACHE_LINE_SIZE)
156 #else
157 #define UMA_ALIGN
158 #endif
159
160 /*
161 * Structures for per cpu queues.
162 */
163
164 struct uma_bucket {
165 LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */
166 int16_t ub_cnt; /* Count of free items. */
167 int16_t ub_entries; /* Max items. */
168 void *ub_bucket[]; /* actual allocation storage */
169 };
170
171 typedef struct uma_bucket * uma_bucket_t;
172
173 struct uma_cache {
174 uma_bucket_t uc_freebucket; /* Bucket we're freeing to */
175 uma_bucket_t uc_allocbucket; /* Bucket to allocate from */
176 uint64_t uc_allocs; /* Count of allocations */
177 uint64_t uc_frees; /* Count of frees */
178 } UMA_ALIGN;
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 struct mtx_padalign uk_lock; /* Lock for the keg */
190 struct uma_hash uk_hash;
191
192 LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */
193 LIST_HEAD(,uma_slab) uk_part_slab; /* partially allocated slabs */
194 LIST_HEAD(,uma_slab) uk_free_slab; /* empty slab list */
195 LIST_HEAD(,uma_slab) uk_full_slab; /* full slabs */
196
197 uint32_t uk_align; /* Alignment mask */
198 uint32_t uk_pages; /* Total page count */
199 uint32_t uk_free; /* Count of items free in slabs */
200 uint32_t uk_reserve; /* Number of reserved items. */
201 uint32_t uk_size; /* Requested size of each item */
202 uint32_t uk_rsize; /* Real size of each item */
203 uint32_t uk_maxpages; /* Maximum number of pages to alloc */
204
205 uma_init uk_init; /* Keg's init routine */
206 uma_fini uk_fini; /* Keg's fini routine */
207 uma_alloc uk_allocf; /* Allocation function */
208 uma_free uk_freef; /* Free routine */
209
210 u_long uk_offset; /* Next free offset from base KVA */
211 vm_offset_t uk_kva; /* Zone base KVA */
212 uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */
213
214 uint32_t uk_pgoff; /* Offset to uma_slab struct */
215 uint16_t uk_ppera; /* pages per allocation from backend */
216 uint16_t uk_ipers; /* Items per slab */
217 uint32_t uk_flags; /* Internal flags */
218
219 /* Least used fields go to the last cache line. */
220 const char *uk_name; /* Name of creating zone. */
221 LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */
222 };
223 typedef struct uma_keg * uma_keg_t;
224
225 /*
226 * Free bits per-slab.
227 */
228 #define SLAB_SETSIZE (PAGE_SIZE / UMA_SMALLEST_UNIT)
229 BITSET_DEFINE(slabbits, SLAB_SETSIZE);
230
231 /*
232 * The slab structure manages a single contiguous allocation from backing
233 * store and subdivides it into individually allocatable items.
234 */
235 struct uma_slab {
236 uma_keg_t us_keg; /* Keg we live in */
237 union {
238 LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */
239 unsigned long _us_size; /* Size of allocation */
240 } us_type;
241 SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */
242 uint8_t *us_data; /* First item */
243 struct slabbits us_free; /* Free bitmask. */
244 #ifdef INVARIANTS
245 struct slabbits us_debugfree; /* Debug bitmask. */
246 #endif
247 uint16_t us_freecount; /* How many are free? */
248 uint8_t us_flags; /* Page flags see uma.h */
249 uint8_t us_pad; /* Pad to 32bits, unused. */
250 };
251
252 #define us_link us_type._us_link
253 #define us_size us_type._us_size
254
255 typedef struct uma_slab * uma_slab_t;
256 typedef uma_slab_t (*uma_slaballoc)(uma_zone_t, uma_keg_t, int);
257
258 struct uma_klink {
259 LIST_ENTRY(uma_klink) kl_link;
260 uma_keg_t kl_keg;
261 };
262 typedef struct uma_klink *uma_klink_t;
263
264 /*
265 * Zone management structure
266 *
267 * TODO: Optimize for cache line size
268 *
269 */
270 struct uma_zone {
271 struct mtx_padalign uz_lock; /* Lock for the zone */
272 struct mtx_padalign *uz_lockptr;
273 const char *uz_name; /* Text name of the zone */
274
275 LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */
276 LIST_HEAD(,uma_bucket) uz_buckets; /* full buckets */
277
278 LIST_HEAD(,uma_klink) uz_kegs; /* List of kegs. */
279 struct uma_klink uz_klink; /* klink for first keg. */
280
281 uma_slaballoc uz_slab; /* Allocate a slab from the backend. */
282 uma_ctor uz_ctor; /* Constructor for each allocation */
283 uma_dtor uz_dtor; /* Destructor */
284 uma_init uz_init; /* Initializer for each item */
285 uma_fini uz_fini; /* Finalizer for each item. */
286 uma_import uz_import; /* Import new memory to cache. */
287 uma_release uz_release; /* Release memory from cache. */
288 void *uz_arg; /* Import/release argument. */
289
290 uint32_t uz_flags; /* Flags inherited from kegs */
291 uint32_t uz_size; /* Size inherited from kegs */
292
293 volatile u_long uz_allocs UMA_ALIGN; /* Total number of allocations */
294 volatile u_long uz_fails; /* Total number of alloc failures */
295 volatile u_long uz_frees; /* Total number of frees */
296 uint64_t uz_sleeps; /* Total number of alloc sleeps */
297 uint16_t uz_count; /* Amount of items in full bucket */
298 uint16_t uz_count_min; /* Minimal amount of items there */
299
300 /* The next two fields are used to print a rate-limited warnings. */
301 const char *uz_warning; /* Warning to print on failure */
302 struct timeval uz_ratecheck; /* Warnings rate-limiting */
303
304 struct task uz_maxaction; /* Task to run when at limit */
305
306 /*
307 * This HAS to be the last item because we adjust the zone size
308 * based on NCPU and then allocate the space for the zones.
309 */
310 struct uma_cache uz_cpu[1]; /* Per cpu caches */
311 };
312
313 /*
314 * These flags must not overlap with the UMA_ZONE flags specified in uma.h.
315 */
316 #define UMA_ZFLAG_MULTI 0x04000000 /* Multiple kegs in the zone. */
317 #define UMA_ZFLAG_DRAINING 0x08000000 /* Running zone_drain. */
318 #define UMA_ZFLAG_BUCKET 0x10000000 /* Bucket zone. */
319 #define UMA_ZFLAG_INTERNAL 0x20000000 /* No offpage no PCPU. */
320 #define UMA_ZFLAG_FULL 0x40000000 /* Reached uz_maxpages */
321 #define UMA_ZFLAG_CACHEONLY 0x80000000 /* Don't ask VM for buckets. */
322
323 #define UMA_ZFLAG_INHERIT \
324 (UMA_ZFLAG_INTERNAL | UMA_ZFLAG_CACHEONLY | UMA_ZFLAG_BUCKET)
325
326 static inline uma_keg_t
327 zone_first_keg(uma_zone_t zone)
328 {
329 uma_klink_t klink;
330
331 klink = LIST_FIRST(&zone->uz_kegs);
332 return (klink != NULL) ? klink->kl_keg : NULL;
333 }
334
335 #undef UMA_ALIGN
336
337 #ifdef _KERNEL
338 /* Internal prototypes */
339 static __inline uma_slab_t hash_sfind(struct uma_hash *hash, uint8_t *data);
340 void *uma_large_malloc(vm_size_t size, int wait);
341 void uma_large_free(uma_slab_t slab);
342
343 /* Lock Macros */
344
345 #define KEG_LOCK_INIT(k, lc) \
346 do { \
347 if ((lc)) \
348 mtx_init(&(k)->uk_lock, (k)->uk_name, \
349 (k)->uk_name, MTX_DEF | MTX_DUPOK); \
350 else \
351 mtx_init(&(k)->uk_lock, (k)->uk_name, \
352 "UMA zone", MTX_DEF | MTX_DUPOK); \
353 } while (0)
354
355 #define KEG_LOCK_FINI(k) mtx_destroy(&(k)->uk_lock)
356 #define KEG_LOCK(k) mtx_lock(&(k)->uk_lock)
357 #define KEG_UNLOCK(k) mtx_unlock(&(k)->uk_lock)
358
359 #define ZONE_LOCK_INIT(z, lc) \
360 do { \
361 if ((lc)) \
362 mtx_init(&(z)->uz_lock, (z)->uz_name, \
363 (z)->uz_name, MTX_DEF | MTX_DUPOK); \
364 else \
365 mtx_init(&(z)->uz_lock, (z)->uz_name, \
366 "UMA zone", MTX_DEF | MTX_DUPOK); \
367 } while (0)
368
369 #define ZONE_LOCK(z) mtx_lock((z)->uz_lockptr)
370 #define ZONE_TRYLOCK(z) mtx_trylock((z)->uz_lockptr)
371 #define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lockptr)
372 #define ZONE_LOCK_FINI(z) mtx_destroy(&(z)->uz_lock)
373
374 /*
375 * Find a slab within a hash table. This is used for OFFPAGE zones to lookup
376 * the slab structure.
377 *
378 * Arguments:
379 * hash The hash table to search.
380 * data The base page of the item.
381 *
382 * Returns:
383 * A pointer to a slab if successful, else NULL.
384 */
385 static __inline uma_slab_t
386 hash_sfind(struct uma_hash *hash, uint8_t *data)
387 {
388 uma_slab_t slab;
389 u_int hval;
390
391 hval = UMA_HASH(hash, data);
392
393 SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
394 if ((uint8_t *)slab->us_data == data)
395 return (slab);
396 }
397 return (NULL);
398 }
399
400 static __inline uma_slab_t
401 vtoslab(vm_offset_t va)
402 {
403 vm_page_t p;
404
405 p = PHYS_TO_VM_PAGE(pmap_kextract(va));
406 return ((uma_slab_t)p->plinks.s.pv);
407 }
408
409 static __inline void
410 vsetslab(vm_offset_t va, uma_slab_t slab)
411 {
412 vm_page_t p;
413
414 p = PHYS_TO_VM_PAGE(pmap_kextract(va));
415 p->plinks.s.pv = slab;
416 }
417
418 /*
419 * The following two functions may be defined by architecture specific code
420 * if they can provide more efficient allocation functions. This is useful
421 * for using direct mapped addresses.
422 */
423 void *uma_small_alloc(uma_zone_t zone, vm_size_t bytes, uint8_t *pflag,
424 int wait);
425 void uma_small_free(void *mem, vm_size_t size, uint8_t flags);
426 #endif /* _KERNEL */
427
428 #endif /* VM_UMA_INT_H */
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