source: mainline/generic/src/mm/slab.c@ 4e147a6

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since 4e147a6 was 4e147a6, checked in by Ondrej Palkovsky <ondrap@…>, 20 years ago

Skeleton of SLAB allocator.
  • Property mode set to 100644
File size: 10.6 KB
Line 
1/*
2 * Copyright (C) 2006 Ondrej Palkovsky
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 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - 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 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <synch/spinlock.h>
30#include <mm/slab.h>
31#include <list.h>
32#include <memstr.h>
33#include <align.h>
34#include <mm/heap.h>
35#include <config.h>
36#include <print.h>
37#include <arch.h>
38#include <panic.h>
39
40SPINLOCK_INITIALIZE(slab_cache_lock);
41LIST_INITIALIZE(slab_cache_list);
42
43slab_cache_t mag_cache;
44
45/**************************************/
46/* SLAB low level functions */
47
48
49/**
50 * Return object to slab and call a destructor
51 *
52 * @return Number of freed pages
53 */
54static count_t slab_obj_destroy(slab_cache_t *cache, void *obj)
55{
56 return 0;
57}
58
59
60/**
61 * Take new object from slab or create new if needed
62 *
63 * @return Object address or null
64 */
65static void * slab_obj_create(slab_cache_t *cache, int flags)
66{
67 return NULL;
68}
69
70/**************************************/
71/* CPU-Cache slab functions */
72
73/**
74 * Free all objects in magazine and free memory associated with magazine
75 *
76 * Assume cpu->lock is locked
77 *
78 * @return Number of freed pages
79 */
80static count_t magazine_destroy(slab_cache_t *cache,
81 slab_magazine_t *mag)
82{
83 int i;
84 count_t frames = 0;
85
86 for (i=0;i < mag->busy; i++)
87 frames += slab_obj_destroy(cache, mag->objs[i]);
88
89 slab_free(&mag_cache, mag);
90
91 return frames;
92}
93
94/**
95 * Try to find object in CPU-cache magazines
96 *
97 * @return Pointer to object or NULL if not available
98 */
99static void * magazine_obj_get(slab_cache_t *cache)
100{
101 slab_magazine_t *mag;
102
103 spinlock_lock(&cache->mag_cache[CPU->id].lock);
104
105 mag = cache->mag_cache[CPU->id].current;
106 if (!mag)
107 goto out;
108
109 if (!mag->busy) {
110 /* If current is empty && last exists && not empty, exchange */
111 if (cache->mag_cache[CPU->id].last \
112 && cache->mag_cache[CPU->id].last->busy) {
113 cache->mag_cache[CPU->id].current = cache->mag_cache[CPU->id].last;
114 cache->mag_cache[CPU->id].last = mag;
115 mag = cache->mag_cache[CPU->id].current;
116 goto gotit;
117 }
118 /* If still not busy, exchange current with some frome
119 * other full magazines */
120 spinlock_lock(&cache->lock);
121 if (list_empty(&cache->magazines)) {
122 spinlock_unlock(&cache->lock);
123 goto out;
124 }
125 /* Free current magazine and take one from list */
126 slab_free(&mag_cache, mag);
127 mag = list_get_instance(cache->magazines.next,
128 slab_magazine_t,
129 link);
130 list_remove(&mag->link);
131
132 spinlock_unlock(&cache->lock);
133 }
134gotit:
135 spinlock_unlock(&cache->mag_cache[CPU->id].lock);
136 return mag->objs[--mag->busy];
137out:
138 spinlock_unlock(&cache->mag_cache[CPU->id].lock);
139 return NULL;
140}
141
142/**
143 * Put object into CPU-cache magazine
144 *
145 * We have 2 magazines bound to processor.
146 * First try the current.
147 * If full, try the last.
148 * If full, put to magazines list.
149 * allocate new, exchange last & current
150 *
151 * @return 0 - success, -1 - could not get memory
152 */
153static int magazine_obj_put(slab_cache_t *cache, void *obj)
154{
155 slab_magazine_t *mag;
156
157 spinlock_lock(&cache->mag_cache[CPU->id].lock);
158
159 mag = cache->mag_cache[CPU->id].current;
160 if (!mag) {
161 /* We do not want to sleep just because of caching */
162 /* Especially we do not want reclaiming to start, as
163 * this would deadlock */
164 mag = slab_alloc(&mag_cache, SLAB_ATOMIC | SLAB_NO_RECLAIM);
165 if (!mag) /* Allocation failed, give up on caching */
166 goto errout;
167
168 cache->mag_cache[CPU->id].current = mag;
169 mag->size = SLAB_MAG_SIZE;
170 mag->busy = 0;
171 } else if (mag->busy == mag->size) {
172 /* If the last is full | empty, allocate new */
173 mag = cache->mag_cache[CPU->id].last;
174 if (!mag || mag->size == mag->busy) {
175 if (mag)
176 list_prepend(&cache->magazines, &mag->link);
177
178 mag = slab_alloc(&mag_cache, SLAB_ATOMIC | SLAB_NO_RECLAIM);
179 if (!mag)
180 goto errout;
181
182 mag->size = SLAB_MAG_SIZE;
183 mag->busy = 0;
184 cache->mag_cache[CPU->id].last = mag;
185 }
186 /* Exchange the 2 */
187 cache->mag_cache[CPU->id].last = cache->mag_cache[CPU->id].current;
188 cache->mag_cache[CPU->id].current = mag;
189 }
190 mag->objs[mag->busy++] = obj;
191
192 spinlock_unlock(&cache->mag_cache[CPU->id].lock);
193 return 0;
194errout:
195 spinlock_unlock(&cache->mag_cache[CPU->id].lock);
196 return -1;
197}
198
199
200/**************************************/
201/* Top level SLAB functions */
202
203/** Initialize allocated memory as a slab cache */
204static void
205_slab_cache_create(slab_cache_t *cache,
206 char *name,
207 size_t size,
208 size_t align,
209 int (*constructor)(void *obj, int kmflag),
210 void (*destructor)(void *obj),
211 int flags)
212{
213 int i;
214
215 memsetb((__address)cache, sizeof(*cache), 0);
216 cache->name = name;
217 cache->align = align;
218
219 cache->size = ALIGN_UP(size, align);
220
221 cache->constructor = constructor;
222 cache->destructor = destructor;
223 cache->flags = flags;
224
225 list_initialize(&cache->full_slabs);
226 list_initialize(&cache->partial_slabs);
227 list_initialize(&cache->magazines);
228 spinlock_initialize(&cache->lock, "cachelock");
229 if (! cache->flags & SLAB_CACHE_NOMAGAZINE) {
230 for (i=0; i< config.cpu_count; i++)
231 spinlock_initialize(&cache->mag_cache[i].lock,
232 "cpucachelock");
233 }
234
235 /* Compute slab sizes, object counts in slabs etc. */
236 if (cache->size < SLAB_INSIDE_SIZE)
237 cache->flags |= SLAB_CACHE_SLINSIDE;
238
239
240
241 spinlock_lock(&slab_cache_lock);
242
243 list_append(&cache->link, &slab_cache_list);
244
245 spinlock_unlock(&slab_cache_lock);
246}
247
248/** Create slab cache */
249slab_cache_t * slab_cache_create(char *name,
250 size_t size,
251 size_t align,
252 int (*constructor)(void *obj, int kmflag),
253 void (*destructor)(void *obj),
254 int flags)
255{
256 slab_cache_t *cache;
257
258 cache = malloc(sizeof(*cache) + config.cpu_count*sizeof(cache->mag_cache[0]));
259 _slab_cache_create(cache, name, size, align, constructor, destructor,
260 flags);
261 return cache;
262}
263
264/**
265 * Reclaim space occupied by objects that are already free
266 *
267 * @param flags If contains SLAB_RECLAIM_ALL, do aggressive freeing
268 * @return Number of freed pages
269 */
270static count_t _slab_reclaim(slab_cache_t *cache, int flags)
271{
272 int i;
273 slab_magazine_t *mag;
274 link_t *cur;
275 count_t frames = 0;
276
277 if (cache->flags & SLAB_CACHE_NOMAGAZINE)
278 return 0; /* Nothing to do */
279
280 /* First lock all cpu caches, then the complete cache lock */
281 for (i=0; i < config.cpu_count; i++)
282 spinlock_lock(&cache->mag_cache[i].lock);
283 spinlock_lock(&cache->lock);
284
285 if (flags & SLAB_RECLAIM_ALL) {
286 /* Destroy CPU magazines */
287 for (i=0; i<config.cpu_count; i++) {
288 mag = cache->mag_cache[i].current;
289 if (mag)
290 frames += magazine_destroy(cache, mag);
291 cache->mag_cache[i].current = NULL;
292
293 mag = cache->mag_cache[i].last;
294 if (mag)
295 frames += magazine_destroy(cache, mag);
296 cache->mag_cache[i].last = NULL;
297 }
298 /* Destroy full magazines */
299 cur=cache->magazines.next;
300 while (cur!=&cache->magazines) {
301 mag = list_get_instance(cur, slab_magazine_t, link);
302
303 cur = cur->next;
304 list_remove(cur->prev);
305 frames += magazine_destroy(cache,mag);
306 }
307 }
308
309 spinlock_unlock(&cache->lock);
310 for (i=0; i < config.cpu_count; i++)
311 spinlock_unlock(&cache->mag_cache[i].lock);
312
313 return frames;
314}
315
316/** Check that there are no slabs and remove cache from system */
317void slab_cache_destroy(slab_cache_t *cache)
318{
319 /* Do not lock anything, we assume the software is correct and
320 * does not touch the cache when it decides to destroy it */
321
322 /* Destroy all magazines */
323 _slab_reclaim(cache, SLAB_RECLAIM_ALL);
324
325 /* All slabs must be empty */
326 if (!list_empty(&cache->full_slabs) \
327 || !list_empty(&cache->partial_slabs))
328 panic("Destroying cache that is not empty.");
329
330 spinlock_lock(&slab_cache_lock);
331 list_remove(&cache->link);
332 spinlock_unlock(&slab_cache_lock);
333
334 free(cache);
335}
336
337/** Allocate new object from cache - if no flags given, always returns
338 memory */
339void * slab_alloc(slab_cache_t *cache, int flags)
340{
341 ipl_t ipl;
342 void *result = NULL;
343
344 /* Disable interrupts to avoid deadlocks with interrupt handlers */
345 ipl = interrupts_disable();
346
347 if (!cache->flags & SLAB_CACHE_NOMAGAZINE)
348 result = magazine_obj_get(cache);
349
350 if (!result)
351 result = slab_obj_create(cache, flags);
352
353 interrupts_restore(ipl);
354
355 return result;
356}
357
358/** Return object to cache */
359void slab_free(slab_cache_t *cache, void *obj)
360{
361 ipl_t ipl;
362
363 ipl = interrupts_disable();
364
365 if (cache->flags & SLAB_CACHE_NOMAGAZINE)
366 slab_obj_destroy(cache, obj);
367 else {
368 if (magazine_obj_put(cache, obj)) /* If magazine put failed */
369 slab_obj_destroy(cache, obj);
370 }
371 interrupts_restore(ipl);
372}
373
374/* Go through all caches and reclaim what is possible */
375count_t slab_reclaim(int flags)
376{
377 slab_cache_t *cache;
378 link_t *cur;
379 count_t frames = 0;
380
381 spinlock_lock(&slab_cache_lock);
382
383 for (cur = slab_cache_list.next;cur!=&slab_cache_list; cur=cur->next) {
384 cache = list_get_instance(cur, slab_cache_t, link);
385 frames += _slab_reclaim(cache, flags);
386 }
387
388 spinlock_unlock(&slab_cache_lock);
389
390 return frames;
391}
392
393
394/* Print list of slabs */
395void slab_print_list(void)
396{
397 slab_cache_t *cache;
398 link_t *cur;
399
400 spinlock_lock(&slab_cache_lock);
401 printf("SLAB name\tObj size\n");
402 for (cur = slab_cache_list.next;cur!=&slab_cache_list; cur=cur->next) {
403 cache = list_get_instance(cur, slab_cache_t, link);
404 printf("%s\t%d\n", cache->name, cache->size);
405 }
406 spinlock_unlock(&slab_cache_lock);
407}
408
409void slab_cache_init(void)
410{
411 /* Initialize magazine cache */
412 _slab_cache_create(&mag_cache,
413 "slab_magazine",
414 sizeof(slab_magazine_t)+SLAB_MAG_SIZE*sizeof(void*),
415 sizeof(__address),
416 NULL, NULL,
417 SLAB_CACHE_NOMAGAZINE);
418
419 /* Initialize structures for malloc */
420}
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