1 /* $Id: alloccache.c 2633 2012-09-08 23:18:59Z bird $ */
2 /** @file
3 * alloccache - Fixed sized allocation cache.
4 *
5 * The rational for using an allocation cache, is that it is way faster
6 * than malloc+free on most systems. It may be more efficient as well,
7 * depending on the way the heap implementes small allocations. Also,
8 * with the incdep.c code being threaded, all heaps (except for MSC)
9 * ran into severe lock contention issues since both the main thread
10 * and the incdep worker thread was allocating a crazy amount of tiny
11 * allocations (struct dep, struct nameseq, ++).
12 *
13 * Darwin also showed a significant amount of time spent just executing
14 * free(), which is kind of silly. The alloccache helps a bit here too.
15 */
16
17 /*
18 * Copyright (c) 2008-2010 knut st. osmundsen <bird-kBuild-spamx@anduin.net>
19 *
20 * This file is part of kBuild.
21 *
22 * kBuild is free software; you can redistribute it and/or modify
23 * it under the terms of the GNU General Public License as published by
24 * the Free Software Foundation; either version 3 of the License, or
25 * (at your option) any later version.
26 *
27 * kBuild is distributed in the hope that it will be useful,
28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
30 * GNU General Public License for more details.
31 *
32 * You should have received a copy of the GNU General Public License
33 * along with kBuild. If not, see <http://www.gnu.org/licenses/>
34 *
35 */
36
37 /*******************************************************************************
38 * Header Files *
39 *******************************************************************************/
40 #include "make.h"
41 #include "dep.h"
42 #include "debug.h"
43 #include <assert.h>
44
45
46 #ifdef CONFIG_WITH_ALLOC_CACHES
47
48 /* Free am item.
49 This was not inlined because of aliasing issues arrising with GCC.
50 It is also in a separate file for this reason (it used to be in misc.c
51 but since free_dep_chain() was using it there, we ran the risk of it
52 being inlined and gcc screwing up). */
53 void
alloccache_free(struct alloccache * cache,void * item)54 alloccache_free (struct alloccache *cache, void *item)
55 {
56 #ifndef CONFIG_WITH_ALLOCCACHE_DEBUG
57 struct alloccache_free_ent *f = (struct alloccache_free_ent *)item;
58 # if 0 /*ndef NDEBUG*/
59 struct alloccache_free_ent *c;
60 unsigned int i = 0;
61 for (c = cache->free_head; c != NULL; c = c->next, i++)
62 MY_ASSERT_MSG (c != f && i < 0x10000000,
63 ("i=%u total_count=%u\n", i, cache->total_count));
64 # endif
65
66 f->next = cache->free_head;
67 cache->free_head = f;
68 MAKE_STATS(cache->free_count++;);
69 #else
70 free(item);
71 #endif
72 }
73
74 /* Default allocator. */
75 static void *
alloccache_default_grow_alloc(void * ignore,unsigned int size)76 alloccache_default_grow_alloc(void *ignore, unsigned int size)
77 {
78 return xmalloc (size);
79 }
80
81 /* Worker for growing the cache. */
82 struct alloccache_free_ent *
alloccache_alloc_grow(struct alloccache * cache)83 alloccache_alloc_grow (struct alloccache *cache)
84 {
85 #ifndef CONFIG_WITH_ALLOCCACHE_DEBUG
86 void *item;
87 unsigned int items = (64*1024 - 32) / cache->size;
88 cache->free_start = cache->grow_alloc (cache->grow_arg, items * cache->size);
89 cache->free_end = cache->free_start + items * cache->size;
90 cache->total_count+= items;
91
92 # ifndef NDEBUG /* skip the first item so the heap can detect free(). */
93 cache->total_count--;
94 cache->free_start += cache->size;
95 # endif
96
97 item = cache->free_start;
98 cache->free_start += cache->size;
99 /* caller counts */
100 return (struct alloccache_free_ent *)item;
101 #else
102 return (struct alloccache_free_ent *)xmalloc(cache->size);
103 #endif
104 }
105
106 /* List of alloc caches, for printing. */
107 static struct alloccache *alloccache_head = NULL;
108
109 /* Initializes an alloc cache */
110 void
alloccache_init(struct alloccache * cache,unsigned int size,const char * name,void * (* grow_alloc)(void * grow_arg,unsigned int size),void * grow_arg)111 alloccache_init (struct alloccache *cache, unsigned int size, const char *name,
112 void *(*grow_alloc)(void *grow_arg, unsigned int size), void *grow_arg)
113 {
114 unsigned act_size;
115
116 /* ensure OK alignment and min sizeof (struct alloccache_free_ent). */
117 if (size <= sizeof (struct alloccache_free_ent))
118 act_size = sizeof (struct alloccache_free_ent);
119 else if (size <= 32)
120 {
121 act_size = 4;
122 while (act_size < size)
123 act_size <<= 1;
124 }
125 else
126 act_size = (size + 31U) & ~(size_t)31;
127
128 /* align the structure. */
129 cache->free_start = NULL;
130 cache->free_end = NULL;
131 cache->free_head = NULL;
132 cache->size = act_size;
133 cache->total_count = 0;
134 cache->alloc_count = 0;
135 cache->free_count = 0;
136 cache->name = name;
137 cache->grow_arg = grow_arg;
138 cache->grow_alloc = grow_alloc ? grow_alloc : alloccache_default_grow_alloc;
139
140 /* link it. */
141 cache->next = alloccache_head;
142 alloccache_head = cache;
143 }
144
145 /* Terminate an alloc cache, free all the memory it contains. */
146 void
alloccache_term(struct alloccache * cache,void (* term_free)(void * term_arg,void * ptr,unsigned int size),void * term_arg)147 alloccache_term (struct alloccache *cache,
148 void (*term_free)(void *term_arg, void *ptr, unsigned int size), void *term_arg)
149 {
150 /*cache->size = 0;*/
151 (void)cache;
152 (void)term_free;
153 (void)term_arg;
154 /* FIXME: Implement memory segment tracking and cleanup. */
155 }
156
157 /* Joins to caches, unlinking the 2nd one. */
158 void
alloccache_join(struct alloccache * cache,struct alloccache * eat)159 alloccache_join (struct alloccache *cache, struct alloccache *eat)
160 {
161 assert (cache->size == eat->size);
162
163 #if 0 /* probably a waste of time */ /* FIXME: Optimize joining, avoid all list walking. */
164 /* add the free list... */
165 if (eat->free_head)
166 {
167 unsigned int eat_in_use = eat->alloc_count - eat->free_count;
168 unsigned int dst_in_use = cache->alloc_count - cache->free_count;
169 if (!cache->free_head)
170 cache->free_head = eat->free_head;
171 else if (eat->total_count - eat_in_use < cache->total_count - dst_ins_use)
172 {
173 struct alloccache_free_ent *last = eat->free_head;
174 while (last->next)
175 last = last->next;
176 last->next = cache->free_head;
177 cache->free_head = eat->free_head;
178 }
179 else
180 {
181 struct alloccache_free_ent *last = cache->free_head;
182 while (last->next)
183 last = last->next;
184 last->next = eat->free_head;
185 }
186 }
187
188 /* ... and the free space. */
189 while (eat->free_start != eat->free_end)
190 {
191 struct alloccache_free_ent *f = (struct alloccache_free_ent *)eat->free_start;
192 eat->free_start += eat->size;
193 f->next = cache->free_head;
194 cache->free_head = f;
195 }
196
197 /* and statistics */
198 cache->alloc_count += eat->alloc_count;
199 cache->free_count += eat->free_count;
200 #else
201 /* and statistics */
202 cache->alloc_count += eat->alloc_count;
203 cache->free_count += eat->free_count;
204 #endif
205 cache->total_count += eat->total_count;
206
207 /* unlink and disable the eat cache */
208 if (alloccache_head == eat)
209 alloccache_head = eat->next;
210 else
211 {
212 struct alloccache *cur = alloccache_head;
213 while (cur->next != eat)
214 cur = cur->next;
215 assert (cur && cur->next == eat);
216 cur->next = eat->next;
217 }
218
219 eat->size = 0;
220 eat->free_end = eat->free_start = NULL;
221 eat->free_head = NULL;
222 }
223
224 /* Print one alloc cache. */
225 void
alloccache_print(struct alloccache * cache)226 alloccache_print (struct alloccache *cache)
227 {
228 printf (_("\n# Alloc Cache: %s\n"
229 "# Items: size = %-3u total = %-6u"),
230 cache->name, cache->size, cache->total_count);
231 MAKE_STATS(printf (_(" in-use = %-6lu"),
232 cache->alloc_count - cache->free_count););
233 MAKE_STATS(printf (_("\n# alloc calls = %-7lu free calls = %-7lu"),
234 cache->alloc_count, cache->free_count););
235 printf ("\n");
236 }
237
238 /* Print all alloc caches. */
239 void
alloccache_print_all(void)240 alloccache_print_all (void)
241 {
242 struct alloccache *cur;
243 puts ("");
244 for (cur = alloccache_head; cur; cur = cur->next)
245 alloccache_print (cur);
246 }
247
248 #endif /* CONFIG_WITH_ALLOC_CACHES */
249
250