Commit | Line | Data |
---|---|---|
7ebd796f JA |
1 | /* |
2 | * Bitmap of bitmaps, where each layer is number-of-bits-per-word smaller than | |
3 | * the previous. Hence an 'axmap', since we axe each previous layer into a | |
4 | * much smaller piece. I swear, that is why it's named like that. It has | |
5 | * nothing to do with anything remotely narcissistic. | |
6 | * | |
7 | * A set bit at layer N indicates a full word at layer N-1, and so forth. As | |
de8f6de9 | 8 | * the bitmap becomes progressively more full, checking for existence |
7ebd796f JA |
9 | * becomes cheaper (since fewer layers are walked, making it a lot more |
10 | * cache friendly) and locating the next free space likewise. | |
11 | * | |
12 | * Axmaps get pretty close to optimal (1 bit per block) space usage, since | |
13 | * layers quickly diminish in size. Doing the size math is straight forward, | |
14 | * since we have log64(blocks) layers of maps. For 20000 blocks, overhead | |
15 | * is roughly 1.9%, or 1.019 bits per block. The number quickly converges | |
16 | * towards 1.0158, or 1.58% of overhead. | |
17 | */ | |
18 | #include <stdio.h> | |
19 | #include <stdlib.h> | |
20 | #include <string.h> | |
21 | #include <assert.h> | |
22 | ||
23 | #include "../arch/arch.h" | |
24 | #include "axmap.h" | |
7ebd796f JA |
25 | #include "../minmax.h" |
26 | ||
27 | #if BITS_PER_LONG == 64 | |
28 | #define UNIT_SHIFT 6 | |
29 | #elif BITS_PER_LONG == 32 | |
30 | #define UNIT_SHIFT 5 | |
31 | #else | |
32 | #error "Number of arch bits unknown" | |
33 | #endif | |
34 | ||
e6f735f0 | 35 | #define BLOCKS_PER_UNIT (1U << UNIT_SHIFT) |
7ebd796f JA |
36 | #define BLOCKS_PER_UNIT_MASK (BLOCKS_PER_UNIT - 1) |
37 | ||
38 | #define firstfree_valid(b) ((b)->first_free != (uint64_t) -1) | |
39 | ||
76dd186e JA |
40 | static const unsigned long bit_masks[] = { |
41 | 0x0000000000000000, 0x0000000000000001, 0x0000000000000003, 0x0000000000000007, | |
42 | 0x000000000000000f, 0x000000000000001f, 0x000000000000003f, 0x000000000000007f, | |
43 | 0x00000000000000ff, 0x00000000000001ff, 0x00000000000003ff, 0x00000000000007ff, | |
44 | 0x0000000000000fff, 0x0000000000001fff, 0x0000000000003fff, 0x0000000000007fff, | |
45 | 0x000000000000ffff, 0x000000000001ffff, 0x000000000003ffff, 0x000000000007ffff, | |
46 | 0x00000000000fffff, 0x00000000001fffff, 0x00000000003fffff, 0x00000000007fffff, | |
47 | 0x0000000000ffffff, 0x0000000001ffffff, 0x0000000003ffffff, 0x0000000007ffffff, | |
48 | 0x000000000fffffff, 0x000000001fffffff, 0x000000003fffffff, 0x000000007fffffff, | |
49 | 0x00000000ffffffff, | |
50 | #if BITS_PER_LONG == 64 | |
51 | 0x00000001ffffffff, 0x00000003ffffffff, 0x00000007ffffffff, 0x0000000fffffffff, | |
52 | 0x0000001fffffffff, 0x0000003fffffffff, 0x0000007fffffffff, 0x000000ffffffffff, | |
53 | 0x000001ffffffffff, 0x000003ffffffffff, 0x000007ffffffffff, 0x00000fffffffffff, | |
54 | 0x00001fffffffffff, 0x00003fffffffffff, 0x00007fffffffffff, 0x0000ffffffffffff, | |
55 | 0x0001ffffffffffff, 0x0003ffffffffffff, 0x0007ffffffffffff, 0x000fffffffffffff, | |
56 | 0x001fffffffffffff, 0x003fffffffffffff, 0x007fffffffffffff, 0x00ffffffffffffff, | |
57 | 0x01ffffffffffffff, 0x03ffffffffffffff, 0x07ffffffffffffff, 0x0fffffffffffffff, | |
58 | 0x1fffffffffffffff, 0x3fffffffffffffff, 0x7fffffffffffffff, 0xffffffffffffffff | |
59 | #endif | |
60 | }; | |
61 | ||
7ebd796f JA |
62 | struct axmap_level { |
63 | int level; | |
64 | unsigned long map_size; | |
65 | unsigned long *map; | |
66 | }; | |
67 | ||
68 | struct axmap { | |
69 | unsigned int nr_levels; | |
70 | struct axmap_level *levels; | |
71 | uint64_t first_free; | |
47d94b0b | 72 | uint64_t nr_bits; |
7ebd796f JA |
73 | }; |
74 | ||
76dd186e | 75 | static inline unsigned long ulog64(unsigned long val, unsigned int log) |
7ebd796f JA |
76 | { |
77 | while (log-- && val) | |
78 | val >>= UNIT_SHIFT; | |
79 | ||
80 | return val; | |
81 | } | |
82 | ||
83 | void axmap_reset(struct axmap *axmap) | |
84 | { | |
85 | int i; | |
86 | ||
87 | for (i = 0; i < axmap->nr_levels; i++) { | |
88 | struct axmap_level *al = &axmap->levels[i]; | |
89 | ||
90 | memset(al->map, 0, al->map_size * sizeof(unsigned long)); | |
91 | } | |
17f0fd39 JA |
92 | |
93 | axmap->first_free = 0; | |
7ebd796f JA |
94 | } |
95 | ||
96 | void axmap_free(struct axmap *axmap) | |
97 | { | |
98 | unsigned int i; | |
99 | ||
100 | if (!axmap) | |
101 | return; | |
102 | ||
103 | for (i = 0; i < axmap->nr_levels; i++) | |
aded30f7 | 104 | free(axmap->levels[i].map); |
7ebd796f | 105 | |
aded30f7 JA |
106 | free(axmap->levels); |
107 | free(axmap); | |
7ebd796f JA |
108 | } |
109 | ||
110 | struct axmap *axmap_new(unsigned long nr_bits) | |
111 | { | |
112 | struct axmap *axmap; | |
113 | unsigned int i, levels; | |
114 | ||
aded30f7 | 115 | axmap = malloc(sizeof(*axmap)); |
7ebd796f JA |
116 | if (!axmap) |
117 | return NULL; | |
118 | ||
119 | levels = 1; | |
120 | i = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
121 | while (i > 1) { | |
122 | i = (i + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
123 | levels++; | |
124 | } | |
125 | ||
126 | axmap->nr_levels = levels; | |
2404b2c3 | 127 | axmap->levels = calloc(axmap->nr_levels, sizeof(struct axmap_level)); |
47d94b0b | 128 | axmap->nr_bits = nr_bits; |
7ebd796f JA |
129 | |
130 | for (i = 0; i < axmap->nr_levels; i++) { | |
131 | struct axmap_level *al = &axmap->levels[i]; | |
132 | ||
133 | al->level = i; | |
134 | al->map_size = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
aded30f7 | 135 | al->map = malloc(al->map_size * sizeof(unsigned long)); |
7ebd796f JA |
136 | if (!al->map) |
137 | goto err; | |
138 | ||
139 | nr_bits = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
140 | } | |
141 | ||
142 | axmap_reset(axmap); | |
143 | return axmap; | |
144 | err: | |
145 | for (i = 0; i < axmap->nr_levels; i++) | |
146 | if (axmap->levels[i].map) | |
aded30f7 | 147 | free(axmap->levels[i].map); |
7ebd796f | 148 | |
aded30f7 | 149 | free(axmap->levels); |
bb1116fe | 150 | free(axmap); |
7ebd796f JA |
151 | return NULL; |
152 | } | |
153 | ||
e39c0676 JA |
154 | static bool axmap_handler(struct axmap *axmap, uint64_t bit_nr, |
155 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, | |
7ebd796f JA |
156 | void *), void *data) |
157 | { | |
158 | struct axmap_level *al; | |
edfca254 | 159 | uint64_t index = bit_nr; |
7ebd796f JA |
160 | int i; |
161 | ||
162 | for (i = 0; i < axmap->nr_levels; i++) { | |
7ebd796f JA |
163 | unsigned long offset = index >> UNIT_SHIFT; |
164 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
165 | ||
166 | al = &axmap->levels[i]; | |
167 | ||
168 | if (func(al, offset, bit, data)) | |
e39c0676 | 169 | return true; |
edfca254 JA |
170 | |
171 | if (index) | |
172 | index >>= UNIT_SHIFT; | |
7ebd796f JA |
173 | } |
174 | ||
e39c0676 | 175 | return false; |
7ebd796f JA |
176 | } |
177 | ||
e39c0676 | 178 | static bool axmap_handler_topdown(struct axmap *axmap, uint64_t bit_nr, |
c406445a | 179 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, void *)) |
7ebd796f | 180 | { |
76dd186e | 181 | int i; |
7ebd796f JA |
182 | |
183 | for (i = axmap->nr_levels - 1; i >= 0; i--) { | |
76dd186e | 184 | unsigned long index = ulog64(bit_nr, i); |
7ebd796f JA |
185 | unsigned long offset = index >> UNIT_SHIFT; |
186 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
187 | ||
41264298 | 188 | if (func(&axmap->levels[i], offset, bit, NULL)) |
e39c0676 | 189 | return true; |
7ebd796f JA |
190 | } |
191 | ||
e39c0676 | 192 | return false; |
7ebd796f JA |
193 | } |
194 | ||
e39c0676 | 195 | static bool axmap_clear_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
196 | unsigned int bit, void *unused) |
197 | { | |
198 | if (!(al->map[offset] & (1UL << bit))) | |
e39c0676 | 199 | return true; |
7ebd796f JA |
200 | |
201 | al->map[offset] &= ~(1UL << bit); | |
e39c0676 | 202 | return false; |
7ebd796f JA |
203 | } |
204 | ||
205 | void axmap_clear(struct axmap *axmap, uint64_t bit_nr) | |
206 | { | |
207 | axmap_handler(axmap, bit_nr, axmap_clear_fn, NULL); | |
2b2fa7f5 JA |
208 | |
209 | if (bit_nr < axmap->first_free) | |
210 | axmap->first_free = bit_nr; | |
7ebd796f JA |
211 | } |
212 | ||
213 | struct axmap_set_data { | |
214 | unsigned int nr_bits; | |
215 | unsigned int set_bits; | |
7ebd796f JA |
216 | }; |
217 | ||
e39c0676 | 218 | static bool axmap_set_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
219 | unsigned int bit, void *__data) |
220 | { | |
221 | struct axmap_set_data *data = __data; | |
222 | unsigned long mask, overlap; | |
223 | unsigned int nr_bits; | |
224 | ||
225 | nr_bits = min(data->nr_bits, BLOCKS_PER_UNIT - bit); | |
226 | ||
227 | mask = bit_masks[nr_bits] << bit; | |
228 | ||
229 | /* | |
230 | * Mask off any potential overlap, only sets contig regions | |
231 | */ | |
232 | overlap = al->map[offset] & mask; | |
bd71edce JA |
233 | if (overlap == mask) { |
234 | done: | |
235 | data->set_bits = 0; | |
e39c0676 | 236 | return true; |
bd71edce | 237 | } |
7ebd796f | 238 | |
8cd5a2fd JA |
239 | if (overlap) { |
240 | const int __bit = ffz(~overlap); | |
7ebd796f | 241 | |
c2e48e0e JA |
242 | nr_bits = __bit - bit; |
243 | if (!nr_bits) | |
bd71edce | 244 | goto done; |
8cd5a2fd | 245 | |
8cd5a2fd | 246 | mask = bit_masks[nr_bits] << bit; |
7ebd796f JA |
247 | } |
248 | ||
249 | assert(mask); | |
250 | assert(!(al->map[offset] & mask)); | |
7ebd796f JA |
251 | al->map[offset] |= mask; |
252 | ||
253 | if (!al->level) | |
254 | data->set_bits = nr_bits; | |
255 | ||
256 | data->nr_bits = 1; | |
257 | return al->map[offset] != -1UL; | |
258 | } | |
259 | ||
260 | static void __axmap_set(struct axmap *axmap, uint64_t bit_nr, | |
261 | struct axmap_set_data *data) | |
262 | { | |
263 | unsigned int set_bits, nr_bits = data->nr_bits; | |
264 | ||
265 | if (axmap->first_free >= bit_nr && | |
266 | axmap->first_free < bit_nr + data->nr_bits) | |
267 | axmap->first_free = -1ULL; | |
268 | ||
47d94b0b JA |
269 | if (bit_nr > axmap->nr_bits) |
270 | return; | |
271 | else if (bit_nr + nr_bits > axmap->nr_bits) | |
272 | nr_bits = axmap->nr_bits - bit_nr; | |
273 | ||
7ebd796f JA |
274 | set_bits = 0; |
275 | while (nr_bits) { | |
276 | axmap_handler(axmap, bit_nr, axmap_set_fn, data); | |
277 | set_bits += data->set_bits; | |
278 | ||
0bfdf9f1 JA |
279 | if (!data->set_bits || |
280 | data->set_bits != (BLOCKS_PER_UNIT - nr_bits)) | |
7ebd796f JA |
281 | break; |
282 | ||
283 | nr_bits -= data->set_bits; | |
284 | bit_nr += data->set_bits; | |
285 | ||
286 | data->nr_bits = nr_bits; | |
7ebd796f JA |
287 | } |
288 | ||
289 | data->set_bits = set_bits; | |
290 | } | |
291 | ||
292 | void axmap_set(struct axmap *axmap, uint64_t bit_nr) | |
293 | { | |
294 | struct axmap_set_data data = { .nr_bits = 1, }; | |
295 | ||
296 | __axmap_set(axmap, bit_nr, &data); | |
297 | } | |
298 | ||
e39c0676 JA |
299 | unsigned int axmap_set_nr(struct axmap *axmap, uint64_t bit_nr, |
300 | unsigned int nr_bits) | |
7ebd796f | 301 | { |
0bfdf9f1 JA |
302 | unsigned int set_bits = 0; |
303 | ||
304 | do { | |
09d6bf09 | 305 | struct axmap_set_data data = { .nr_bits = nr_bits, }; |
0bfdf9f1 JA |
306 | unsigned int max_bits, this_set; |
307 | ||
308 | max_bits = BLOCKS_PER_UNIT - (bit_nr & BLOCKS_PER_UNIT_MASK); | |
bd71edce | 309 | if (nr_bits > max_bits) |
0bfdf9f1 JA |
310 | data.nr_bits = max_bits; |
311 | ||
312 | this_set = data.nr_bits; | |
313 | __axmap_set(axmap, bit_nr, &data); | |
314 | set_bits += data.set_bits; | |
315 | if (data.set_bits != this_set) | |
316 | break; | |
7ebd796f | 317 | |
0bfdf9f1 JA |
318 | nr_bits -= data.set_bits; |
319 | bit_nr += data.set_bits; | |
320 | } while (nr_bits); | |
321 | ||
322 | return set_bits; | |
7ebd796f JA |
323 | } |
324 | ||
e39c0676 JA |
325 | static bool axmap_isset_fn(struct axmap_level *al, unsigned long offset, |
326 | unsigned int bit, void *unused) | |
7ebd796f JA |
327 | { |
328 | return (al->map[offset] & (1UL << bit)) != 0; | |
329 | } | |
330 | ||
e39c0676 | 331 | bool axmap_isset(struct axmap *axmap, uint64_t bit_nr) |
7ebd796f | 332 | { |
ac569176 | 333 | if (bit_nr <= axmap->nr_bits) |
c406445a | 334 | return axmap_handler_topdown(axmap, bit_nr, axmap_isset_fn); |
47d94b0b | 335 | |
e39c0676 | 336 | return false; |
7ebd796f JA |
337 | } |
338 | ||
339 | static uint64_t axmap_find_first_free(struct axmap *axmap, unsigned int level, | |
340 | uint64_t index) | |
341 | { | |
731ef4c7 | 342 | uint64_t ret = -1ULL; |
7ebd796f | 343 | unsigned long j; |
731ef4c7 | 344 | int i; |
7ebd796f JA |
345 | |
346 | /* | |
347 | * Start at the bottom, then converge towards first free bit at the top | |
348 | */ | |
349 | for (i = level; i >= 0; i--) { | |
350 | struct axmap_level *al = &axmap->levels[i]; | |
351 | ||
41264298 JA |
352 | if (index >= al->map_size) |
353 | goto err; | |
7ebd796f JA |
354 | |
355 | for (j = index; j < al->map_size; j++) { | |
356 | if (al->map[j] == -1UL) | |
357 | continue; | |
358 | ||
359 | /* | |
360 | * First free bit here is our index into the first | |
361 | * free bit at the next higher level | |
362 | */ | |
731ef4c7 | 363 | ret = index = (j << UNIT_SHIFT) + ffz(al->map[j]); |
7ebd796f JA |
364 | break; |
365 | } | |
366 | } | |
367 | ||
47d94b0b JA |
368 | if (ret < axmap->nr_bits) |
369 | return ret; | |
370 | ||
41264298 | 371 | err: |
47d94b0b | 372 | return (uint64_t) -1ULL; |
7ebd796f JA |
373 | } |
374 | ||
99b9c534 | 375 | static uint64_t axmap_first_free(struct axmap *axmap) |
7ebd796f | 376 | { |
2b2fa7f5 JA |
377 | if (!firstfree_valid(axmap)) |
378 | axmap->first_free = axmap_find_first_free(axmap, axmap->nr_levels - 1, 0); | |
7ebd796f | 379 | |
ac569176 | 380 | return axmap->first_free; |
7ebd796f JA |
381 | } |
382 | ||
383 | struct axmap_next_free_data { | |
384 | unsigned int level; | |
385 | unsigned long offset; | |
386 | uint64_t bit; | |
387 | }; | |
388 | ||
e39c0676 | 389 | static bool axmap_next_free_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
390 | unsigned int bit, void *__data) |
391 | { | |
392 | struct axmap_next_free_data *data = __data; | |
53737ae0 | 393 | uint64_t mask = ~bit_masks[(data->bit + 1) & BLOCKS_PER_UNIT_MASK]; |
7ebd796f | 394 | |
53737ae0 | 395 | if (!(mask & ~al->map[offset])) |
e39c0676 | 396 | return false; |
7ebd796f JA |
397 | |
398 | if (al->map[offset] != -1UL) { | |
399 | data->level = al->level; | |
400 | data->offset = offset; | |
e39c0676 | 401 | return true; |
7ebd796f JA |
402 | } |
403 | ||
404 | data->bit = (data->bit + BLOCKS_PER_UNIT - 1) / BLOCKS_PER_UNIT; | |
e39c0676 | 405 | return false; |
7ebd796f JA |
406 | } |
407 | ||
408 | /* | |
409 | * 'bit_nr' is already set. Find the next free bit after this one. | |
410 | */ | |
411 | uint64_t axmap_next_free(struct axmap *axmap, uint64_t bit_nr) | |
412 | { | |
413 | struct axmap_next_free_data data = { .level = -1U, .bit = bit_nr, }; | |
53737ae0 | 414 | uint64_t ret; |
7ebd796f | 415 | |
ac569176 JA |
416 | if (firstfree_valid(axmap) && bit_nr < axmap->first_free) |
417 | return axmap->first_free; | |
12bde369 | 418 | |
ac569176 JA |
419 | if (!axmap_handler(axmap, bit_nr, axmap_next_free_fn, &data)) |
420 | return axmap_first_free(axmap); | |
7ebd796f JA |
421 | |
422 | assert(data.level != -1U); | |
423 | ||
53737ae0 JA |
424 | /* |
425 | * In the rare case that the map is unaligned, we might end up | |
426 | * finding an offset that's beyond the valid end. For that case, | |
427 | * find the first free one, the map is practically full. | |
428 | */ | |
429 | ret = axmap_find_first_free(axmap, data.level, data.offset); | |
ac569176 | 430 | if (ret != -1ULL) |
53737ae0 JA |
431 | return ret; |
432 | ||
ac569176 | 433 | return axmap_first_free(axmap); |
7ebd796f | 434 | } |