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 | ||
76dd186e JA |
38 | static const unsigned long bit_masks[] = { |
39 | 0x0000000000000000, 0x0000000000000001, 0x0000000000000003, 0x0000000000000007, | |
40 | 0x000000000000000f, 0x000000000000001f, 0x000000000000003f, 0x000000000000007f, | |
41 | 0x00000000000000ff, 0x00000000000001ff, 0x00000000000003ff, 0x00000000000007ff, | |
42 | 0x0000000000000fff, 0x0000000000001fff, 0x0000000000003fff, 0x0000000000007fff, | |
43 | 0x000000000000ffff, 0x000000000001ffff, 0x000000000003ffff, 0x000000000007ffff, | |
44 | 0x00000000000fffff, 0x00000000001fffff, 0x00000000003fffff, 0x00000000007fffff, | |
45 | 0x0000000000ffffff, 0x0000000001ffffff, 0x0000000003ffffff, 0x0000000007ffffff, | |
46 | 0x000000000fffffff, 0x000000001fffffff, 0x000000003fffffff, 0x000000007fffffff, | |
47 | 0x00000000ffffffff, | |
48 | #if BITS_PER_LONG == 64 | |
49 | 0x00000001ffffffff, 0x00000003ffffffff, 0x00000007ffffffff, 0x0000000fffffffff, | |
50 | 0x0000001fffffffff, 0x0000003fffffffff, 0x0000007fffffffff, 0x000000ffffffffff, | |
51 | 0x000001ffffffffff, 0x000003ffffffffff, 0x000007ffffffffff, 0x00000fffffffffff, | |
52 | 0x00001fffffffffff, 0x00003fffffffffff, 0x00007fffffffffff, 0x0000ffffffffffff, | |
53 | 0x0001ffffffffffff, 0x0003ffffffffffff, 0x0007ffffffffffff, 0x000fffffffffffff, | |
54 | 0x001fffffffffffff, 0x003fffffffffffff, 0x007fffffffffffff, 0x00ffffffffffffff, | |
55 | 0x01ffffffffffffff, 0x03ffffffffffffff, 0x07ffffffffffffff, 0x0fffffffffffffff, | |
56 | 0x1fffffffffffffff, 0x3fffffffffffffff, 0x7fffffffffffffff, 0xffffffffffffffff | |
57 | #endif | |
58 | }; | |
59 | ||
c7143018 BVA |
60 | /** |
61 | * struct axmap_level - a bitmap used to implement struct axmap | |
62 | * @level: Level index. Each map has at least one level with index zero. The | |
63 | * higher the level index, the fewer bits a struct axmap_level contains. | |
64 | * @map_size: Number of elements of the @map array. | |
65 | * @map: A bitmap with @map_size elements. | |
66 | */ | |
7ebd796f JA |
67 | struct axmap_level { |
68 | int level; | |
69 | unsigned long map_size; | |
70 | unsigned long *map; | |
71 | }; | |
72 | ||
c7143018 BVA |
73 | /** |
74 | * struct axmap - a set that can store numbers 0 .. @nr_bits - 1 | |
75 | * @nr_level: Number of elements of the @levels array. | |
76 | * @levels: struct axmap_level array in which lower levels contain more bits | |
77 | * than higher levels. | |
78 | * @nr_bits: One more than the highest value stored in the set. | |
79 | */ | |
7ebd796f JA |
80 | struct axmap { |
81 | unsigned int nr_levels; | |
82 | struct axmap_level *levels; | |
47d94b0b | 83 | uint64_t nr_bits; |
7ebd796f JA |
84 | }; |
85 | ||
c7143018 | 86 | /* Remove all elements from the @axmap set */ |
7ebd796f JA |
87 | void axmap_reset(struct axmap *axmap) |
88 | { | |
89 | int i; | |
90 | ||
91 | for (i = 0; i < axmap->nr_levels; i++) { | |
92 | struct axmap_level *al = &axmap->levels[i]; | |
93 | ||
94 | memset(al->map, 0, al->map_size * sizeof(unsigned long)); | |
95 | } | |
96 | } | |
97 | ||
98 | void axmap_free(struct axmap *axmap) | |
99 | { | |
100 | unsigned int i; | |
101 | ||
102 | if (!axmap) | |
103 | return; | |
104 | ||
105 | for (i = 0; i < axmap->nr_levels; i++) | |
aded30f7 | 106 | free(axmap->levels[i].map); |
7ebd796f | 107 | |
aded30f7 JA |
108 | free(axmap->levels); |
109 | free(axmap); | |
7ebd796f JA |
110 | } |
111 | ||
c7143018 | 112 | /* Allocate memory for a set that can store the numbers 0 .. @nr_bits - 1. */ |
7ebd796f JA |
113 | struct axmap *axmap_new(unsigned long nr_bits) |
114 | { | |
115 | struct axmap *axmap; | |
116 | unsigned int i, levels; | |
117 | ||
aded30f7 | 118 | axmap = malloc(sizeof(*axmap)); |
7ebd796f JA |
119 | if (!axmap) |
120 | return NULL; | |
121 | ||
122 | levels = 1; | |
123 | i = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
124 | while (i > 1) { | |
125 | i = (i + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
126 | levels++; | |
127 | } | |
128 | ||
129 | axmap->nr_levels = levels; | |
2404b2c3 | 130 | axmap->levels = calloc(axmap->nr_levels, sizeof(struct axmap_level)); |
70c0f356 BVA |
131 | if (!axmap->levels) |
132 | goto free_axmap; | |
47d94b0b | 133 | axmap->nr_bits = nr_bits; |
7ebd796f JA |
134 | |
135 | for (i = 0; i < axmap->nr_levels; i++) { | |
136 | struct axmap_level *al = &axmap->levels[i]; | |
137 | ||
138 | al->level = i; | |
139 | al->map_size = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
aded30f7 | 140 | al->map = malloc(al->map_size * sizeof(unsigned long)); |
7ebd796f | 141 | if (!al->map) |
70c0f356 | 142 | goto free_levels; |
7ebd796f JA |
143 | |
144 | nr_bits = (nr_bits + BLOCKS_PER_UNIT - 1) >> UNIT_SHIFT; | |
145 | } | |
146 | ||
147 | axmap_reset(axmap); | |
148 | return axmap; | |
70c0f356 BVA |
149 | |
150 | free_levels: | |
7ebd796f | 151 | for (i = 0; i < axmap->nr_levels; i++) |
70c0f356 | 152 | free(axmap->levels[i].map); |
7ebd796f | 153 | |
aded30f7 | 154 | free(axmap->levels); |
70c0f356 BVA |
155 | |
156 | free_axmap: | |
bb1116fe | 157 | free(axmap); |
7ebd796f JA |
158 | return NULL; |
159 | } | |
160 | ||
c7143018 BVA |
161 | /* |
162 | * Call @func for each level, starting at level zero, until a level is found | |
163 | * for which @func returns true. Return false if none of the @func calls | |
164 | * returns true. | |
165 | */ | |
e39c0676 JA |
166 | static bool axmap_handler(struct axmap *axmap, uint64_t bit_nr, |
167 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, | |
7ebd796f JA |
168 | void *), void *data) |
169 | { | |
170 | struct axmap_level *al; | |
edfca254 | 171 | uint64_t index = bit_nr; |
7ebd796f JA |
172 | int i; |
173 | ||
174 | for (i = 0; i < axmap->nr_levels; i++) { | |
7ebd796f JA |
175 | unsigned long offset = index >> UNIT_SHIFT; |
176 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
177 | ||
178 | al = &axmap->levels[i]; | |
179 | ||
180 | if (func(al, offset, bit, data)) | |
e39c0676 | 181 | return true; |
edfca254 JA |
182 | |
183 | if (index) | |
184 | index >>= UNIT_SHIFT; | |
7ebd796f JA |
185 | } |
186 | ||
e39c0676 | 187 | return false; |
7ebd796f JA |
188 | } |
189 | ||
c7143018 BVA |
190 | /* |
191 | * Call @func for each level, starting at the highest level, until a level is | |
192 | * found for which @func returns true. Return false if none of the @func calls | |
193 | * returns true. | |
194 | */ | |
e39c0676 | 195 | static bool axmap_handler_topdown(struct axmap *axmap, uint64_t bit_nr, |
c406445a | 196 | bool (*func)(struct axmap_level *, unsigned long, unsigned int, void *)) |
7ebd796f | 197 | { |
76dd186e | 198 | int i; |
7ebd796f JA |
199 | |
200 | for (i = axmap->nr_levels - 1; i >= 0; i--) { | |
a1a4ab81 | 201 | unsigned long index = bit_nr >> (UNIT_SHIFT * i); |
7ebd796f JA |
202 | unsigned long offset = index >> UNIT_SHIFT; |
203 | unsigned int bit = index & BLOCKS_PER_UNIT_MASK; | |
204 | ||
41264298 | 205 | if (func(&axmap->levels[i], offset, bit, NULL)) |
e39c0676 | 206 | return true; |
7ebd796f JA |
207 | } |
208 | ||
e39c0676 | 209 | return false; |
7ebd796f JA |
210 | } |
211 | ||
7ebd796f JA |
212 | struct axmap_set_data { |
213 | unsigned int nr_bits; | |
214 | unsigned int set_bits; | |
7ebd796f JA |
215 | }; |
216 | ||
c7143018 BVA |
217 | /* |
218 | * Set at most @__data->nr_bits bits in @al at offset @offset. Do not exceed | |
219 | * the boundary of the element at offset @offset. Return the number of bits | |
220 | * that have been set in @__data->set_bits if @al->level == 0. | |
221 | */ | |
e39c0676 | 222 | static bool axmap_set_fn(struct axmap_level *al, unsigned long offset, |
7ebd796f JA |
223 | unsigned int bit, void *__data) |
224 | { | |
225 | struct axmap_set_data *data = __data; | |
226 | unsigned long mask, overlap; | |
227 | unsigned int nr_bits; | |
228 | ||
229 | nr_bits = min(data->nr_bits, BLOCKS_PER_UNIT - bit); | |
230 | ||
231 | mask = bit_masks[nr_bits] << bit; | |
232 | ||
233 | /* | |
234 | * Mask off any potential overlap, only sets contig regions | |
235 | */ | |
236 | overlap = al->map[offset] & mask; | |
bd71edce | 237 | if (overlap == mask) { |
bd71edce | 238 | data->set_bits = 0; |
e39c0676 | 239 | return true; |
bd71edce | 240 | } |
7ebd796f | 241 | |
8cd5a2fd | 242 | if (overlap) { |
15a4f496 | 243 | nr_bits = ffz(~overlap) - bit; |
49e1ade1 JA |
244 | if (!nr_bits) |
245 | return true; | |
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 | ||
c7143018 | 256 | /* For the next level */ |
7ebd796f | 257 | data->nr_bits = 1; |
c7143018 | 258 | |
7ebd796f JA |
259 | return al->map[offset] != -1UL; |
260 | } | |
261 | ||
c7143018 BVA |
262 | /* |
263 | * Set up to @data->nr_bits starting from @bit_nr in @axmap. Start at | |
264 | * @bit_nr. If that bit has not yet been set then set it and continue until | |
265 | * either @data->nr_bits have been set or a 1 bit is found. Store the number | |
266 | * of bits that have been set in @data->set_bits. It is guaranteed that all | |
267 | * bits that have been requested to set fit in the same unsigned long word of | |
268 | * level 0 of @axmap. | |
269 | */ | |
7ebd796f JA |
270 | static void __axmap_set(struct axmap *axmap, uint64_t bit_nr, |
271 | struct axmap_set_data *data) | |
272 | { | |
1cf97788 | 273 | unsigned int nr_bits = data->nr_bits; |
7ebd796f | 274 | |
47d94b0b JA |
275 | if (bit_nr > axmap->nr_bits) |
276 | return; | |
277 | else if (bit_nr + nr_bits > axmap->nr_bits) | |
278 | nr_bits = axmap->nr_bits - bit_nr; | |
279 | ||
1cf97788 | 280 | assert(nr_bits <= BLOCKS_PER_UNIT); |
7ebd796f | 281 | |
1cf97788 | 282 | axmap_handler(axmap, bit_nr, axmap_set_fn, data); |
7ebd796f JA |
283 | } |
284 | ||
285 | void axmap_set(struct axmap *axmap, uint64_t bit_nr) | |
286 | { | |
287 | struct axmap_set_data data = { .nr_bits = 1, }; | |
288 | ||
289 | __axmap_set(axmap, bit_nr, &data); | |
290 | } | |
291 | ||
c7143018 BVA |
292 | /* |
293 | * Set up to @nr_bits starting from @bit in @axmap. Start at @bit. If that | |
294 | * bit has not yet been set then set it and continue until either @nr_bits | |
295 | * have been set or a 1 bit is found. Return the number of bits that have been | |
296 | * set. | |
297 | */ | |
e39c0676 JA |
298 | unsigned int axmap_set_nr(struct axmap *axmap, uint64_t bit_nr, |
299 | unsigned int nr_bits) | |
7ebd796f | 300 | { |
0bfdf9f1 JA |
301 | unsigned int set_bits = 0; |
302 | ||
303 | do { | |
09d6bf09 | 304 | struct axmap_set_data data = { .nr_bits = nr_bits, }; |
0bfdf9f1 JA |
305 | unsigned int max_bits, this_set; |
306 | ||
307 | max_bits = BLOCKS_PER_UNIT - (bit_nr & BLOCKS_PER_UNIT_MASK); | |
bd71edce | 308 | if (nr_bits > max_bits) |
0bfdf9f1 JA |
309 | data.nr_bits = max_bits; |
310 | ||
311 | this_set = data.nr_bits; | |
312 | __axmap_set(axmap, bit_nr, &data); | |
313 | set_bits += data.set_bits; | |
314 | if (data.set_bits != this_set) | |
315 | break; | |
7ebd796f | 316 | |
0bfdf9f1 JA |
317 | nr_bits -= data.set_bits; |
318 | bit_nr += data.set_bits; | |
319 | } while (nr_bits); | |
320 | ||
321 | return set_bits; | |
7ebd796f JA |
322 | } |
323 | ||
e39c0676 JA |
324 | static bool axmap_isset_fn(struct axmap_level *al, unsigned long offset, |
325 | unsigned int bit, void *unused) | |
7ebd796f JA |
326 | { |
327 | return (al->map[offset] & (1UL << bit)) != 0; | |
328 | } | |
329 | ||
e39c0676 | 330 | bool axmap_isset(struct axmap *axmap, uint64_t bit_nr) |
7ebd796f | 331 | { |
ac569176 | 332 | if (bit_nr <= axmap->nr_bits) |
c406445a | 333 | return axmap_handler_topdown(axmap, bit_nr, axmap_isset_fn); |
47d94b0b | 334 | |
e39c0676 | 335 | return false; |
7ebd796f JA |
336 | } |
337 | ||
b9304c5b MK |
338 | /* |
339 | * Find the first free bit that is at least as large as bit_nr. Return | |
340 | * -1 if no free bit is found before the end of the map. | |
341 | */ | |
342 | static uint64_t axmap_find_first_free(struct axmap *axmap, uint64_t bit_nr) | |
7ebd796f | 343 | { |
731ef4c7 | 344 | int i; |
b9304c5b MK |
345 | unsigned long temp; |
346 | unsigned int bit; | |
347 | uint64_t offset, base_index, index; | |
348 | struct axmap_level *al; | |
7ebd796f | 349 | |
b9304c5b MK |
350 | index = 0; |
351 | for (i = axmap->nr_levels - 1; i >= 0; i--) { | |
352 | al = &axmap->levels[i]; | |
7ebd796f | 353 | |
b9304c5b MK |
354 | /* Shift previously calculated index for next level */ |
355 | index <<= UNIT_SHIFT; | |
356 | ||
357 | /* | |
358 | * Start from an index that's at least as large as the | |
359 | * originally passed in bit number. | |
360 | */ | |
361 | base_index = bit_nr >> (UNIT_SHIFT * i); | |
362 | if (index < base_index) | |
363 | index = base_index; | |
364 | ||
365 | /* Get the offset and bit for this level */ | |
366 | offset = index >> UNIT_SHIFT; | |
367 | bit = index & BLOCKS_PER_UNIT_MASK; | |
368 | ||
369 | /* | |
370 | * If the previous level had unused bits in its last | |
371 | * word, the offset could be bigger than the map at | |
372 | * this level. That means no free bits exist before the | |
373 | * end of the map, so return -1. | |
374 | */ | |
375 | if (offset >= al->map_size) | |
376 | return -1ULL; | |
377 | ||
378 | /* Check the first word starting with the specific bit */ | |
379 | temp = ~bit_masks[bit] & ~al->map[offset]; | |
380 | if (temp) | |
381 | goto found; | |
382 | ||
383 | /* | |
384 | * No free bit in the first word, so iterate | |
385 | * looking for a word with one or more free bits. | |
386 | */ | |
387 | for (offset++; offset < al->map_size; offset++) { | |
388 | temp = ~al->map[offset]; | |
389 | if (temp) | |
390 | goto found; | |
7ebd796f | 391 | } |
47d94b0b | 392 | |
b9304c5b MK |
393 | /* Did not find a free bit */ |
394 | return -1ULL; | |
7ebd796f | 395 | |
b9304c5b MK |
396 | found: |
397 | /* Compute the index of the free bit just found */ | |
398 | index = (offset << UNIT_SHIFT) + ffz(~temp); | |
7ebd796f JA |
399 | } |
400 | ||
b9304c5b MK |
401 | /* If found an unused bit in the last word of level 0, return -1 */ |
402 | if (index >= axmap->nr_bits) | |
403 | return -1ULL; | |
404 | ||
405 | return index; | |
7ebd796f JA |
406 | } |
407 | ||
408 | /* | |
409 | * 'bit_nr' is already set. Find the next free bit after this one. | |
b9304c5b | 410 | * Return -1 if no free bits found. |
7ebd796f JA |
411 | */ |
412 | uint64_t axmap_next_free(struct axmap *axmap, uint64_t bit_nr) | |
413 | { | |
53737ae0 | 414 | uint64_t ret; |
b9304c5b MK |
415 | uint64_t next_bit = bit_nr + 1; |
416 | unsigned long temp; | |
417 | uint64_t offset; | |
418 | unsigned int bit; | |
7ebd796f | 419 | |
b9304c5b MK |
420 | if (bit_nr >= axmap->nr_bits) |
421 | return -1ULL; | |
12bde369 | 422 | |
b9304c5b MK |
423 | /* If at the end of the map, wrap-around */ |
424 | if (next_bit == axmap->nr_bits) | |
425 | next_bit = 0; | |
7ebd796f | 426 | |
b9304c5b MK |
427 | offset = next_bit >> UNIT_SHIFT; |
428 | bit = next_bit & BLOCKS_PER_UNIT_MASK; | |
7ebd796f | 429 | |
53737ae0 | 430 | /* |
b9304c5b MK |
431 | * As an optimization, do a quick check for a free bit |
432 | * in the current word at level 0. If not found, do | |
433 | * a topdown search. | |
53737ae0 | 434 | */ |
b9304c5b MK |
435 | temp = ~bit_masks[bit] & ~axmap->levels[0].map[offset]; |
436 | if (temp) { | |
437 | ret = (offset << UNIT_SHIFT) + ffz(~temp); | |
53737ae0 | 438 | |
b9304c5b MK |
439 | /* Might have found an unused bit at level 0 */ |
440 | if (ret >= axmap->nr_bits) | |
441 | ret = -1ULL; | |
442 | } else | |
443 | ret = axmap_find_first_free(axmap, next_bit); | |
444 | ||
445 | /* | |
446 | * If there are no free bits starting at next_bit and going | |
447 | * to the end of the map, wrap around by searching again | |
448 | * starting at bit 0. | |
449 | */ | |
450 | if (ret == -1ULL && next_bit != 0) | |
451 | ret = axmap_find_first_free(axmap, 0); | |
452 | return ret; | |
7ebd796f | 453 | } |