1 /* SPDX-License-Identifier: BSD-3-Clause 2 * Copyright(c) 2010-2014 Intel Corporation 3 */ 4 5 #ifndef __INCLUDE_RTE_BITMAP_H__ 6 #define __INCLUDE_RTE_BITMAP_H__ 7 8 #ifdef __cplusplus 9 extern "C" { 10 #endif 11 12 /** 13 * @file 14 * RTE Bitmap 15 * 16 * The bitmap component provides a mechanism to manage large arrays of bits 17 * through bit get/set/clear and bit array scan operations. 18 * 19 * The bitmap scan operation is optimized for 64-bit CPUs using 64/128 byte cache 20 * lines. The bitmap is hierarchically organized using two arrays (array1 and 21 * array2), with each bit in array1 being associated with a full cache line 22 * (512/1024 bits) of bitmap bits, which are stored in array2: the bit in array1 23 * is set only when there is at least one bit set within its associated array2 24 * bits, otherwise the bit in array1 is cleared. The read and write operations 25 * for array1 and array2 are always done in slabs of 64 bits. 26 * 27 * This bitmap is not thread safe. For lock free operation on a specific bitmap 28 * instance, a single writer thread performing bit set/clear operations is 29 * allowed, only the writer thread can do bitmap scan operations, while there 30 * can be several reader threads performing bit get operations in parallel with 31 * the writer thread. When the use of locking primitives is acceptable, the 32 * serialization of the bit set/clear and bitmap scan operations needs to be 33 * enforced by the caller, while the bit get operation does not require locking 34 * the bitmap. 35 * 36 ***/ 37 38 #include <string.h> 39 #include <rte_common.h> 40 #include <rte_config.h> 41 #include <rte_debug.h> 42 #include <rte_memory.h> 43 #include <rte_branch_prediction.h> 44 #include <rte_prefetch.h> 45 46 /* Slab */ 47 #define RTE_BITMAP_SLAB_BIT_SIZE 64 48 #define RTE_BITMAP_SLAB_BIT_SIZE_LOG2 6 49 #define RTE_BITMAP_SLAB_BIT_MASK (RTE_BITMAP_SLAB_BIT_SIZE - 1) 50 51 /* Cache line (CL) */ 52 #define RTE_BITMAP_CL_BIT_SIZE (RTE_CACHE_LINE_SIZE * 8) 53 #define RTE_BITMAP_CL_BIT_SIZE_LOG2 (RTE_CACHE_LINE_SIZE_LOG2 + 3) 54 #define RTE_BITMAP_CL_BIT_MASK (RTE_BITMAP_CL_BIT_SIZE - 1) 55 56 #define RTE_BITMAP_CL_SLAB_SIZE (RTE_BITMAP_CL_BIT_SIZE / RTE_BITMAP_SLAB_BIT_SIZE) 57 #define RTE_BITMAP_CL_SLAB_SIZE_LOG2 (RTE_BITMAP_CL_BIT_SIZE_LOG2 - RTE_BITMAP_SLAB_BIT_SIZE_LOG2) 58 #define RTE_BITMAP_CL_SLAB_MASK (RTE_BITMAP_CL_SLAB_SIZE - 1) 59 60 /** Bitmap data structure */ 61 struct rte_bitmap { 62 /* Context for array1 and array2 */ 63 uint64_t *array1; /**< Bitmap array1 */ 64 uint64_t *array2; /**< Bitmap array2 */ 65 uint32_t array1_size; /**< Number of 64-bit slabs in array1 that are actually used */ 66 uint32_t array2_size; /**< Number of 64-bit slabs in array2 */ 67 68 /* Context for the "scan next" operation */ 69 uint32_t index1; /**< Bitmap scan: Index of current array1 slab */ 70 uint32_t offset1; /**< Bitmap scan: Offset of current bit within current array1 slab */ 71 uint32_t index2; /**< Bitmap scan: Index of current array2 slab */ 72 uint32_t go2; /**< Bitmap scan: Go/stop condition for current array2 cache line */ 73 74 /* Storage space for array1 and array2 */ 75 uint8_t memory[]; 76 }; 77 78 static inline void 79 __rte_bitmap_index1_inc(struct rte_bitmap *bmp) 80 { 81 bmp->index1 = (bmp->index1 + 1) & (bmp->array1_size - 1); 82 } 83 84 static inline uint64_t 85 __rte_bitmap_mask1_get(struct rte_bitmap *bmp) 86 { 87 return (~1llu) << bmp->offset1; 88 } 89 90 static inline void 91 __rte_bitmap_index2_set(struct rte_bitmap *bmp) 92 { 93 bmp->index2 = (((bmp->index1 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2) + bmp->offset1) << RTE_BITMAP_CL_SLAB_SIZE_LOG2); 94 } 95 96 static inline uint32_t 97 __rte_bitmap_get_memory_footprint(uint32_t n_bits, 98 uint32_t *array1_byte_offset, uint32_t *array1_slabs, 99 uint32_t *array2_byte_offset, uint32_t *array2_slabs) 100 { 101 uint32_t n_slabs_context, n_slabs_array1, n_cache_lines_context_and_array1; 102 uint32_t n_cache_lines_array2; 103 uint32_t n_bytes_total; 104 105 n_cache_lines_array2 = (n_bits + RTE_BITMAP_CL_BIT_SIZE - 1) / RTE_BITMAP_CL_BIT_SIZE; 106 n_slabs_array1 = (n_cache_lines_array2 + RTE_BITMAP_SLAB_BIT_SIZE - 1) / RTE_BITMAP_SLAB_BIT_SIZE; 107 n_slabs_array1 = rte_align32pow2(n_slabs_array1); 108 n_slabs_context = (sizeof(struct rte_bitmap) + (RTE_BITMAP_SLAB_BIT_SIZE / 8) - 1) / (RTE_BITMAP_SLAB_BIT_SIZE / 8); 109 n_cache_lines_context_and_array1 = (n_slabs_context + n_slabs_array1 + RTE_BITMAP_CL_SLAB_SIZE - 1) / RTE_BITMAP_CL_SLAB_SIZE; 110 n_bytes_total = (n_cache_lines_context_and_array1 + n_cache_lines_array2) * RTE_CACHE_LINE_SIZE; 111 112 if (array1_byte_offset) { 113 *array1_byte_offset = n_slabs_context * (RTE_BITMAP_SLAB_BIT_SIZE / 8); 114 } 115 if (array1_slabs) { 116 *array1_slabs = n_slabs_array1; 117 } 118 if (array2_byte_offset) { 119 *array2_byte_offset = n_cache_lines_context_and_array1 * RTE_CACHE_LINE_SIZE; 120 } 121 if (array2_slabs) { 122 *array2_slabs = n_cache_lines_array2 * RTE_BITMAP_CL_SLAB_SIZE; 123 } 124 125 return n_bytes_total; 126 } 127 128 static inline void 129 __rte_bitmap_scan_init(struct rte_bitmap *bmp) 130 { 131 bmp->index1 = bmp->array1_size - 1; 132 bmp->offset1 = RTE_BITMAP_SLAB_BIT_SIZE - 1; 133 __rte_bitmap_index2_set(bmp); 134 bmp->index2 += RTE_BITMAP_CL_SLAB_SIZE; 135 136 bmp->go2 = 0; 137 } 138 139 /** 140 * Bitmap memory footprint calculation 141 * 142 * @param n_bits 143 * Number of bits in the bitmap 144 * @return 145 * Bitmap memory footprint measured in bytes on success, 0 on error 146 */ 147 static inline uint32_t 148 rte_bitmap_get_memory_footprint(uint32_t n_bits) { 149 /* Check input arguments */ 150 if (n_bits == 0) { 151 return 0; 152 } 153 154 return __rte_bitmap_get_memory_footprint(n_bits, NULL, NULL, NULL, NULL); 155 } 156 157 /** 158 * Bitmap initialization 159 * 160 * @param n_bits 161 * Number of pre-allocated bits in array2. 162 * @param mem 163 * Base address of array1 and array2. 164 * @param mem_size 165 * Minimum expected size of bitmap. 166 * @return 167 * Handle to bitmap instance. 168 */ 169 static inline struct rte_bitmap * 170 rte_bitmap_init(uint32_t n_bits, uint8_t *mem, uint32_t mem_size) 171 { 172 struct rte_bitmap *bmp; 173 uint32_t array1_byte_offset, array1_slabs, array2_byte_offset, array2_slabs; 174 uint32_t size; 175 176 /* Check input arguments */ 177 if (n_bits == 0) { 178 return NULL; 179 } 180 181 if ((mem == NULL) || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) { 182 return NULL; 183 } 184 185 size = __rte_bitmap_get_memory_footprint(n_bits, 186 &array1_byte_offset, &array1_slabs, 187 &array2_byte_offset, &array2_slabs); 188 if (size < mem_size) { 189 return NULL; 190 } 191 192 /* Setup bitmap */ 193 memset(mem, 0, size); 194 bmp = (struct rte_bitmap *) mem; 195 196 bmp->array1 = (uint64_t *) &mem[array1_byte_offset]; 197 bmp->array1_size = array1_slabs; 198 bmp->array2 = (uint64_t *) &mem[array2_byte_offset]; 199 bmp->array2_size = array2_slabs; 200 201 __rte_bitmap_scan_init(bmp); 202 203 return bmp; 204 } 205 206 /** 207 * @warning 208 * @b EXPERIMENTAL: this API may change without prior notice. 209 * 210 * Bitmap clear slab overhead bits. 211 * 212 * @param slabs 213 * Slab array. 214 * @param slab_size 215 * Number of 64-bit slabs in the slabs array. 216 * @param pos 217 * The start bit position in the slabs to be cleared. 218 */ 219 __rte_experimental 220 static inline void 221 __rte_bitmap_clear_slab_overhead_bits(uint64_t *slabs, uint32_t slab_size, 222 uint32_t pos) 223 { 224 uint32_t i; 225 uint32_t index = pos / RTE_BITMAP_SLAB_BIT_SIZE; 226 uint32_t offset = pos & RTE_BITMAP_SLAB_BIT_MASK; 227 228 if (offset) { 229 for (i = offset; i < RTE_BITMAP_SLAB_BIT_SIZE; i++) 230 slabs[index] &= ~(1llu << i); 231 index++; 232 } 233 if (index < slab_size) 234 memset(&slabs[index], 0, sizeof(slabs[0]) * 235 (slab_size - index)); 236 } 237 238 /** 239 * @warning 240 * @b EXPERIMENTAL: this API may change without prior notice. 241 * 242 * Bitmap initialization with all bits set 243 * 244 * @param n_bits 245 * Number of pre-allocated bits in array2. 246 * @param mem 247 * Base address of array1 and array2. 248 * @param mem_size 249 * Minimum expected size of bitmap. 250 * @return 251 * Handle to bitmap instance. 252 */ 253 __rte_experimental 254 static inline struct rte_bitmap * 255 rte_bitmap_init_with_all_set(uint32_t n_bits, uint8_t *mem, uint32_t mem_size) 256 { 257 struct rte_bitmap *bmp; 258 uint32_t array1_byte_offset, array1_slabs; 259 uint32_t array2_byte_offset, array2_slabs; 260 uint32_t size; 261 262 /* Check input arguments */ 263 if (!n_bits || !mem || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) 264 return NULL; 265 266 size = __rte_bitmap_get_memory_footprint(n_bits, 267 &array1_byte_offset, &array1_slabs, 268 &array2_byte_offset, &array2_slabs); 269 if (size < mem_size) 270 return NULL; 271 272 /* Setup bitmap */ 273 bmp = (struct rte_bitmap *) mem; 274 bmp->array1 = (uint64_t *) &mem[array1_byte_offset]; 275 bmp->array1_size = array1_slabs; 276 bmp->array2 = (uint64_t *) &mem[array2_byte_offset]; 277 bmp->array2_size = array2_slabs; 278 279 __rte_bitmap_scan_init(bmp); 280 281 memset(bmp->array1, 0xff, bmp->array1_size * sizeof(bmp->array1[0])); 282 memset(bmp->array2, 0xff, bmp->array2_size * sizeof(bmp->array2[0])); 283 /* Clear overhead bits. */ 284 __rte_bitmap_clear_slab_overhead_bits(bmp->array1, bmp->array1_size, 285 bmp->array2_size >> RTE_BITMAP_CL_SLAB_SIZE_LOG2); 286 __rte_bitmap_clear_slab_overhead_bits(bmp->array2, bmp->array2_size, 287 n_bits); 288 return bmp; 289 } 290 291 /** 292 * Bitmap free 293 * 294 * @param bmp 295 * Handle to bitmap instance 296 * @return 297 * 0 upon success, error code otherwise 298 */ 299 static inline int 300 rte_bitmap_free(struct rte_bitmap *bmp) 301 { 302 /* Check input arguments */ 303 if (bmp == NULL) { 304 return -1; 305 } 306 307 return 0; 308 } 309 310 /** 311 * Bitmap reset 312 * 313 * @param bmp 314 * Handle to bitmap instance 315 */ 316 static inline void 317 rte_bitmap_reset(struct rte_bitmap *bmp) 318 { 319 memset(bmp->array1, 0, bmp->array1_size * sizeof(uint64_t)); 320 memset(bmp->array2, 0, bmp->array2_size * sizeof(uint64_t)); 321 __rte_bitmap_scan_init(bmp); 322 } 323 324 /** 325 * Bitmap location prefetch into CPU L1 cache 326 * 327 * @param bmp 328 * Handle to bitmap instance 329 * @param pos 330 * Bit position 331 * @return 332 * 0 upon success, error code otherwise 333 */ 334 static inline void 335 rte_bitmap_prefetch0(struct rte_bitmap *bmp, uint32_t pos) 336 { 337 uint64_t *slab2; 338 uint32_t index2; 339 340 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 341 slab2 = bmp->array2 + index2; 342 rte_prefetch0((void *) slab2); 343 } 344 345 /** 346 * Bitmap bit get 347 * 348 * @param bmp 349 * Handle to bitmap instance 350 * @param pos 351 * Bit position 352 * @return 353 * 0 when bit is cleared, non-zero when bit is set 354 */ 355 static inline uint64_t 356 rte_bitmap_get(struct rte_bitmap *bmp, uint32_t pos) 357 { 358 uint64_t *slab2; 359 uint32_t index2, offset2; 360 361 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 362 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 363 slab2 = bmp->array2 + index2; 364 return (*slab2) & (1llu << offset2); 365 } 366 367 /** 368 * Bitmap bit set 369 * 370 * @param bmp 371 * Handle to bitmap instance 372 * @param pos 373 * Bit position 374 */ 375 static inline void 376 rte_bitmap_set(struct rte_bitmap *bmp, uint32_t pos) 377 { 378 uint64_t *slab1, *slab2; 379 uint32_t index1, index2, offset1, offset2; 380 381 /* Set bit in array2 slab and set bit in array1 slab */ 382 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 383 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 384 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 385 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 386 slab2 = bmp->array2 + index2; 387 slab1 = bmp->array1 + index1; 388 389 *slab2 |= 1llu << offset2; 390 *slab1 |= 1llu << offset1; 391 } 392 393 /** 394 * Bitmap slab set 395 * 396 * @param bmp 397 * Handle to bitmap instance 398 * @param pos 399 * Bit position identifying the array2 slab 400 * @param slab 401 * Value to be assigned to the 64-bit slab in array2 402 */ 403 static inline void 404 rte_bitmap_set_slab(struct rte_bitmap *bmp, uint32_t pos, uint64_t slab) 405 { 406 uint64_t *slab1, *slab2; 407 uint32_t index1, index2, offset1; 408 409 /* Set bits in array2 slab and set bit in array1 slab */ 410 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 411 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 412 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 413 slab2 = bmp->array2 + index2; 414 slab1 = bmp->array1 + index1; 415 416 *slab2 |= slab; 417 *slab1 |= 1llu << offset1; 418 } 419 420 #if RTE_BITMAP_CL_SLAB_SIZE == 8 421 static inline uint64_t 422 __rte_bitmap_line_not_empty(uint64_t *slab2) 423 { 424 uint64_t v1, v2, v3, v4; 425 426 v1 = slab2[0] | slab2[1]; 427 v2 = slab2[2] | slab2[3]; 428 v3 = slab2[4] | slab2[5]; 429 v4 = slab2[6] | slab2[7]; 430 v1 |= v2; 431 v3 |= v4; 432 433 return v1 | v3; 434 } 435 436 #elif RTE_BITMAP_CL_SLAB_SIZE == 16 437 static inline uint64_t 438 __rte_bitmap_line_not_empty(uint64_t *slab2) 439 { 440 uint64_t v1, v2, v3, v4, v5, v6, v7, v8; 441 442 v1 = slab2[0] | slab2[1]; 443 v2 = slab2[2] | slab2[3]; 444 v3 = slab2[4] | slab2[5]; 445 v4 = slab2[6] | slab2[7]; 446 v5 = slab2[8] | slab2[9]; 447 v6 = slab2[10] | slab2[11]; 448 v7 = slab2[12] | slab2[13]; 449 v8 = slab2[14] | slab2[15]; 450 v1 |= v2; 451 v3 |= v4; 452 v5 |= v6; 453 v7 |= v8; 454 455 return v1 | v3 | v5 | v7; 456 } 457 458 #endif /* RTE_BITMAP_CL_SLAB_SIZE */ 459 460 /** 461 * Bitmap bit clear 462 * 463 * @param bmp 464 * Handle to bitmap instance 465 * @param pos 466 * Bit position 467 */ 468 static inline void 469 rte_bitmap_clear(struct rte_bitmap *bmp, uint32_t pos) 470 { 471 uint64_t *slab1, *slab2; 472 uint32_t index1, index2, offset1, offset2; 473 474 /* Clear bit in array2 slab */ 475 index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 476 offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK; 477 slab2 = bmp->array2 + index2; 478 479 /* Return if array2 slab is not all-zeros */ 480 *slab2 &= ~(1llu << offset2); 481 if (*slab2){ 482 return; 483 } 484 485 /* Check the entire cache line of array2 for all-zeros */ 486 index2 &= ~ RTE_BITMAP_CL_SLAB_MASK; 487 slab2 = bmp->array2 + index2; 488 if (__rte_bitmap_line_not_empty(slab2)) { 489 return; 490 } 491 492 /* The array2 cache line is all-zeros, so clear bit in array1 slab */ 493 index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2); 494 offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK; 495 slab1 = bmp->array1 + index1; 496 *slab1 &= ~(1llu << offset1); 497 498 return; 499 } 500 501 static inline int 502 __rte_bitmap_scan_search(struct rte_bitmap *bmp) 503 { 504 uint64_t value1; 505 uint32_t i; 506 507 /* Check current array1 slab */ 508 value1 = bmp->array1[bmp->index1]; 509 value1 &= __rte_bitmap_mask1_get(bmp); 510 511 if (rte_bsf64_safe(value1, &bmp->offset1)) 512 return 1; 513 514 __rte_bitmap_index1_inc(bmp); 515 bmp->offset1 = 0; 516 517 /* Look for another array1 slab */ 518 for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) { 519 value1 = bmp->array1[bmp->index1]; 520 521 if (rte_bsf64_safe(value1, &bmp->offset1)) 522 return 1; 523 } 524 525 return 0; 526 } 527 528 static inline void 529 __rte_bitmap_scan_read_init(struct rte_bitmap *bmp) 530 { 531 __rte_bitmap_index2_set(bmp); 532 bmp->go2 = 1; 533 rte_prefetch1((void *)(bmp->array2 + bmp->index2 + 8)); 534 } 535 536 static inline int 537 __rte_bitmap_scan_read(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab) 538 { 539 uint64_t *slab2; 540 541 slab2 = bmp->array2 + bmp->index2; 542 for ( ; bmp->go2 ; bmp->index2 ++, slab2 ++, bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK) { 543 if (*slab2) { 544 *pos = bmp->index2 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2; 545 *slab = *slab2; 546 547 bmp->index2 ++; 548 slab2 ++; 549 bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK; 550 return 1; 551 } 552 } 553 554 return 0; 555 } 556 557 /** 558 * Bitmap scan (with automatic wrap-around) 559 * 560 * @param bmp 561 * Handle to bitmap instance 562 * @param pos 563 * When function call returns 1, pos contains the position of the next set 564 * bit, otherwise not modified 565 * @param slab 566 * When function call returns 1, slab contains the value of the entire 64-bit 567 * slab where the bit indicated by pos is located. Slabs are always 64-bit 568 * aligned, so the position of the first bit of the slab (this bit is not 569 * necessarily set) is pos / 64. Once a slab has been returned by the bitmap 570 * scan operation, the internal pointers of the bitmap are updated to point 571 * after this slab, so the same slab will not be returned again if it 572 * contains more than one bit which is set. When function call returns 0, 573 * slab is not modified. 574 * @return 575 * 0 if there is no bit set in the bitmap, 1 otherwise 576 */ 577 static inline int 578 rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab) 579 { 580 /* Return data from current array2 line if available */ 581 if (__rte_bitmap_scan_read(bmp, pos, slab)) { 582 return 1; 583 } 584 585 /* Look for non-empty array2 line */ 586 if (__rte_bitmap_scan_search(bmp)) { 587 __rte_bitmap_scan_read_init(bmp); 588 __rte_bitmap_scan_read(bmp, pos, slab); 589 return 1; 590 } 591 592 /* Empty bitmap */ 593 return 0; 594 } 595 596 #ifdef __cplusplus 597 } 598 #endif 599 600 #endif /* __INCLUDE_RTE_BITMAP_H__ */ 601