ceph/src/spdk/dpdk/lib/librte_eal/include/rte_bitmap.h

   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 static inline uint64_t
 421 __rte_bitmap_line_not_empty(uint64_t *slab2)
 422 {
 423         uint64_t v1, v2, v3, v4;
 424
 425         v1 = slab2[0] | slab2[1];
 426         v2 = slab2[2] | slab2[3];
 427         v3 = slab2[4] | slab2[5];
 428         v4 = slab2[6] | slab2[7];
 429         v1 |= v2;
 430         v3 |= v4;
 431
 432         return v1 | v3;
 433 }
 434
 435 /**
 436  * Bitmap bit clear
 437  *
 438  * @param bmp
 439  *   Handle to bitmap instance
 440  * @param pos
 441  *   Bit position
 442  */
 443 static inline void
 444 rte_bitmap_clear(struct rte_bitmap *bmp, uint32_t pos)
 445 {
 446         uint64_t *slab1, *slab2;
 447         uint32_t index1, index2, offset1, offset2;
 448
 449         /* Clear bit in array2 slab */
 450         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 451         offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
 452         slab2 = bmp->array2 + index2;
 453
 454         /* Return if array2 slab is not all-zeros */
 455         *slab2 &= ~(1llu << offset2);
 456         if (*slab2){
 457                 return;
 458         }
 459
 460         /* Check the entire cache line of array2 for all-zeros */
 461         index2 &= ~ RTE_BITMAP_CL_SLAB_MASK;
 462         slab2 = bmp->array2 + index2;
 463         if (__rte_bitmap_line_not_empty(slab2)) {
 464                 return;
 465         }
 466
 467         /* The array2 cache line is all-zeros, so clear bit in array1 slab */
 468         index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
 469         offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
 470         slab1 = bmp->array1 + index1;
 471         *slab1 &= ~(1llu << offset1);
 472
 473         return;
 474 }
 475
 476 static inline int
 477 __rte_bitmap_scan_search(struct rte_bitmap *bmp)
 478 {
 479         uint64_t value1;
 480         uint32_t i;
 481
 482         /* Check current array1 slab */
 483         value1 = bmp->array1[bmp->index1];
 484         value1 &= __rte_bitmap_mask1_get(bmp);
 485
 486         if (rte_bsf64_safe(value1, &bmp->offset1))
 487                 return 1;
 488
 489         __rte_bitmap_index1_inc(bmp);
 490         bmp->offset1 = 0;
 491
 492         /* Look for another array1 slab */
 493         for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) {
 494                 value1 = bmp->array1[bmp->index1];
 495
 496                 if (rte_bsf64_safe(value1, &bmp->offset1))
 497                         return 1;
 498         }
 499
 500         return 0;
 501 }
 502
 503 static inline void
 504 __rte_bitmap_scan_read_init(struct rte_bitmap *bmp)
 505 {
 506         __rte_bitmap_index2_set(bmp);
 507         bmp->go2 = 1;
 508         rte_prefetch1((void *)(bmp->array2 + bmp->index2 + 8));
 509 }
 510
 511 static inline int
 512 __rte_bitmap_scan_read(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
 513 {
 514         uint64_t *slab2;
 515
 516         slab2 = bmp->array2 + bmp->index2;
 517         for ( ; bmp->go2 ; bmp->index2 ++, slab2 ++, bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK) {
 518                 if (*slab2) {
 519                         *pos = bmp->index2 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 520                         *slab = *slab2;
 521
 522                         bmp->index2 ++;
 523                         slab2 ++;
 524                         bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK;
 525                         return 1;
 526                 }
 527         }
 528
 529         return 0;
 530 }
 531
 532 /**
 533  * Bitmap scan (with automatic wrap-around)
 534  *
 535  * @param bmp
 536  *   Handle to bitmap instance
 537  * @param pos
 538  *   When function call returns 1, pos contains the position of the next set
 539  *   bit, otherwise not modified
 540  * @param slab
 541  *   When function call returns 1, slab contains the value of the entire 64-bit
 542  *   slab where the bit indicated by pos is located. Slabs are always 64-bit
 543  *   aligned, so the position of the first bit of the slab (this bit is not
 544  *   necessarily set) is pos / 64. Once a slab has been returned by the bitmap
 545  *   scan operation, the internal pointers of the bitmap are updated to point
 546  *   after this slab, so the same slab will not be returned again if it
 547  *   contains more than one bit which is set. When function call returns 0,
 548  *   slab is not modified.
 549  * @return
 550  *   0 if there is no bit set in the bitmap, 1 otherwise
 551  */
 552 static inline int
 553 rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
 554 {
 555         /* Return data from current array2 line if available */
 556         if (__rte_bitmap_scan_read(bmp, pos, slab)) {
 557                 return 1;
 558         }
 559
 560         /* Look for non-empty array2 line */
 561         if (__rte_bitmap_scan_search(bmp)) {
 562                 __rte_bitmap_scan_read_init(bmp);
 563                 __rte_bitmap_scan_read(bmp, pos, slab);
 564                 return 1;
 565         }
 566
 567         /* Empty bitmap */
 568         return 0;
 569 }
 570
 571 #ifdef __cplusplus
 572 }
 573 #endif
 574
 575 #endif /* __INCLUDE_RTE_BITMAP_H__ */