ceph/src/dpdk/lib/librte_sched/rte_bitmap.h

   1 /*-
   2  *   BSD LICENSE
   3  *
   4  *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
   5  *   All rights reserved.
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   7  *   Redistribution and use in source and binary forms, with or without
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  12  *       notice, this list of conditions and the following disclaimer.
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  14  *       notice, this list of conditions and the following disclaimer in
  15  *       the documentation and/or other materials provided with the
  16  *       distribution.
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  19  *       from this software without specific prior written permission.
  20  *
  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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  30  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #ifndef __INCLUDE_RTE_BITMAP_H__
  35 #define __INCLUDE_RTE_BITMAP_H__
  36
  37 #ifdef __cplusplus
  38 extern "C" {
  39 #endif
  40
  41 /**
  42  * @file
  43  * RTE Bitmap
  44  *
  45  * The bitmap component provides a mechanism to manage large arrays of bits
  46  * through bit get/set/clear and bit array scan operations.
  47  *
  48  * The bitmap scan operation is optimized for 64-bit CPUs using 64/128 byte cache
  49  * lines. The bitmap is hierarchically organized using two arrays (array1 and
  50  * array2), with each bit in array1 being associated with a full cache line
  51  * (512/1024 bits) of bitmap bits, which are stored in array2: the bit in array1
  52  * is set only when there is at least one bit set within its associated array2
  53  * bits, otherwise the bit in array1 is cleared. The read and write operations
  54  * for array1 and array2 are always done in slabs of 64 bits.
  55  *
  56  * This bitmap is not thread safe. For lock free operation on a specific bitmap
  57  * instance, a single writer thread performing bit set/clear operations is
  58  * allowed, only the writer thread can do bitmap scan operations, while there
  59  * can be several reader threads performing bit get operations in parallel with
  60  * the writer thread. When the use of locking primitives is acceptable, the
  61  * serialization of the bit set/clear and bitmap scan operations needs to be
  62  * enforced by the caller, while the bit get operation does not require locking
  63  * the bitmap.
  64  *
  65  ***/
  66
  67 #include <string.h>
  68 #include <rte_common.h>
  69 #include <rte_debug.h>
  70 #include <rte_memory.h>
  71 #include <rte_branch_prediction.h>
  72 #include <rte_prefetch.h>
  73
  74 #ifndef RTE_BITMAP_OPTIMIZATIONS
  75 #define RTE_BITMAP_OPTIMIZATIONS                         1
  76 #endif
  77
  78 /* Slab */
  79 #define RTE_BITMAP_SLAB_BIT_SIZE                 64
  80 #define RTE_BITMAP_SLAB_BIT_SIZE_LOG2            6
  81 #define RTE_BITMAP_SLAB_BIT_MASK                 (RTE_BITMAP_SLAB_BIT_SIZE - 1)
  82
  83 /* Cache line (CL) */
  84 #define RTE_BITMAP_CL_BIT_SIZE                   (RTE_CACHE_LINE_SIZE * 8)
  85 #define RTE_BITMAP_CL_BIT_SIZE_LOG2              (RTE_CACHE_LINE_SIZE_LOG2 + 3)
  86 #define RTE_BITMAP_CL_BIT_MASK                   (RTE_BITMAP_CL_BIT_SIZE - 1)
  87
  88 #define RTE_BITMAP_CL_SLAB_SIZE                  (RTE_BITMAP_CL_BIT_SIZE / RTE_BITMAP_SLAB_BIT_SIZE)
  89 #define RTE_BITMAP_CL_SLAB_SIZE_LOG2             (RTE_BITMAP_CL_BIT_SIZE_LOG2 - RTE_BITMAP_SLAB_BIT_SIZE_LOG2)
  90 #define RTE_BITMAP_CL_SLAB_MASK                  (RTE_BITMAP_CL_SLAB_SIZE - 1)
  91
  92 /** Bitmap data structure */
  93 struct rte_bitmap {
  94         /* Context for array1 and array2 */
  95         uint64_t *array1;                        /**< Bitmap array1 */
  96         uint64_t *array2;                        /**< Bitmap array2 */
  97         uint32_t array1_size;                    /**< Number of 64-bit slabs in array1 that are actually used */
  98         uint32_t array2_size;                    /**< Number of 64-bit slabs in array2 */
  99
 100         /* Context for the "scan next" operation */
 101         uint32_t index1;  /**< Bitmap scan: Index of current array1 slab */
 102         uint32_t offset1; /**< Bitmap scan: Offset of current bit within current array1 slab */
 103         uint32_t index2;  /**< Bitmap scan: Index of current array2 slab */
 104         uint32_t go2;     /**< Bitmap scan: Go/stop condition for current array2 cache line */
 105
 106         /* Storage space for array1 and array2 */
 107         uint8_t memory[];
 108 };
 109
 110 static inline void
 111 __rte_bitmap_index1_inc(struct rte_bitmap *bmp)
 112 {
 113         bmp->index1 = (bmp->index1 + 1) & (bmp->array1_size - 1);
 114 }
 115
 116 static inline uint64_t
 117 __rte_bitmap_mask1_get(struct rte_bitmap *bmp)
 118 {
 119         return (~1lu) << bmp->offset1;
 120 }
 121
 122 static inline void
 123 __rte_bitmap_index2_set(struct rte_bitmap *bmp)
 124 {
 125         bmp->index2 = (((bmp->index1 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2) + bmp->offset1) << RTE_BITMAP_CL_SLAB_SIZE_LOG2);
 126 }
 127
 128 #if RTE_BITMAP_OPTIMIZATIONS
 129
 130 static inline int
 131 rte_bsf64(uint64_t slab, uint32_t *pos)
 132 {
 133         if (likely(slab == 0)) {
 134                 return 0;
 135         }
 136
 137         *pos = __builtin_ctzll(slab);
 138         return 1;
 139 }
 140
 141 #else
 142
 143 static inline int
 144 rte_bsf64(uint64_t slab, uint32_t *pos)
 145 {
 146         uint64_t mask;
 147         uint32_t i;
 148
 149         if (likely(slab == 0)) {
 150                 return 0;
 151         }
 152
 153         for (i = 0, mask = 1; i < RTE_BITMAP_SLAB_BIT_SIZE; i ++, mask <<= 1) {
 154                 if (unlikely(slab & mask)) {
 155                         *pos = i;
 156                         return 1;
 157                 }
 158         }
 159
 160         return 0;
 161 }
 162
 163 #endif
 164
 165 static inline uint32_t
 166 __rte_bitmap_get_memory_footprint(uint32_t n_bits,
 167         uint32_t *array1_byte_offset, uint32_t *array1_slabs,
 168         uint32_t *array2_byte_offset, uint32_t *array2_slabs)
 169 {
 170         uint32_t n_slabs_context, n_slabs_array1, n_cache_lines_context_and_array1;
 171         uint32_t n_cache_lines_array2;
 172         uint32_t n_bytes_total;
 173
 174         n_cache_lines_array2 = (n_bits + RTE_BITMAP_CL_BIT_SIZE - 1) / RTE_BITMAP_CL_BIT_SIZE;
 175         n_slabs_array1 = (n_cache_lines_array2 + RTE_BITMAP_SLAB_BIT_SIZE - 1) / RTE_BITMAP_SLAB_BIT_SIZE;
 176         n_slabs_array1 = rte_align32pow2(n_slabs_array1);
 177         n_slabs_context = (sizeof(struct rte_bitmap) + (RTE_BITMAP_SLAB_BIT_SIZE / 8) - 1) / (RTE_BITMAP_SLAB_BIT_SIZE / 8);
 178         n_cache_lines_context_and_array1 = (n_slabs_context + n_slabs_array1 + RTE_BITMAP_CL_SLAB_SIZE - 1) / RTE_BITMAP_CL_SLAB_SIZE;
 179         n_bytes_total = (n_cache_lines_context_and_array1 + n_cache_lines_array2) * RTE_CACHE_LINE_SIZE;
 180
 181         if (array1_byte_offset) {
 182                 *array1_byte_offset = n_slabs_context * (RTE_BITMAP_SLAB_BIT_SIZE / 8);
 183         }
 184         if (array1_slabs) {
 185                 *array1_slabs = n_slabs_array1;
 186         }
 187         if (array2_byte_offset) {
 188                 *array2_byte_offset = n_cache_lines_context_and_array1 * RTE_CACHE_LINE_SIZE;
 189         }
 190         if (array2_slabs) {
 191                 *array2_slabs = n_cache_lines_array2 * RTE_BITMAP_CL_SLAB_SIZE;
 192         }
 193
 194         return n_bytes_total;
 195 }
 196
 197 static inline void
 198 __rte_bitmap_scan_init(struct rte_bitmap *bmp)
 199 {
 200         bmp->index1 = bmp->array1_size - 1;
 201         bmp->offset1 = RTE_BITMAP_SLAB_BIT_SIZE - 1;
 202         __rte_bitmap_index2_set(bmp);
 203         bmp->index2 += RTE_BITMAP_CL_SLAB_SIZE;
 204
 205         bmp->go2 = 0;
 206 }
 207
 208 /**
 209  * Bitmap memory footprint calculation
 210  *
 211  * @param n_bits
 212  *   Number of bits in the bitmap
 213  * @return
 214  *   Bitmap memory footprint measured in bytes on success, 0 on error
 215  */
 216 static inline uint32_t
 217 rte_bitmap_get_memory_footprint(uint32_t n_bits) {
 218         /* Check input arguments */
 219         if (n_bits == 0) {
 220                 return 0;
 221         }
 222
 223         return __rte_bitmap_get_memory_footprint(n_bits, NULL, NULL, NULL, NULL);
 224 }
 225
 226 /**
 227  * Bitmap initialization
 228  *
 229  * @param mem_size
 230  *   Minimum expected size of bitmap.
 231  * @param mem
 232  *   Base address of array1 and array2.
 233  * @param n_bits
 234  *   Number of pre-allocated bits in array2. Must be non-zero and multiple of 512.
 235  * @return
 236  *   Handle to bitmap instance.
 237  */
 238 static inline struct rte_bitmap *
 239 rte_bitmap_init(uint32_t n_bits, uint8_t *mem, uint32_t mem_size)
 240 {
 241         struct rte_bitmap *bmp;
 242         uint32_t array1_byte_offset, array1_slabs, array2_byte_offset, array2_slabs;
 243         uint32_t size;
 244
 245         /* Check input arguments */
 246         if (n_bits == 0) {
 247                 return NULL;
 248         }
 249
 250         if ((mem == NULL) || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) {
 251                 return NULL;
 252         }
 253
 254         size = __rte_bitmap_get_memory_footprint(n_bits,
 255                 &array1_byte_offset, &array1_slabs,
 256                 &array2_byte_offset, &array2_slabs);
 257         if (size < mem_size) {
 258                 return NULL;
 259         }
 260
 261         /* Setup bitmap */
 262         memset(mem, 0, size);
 263         bmp = (struct rte_bitmap *) mem;
 264
 265         bmp->array1 = (uint64_t *) &mem[array1_byte_offset];
 266         bmp->array1_size = array1_slabs;
 267         bmp->array2 = (uint64_t *) &mem[array2_byte_offset];
 268         bmp->array2_size = array2_slabs;
 269
 270         __rte_bitmap_scan_init(bmp);
 271
 272         return bmp;
 273 }
 274
 275 /**
 276  * Bitmap free
 277  *
 278  * @param bmp
 279  *   Handle to bitmap instance
 280  * @return
 281  *   0 upon success, error code otherwise
 282  */
 283 static inline int
 284 rte_bitmap_free(struct rte_bitmap *bmp)
 285 {
 286         /* Check input arguments */
 287         if (bmp == NULL) {
 288                 return -1;
 289         }
 290
 291         return 0;
 292 }
 293
 294 /**
 295  * Bitmap reset
 296  *
 297  * @param bmp
 298  *   Handle to bitmap instance
 299  */
 300 static inline void
 301 rte_bitmap_reset(struct rte_bitmap *bmp)
 302 {
 303         memset(bmp->array1, 0, bmp->array1_size * sizeof(uint64_t));
 304         memset(bmp->array2, 0, bmp->array2_size * sizeof(uint64_t));
 305         __rte_bitmap_scan_init(bmp);
 306 }
 307
 308 /**
 309  * Bitmap location prefetch into CPU L1 cache
 310  *
 311  * @param bmp
 312  *   Handle to bitmap instance
 313  * @param pos
 314  *   Bit position
 315  * @return
 316  *   0 upon success, error code otherwise
 317  */
 318 static inline void
 319 rte_bitmap_prefetch0(struct rte_bitmap *bmp, uint32_t pos)
 320 {
 321         uint64_t *slab2;
 322         uint32_t index2;
 323
 324         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 325         slab2 = bmp->array2 + index2;
 326         rte_prefetch0((void *) slab2);
 327 }
 328
 329 /**
 330  * Bitmap bit get
 331  *
 332  * @param bmp
 333  *   Handle to bitmap instance
 334  * @param pos
 335  *   Bit position
 336  * @return
 337  *   0 when bit is cleared, non-zero when bit is set
 338  */
 339 static inline uint64_t
 340 rte_bitmap_get(struct rte_bitmap *bmp, uint32_t pos)
 341 {
 342         uint64_t *slab2;
 343         uint32_t index2, offset2;
 344
 345         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 346         offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
 347         slab2 = bmp->array2 + index2;
 348         return (*slab2) & (1lu << offset2);
 349 }
 350
 351 /**
 352  * Bitmap bit set
 353  *
 354  * @param bmp
 355  *   Handle to bitmap instance
 356  * @param pos
 357  *   Bit position
 358  */
 359 static inline void
 360 rte_bitmap_set(struct rte_bitmap *bmp, uint32_t pos)
 361 {
 362         uint64_t *slab1, *slab2;
 363         uint32_t index1, index2, offset1, offset2;
 364
 365         /* Set bit in array2 slab and set bit in array1 slab */
 366         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 367         offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
 368         index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
 369         offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
 370         slab2 = bmp->array2 + index2;
 371         slab1 = bmp->array1 + index1;
 372
 373         *slab2 |= 1lu << offset2;
 374         *slab1 |= 1lu << offset1;
 375 }
 376
 377 /**
 378  * Bitmap slab set
 379  *
 380  * @param bmp
 381  *   Handle to bitmap instance
 382  * @param pos
 383  *   Bit position identifying the array2 slab
 384  * @param slab
 385  *   Value to be assigned to the 64-bit slab in array2
 386  */
 387 static inline void
 388 rte_bitmap_set_slab(struct rte_bitmap *bmp, uint32_t pos, uint64_t slab)
 389 {
 390         uint64_t *slab1, *slab2;
 391         uint32_t index1, index2, offset1;
 392
 393         /* Set bits in array2 slab and set bit in array1 slab */
 394         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 395         index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
 396         offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
 397         slab2 = bmp->array2 + index2;
 398         slab1 = bmp->array1 + index1;
 399
 400         *slab2 |= slab;
 401         *slab1 |= 1lu << offset1;
 402 }
 403
 404 static inline uint64_t
 405 __rte_bitmap_line_not_empty(uint64_t *slab2)
 406 {
 407         uint64_t v1, v2, v3, v4;
 408
 409         v1 = slab2[0] | slab2[1];
 410         v2 = slab2[2] | slab2[3];
 411         v3 = slab2[4] | slab2[5];
 412         v4 = slab2[6] | slab2[7];
 413         v1 |= v2;
 414         v3 |= v4;
 415
 416         return v1 | v3;
 417 }
 418
 419 /**
 420  * Bitmap bit clear
 421  *
 422  * @param bmp
 423  *   Handle to bitmap instance
 424  * @param pos
 425  *   Bit position
 426  */
 427 static inline void
 428 rte_bitmap_clear(struct rte_bitmap *bmp, uint32_t pos)
 429 {
 430         uint64_t *slab1, *slab2;
 431         uint32_t index1, index2, offset1, offset2;
 432
 433         /* Clear bit in array2 slab */
 434         index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 435         offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
 436         slab2 = bmp->array2 + index2;
 437
 438         /* Return if array2 slab is not all-zeros */
 439         *slab2 &= ~(1lu << offset2);
 440         if (*slab2){
 441                 return;
 442         }
 443
 444         /* Check the entire cache line of array2 for all-zeros */
 445         index2 &= ~ RTE_BITMAP_CL_SLAB_MASK;
 446         slab2 = bmp->array2 + index2;
 447         if (__rte_bitmap_line_not_empty(slab2)) {
 448                 return;
 449         }
 450
 451         /* The array2 cache line is all-zeros, so clear bit in array1 slab */
 452         index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
 453         offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
 454         slab1 = bmp->array1 + index1;
 455         *slab1 &= ~(1lu << offset1);
 456
 457         return;
 458 }
 459
 460 static inline int
 461 __rte_bitmap_scan_search(struct rte_bitmap *bmp)
 462 {
 463         uint64_t value1;
 464         uint32_t i;
 465
 466         /* Check current array1 slab */
 467         value1 = bmp->array1[bmp->index1];
 468         value1 &= __rte_bitmap_mask1_get(bmp);
 469
 470         if (rte_bsf64(value1, &bmp->offset1)) {
 471                 return 1;
 472         }
 473
 474         __rte_bitmap_index1_inc(bmp);
 475         bmp->offset1 = 0;
 476
 477         /* Look for another array1 slab */
 478         for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) {
 479                 value1 = bmp->array1[bmp->index1];
 480
 481                 if (rte_bsf64(value1, &bmp->offset1)) {
 482                         return 1;
 483                 }
 484         }
 485
 486         return 0;
 487 }
 488
 489 static inline void
 490 __rte_bitmap_scan_read_init(struct rte_bitmap *bmp)
 491 {
 492         __rte_bitmap_index2_set(bmp);
 493         bmp->go2 = 1;
 494         rte_prefetch1((void *)(bmp->array2 + bmp->index2 + 8));
 495 }
 496
 497 static inline int
 498 __rte_bitmap_scan_read(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
 499 {
 500         uint64_t *slab2;
 501
 502         slab2 = bmp->array2 + bmp->index2;
 503         for ( ; bmp->go2 ; bmp->index2 ++, slab2 ++, bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK) {
 504                 if (*slab2) {
 505                         *pos = bmp->index2 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
 506                         *slab = *slab2;
 507
 508                         bmp->index2 ++;
 509                         slab2 ++;
 510                         bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK;
 511                         return 1;
 512                 }
 513         }
 514
 515         return 0;
 516 }
 517
 518 /**
 519  * Bitmap scan (with automatic wrap-around)
 520  *
 521  * @param bmp
 522  *   Handle to bitmap instance
 523  * @param pos
 524  *   When function call returns 1, pos contains the position of the next set
 525  *   bit, otherwise not modified
 526  * @param slab
 527  *   When function call returns 1, slab contains the value of the entire 64-bit
 528  *   slab where the bit indicated by pos is located. Slabs are always 64-bit
 529  *   aligned, so the position of the first bit of the slab (this bit is not
 530  *   necessarily set) is pos / 64. Once a slab has been returned by the bitmap
 531  *   scan operation, the internal pointers of the bitmap are updated to point
 532  *   after this slab, so the same slab will not be returned again if it
 533  *   contains more than one bit which is set. When function call returns 0,
 534  *   slab is not modified.
 535  * @return
 536  *   0 if there is no bit set in the bitmap, 1 otherwise
 537  */
 538 static inline int
 539 rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
 540 {
 541         /* Return data from current array2 line if available */
 542         if (__rte_bitmap_scan_read(bmp, pos, slab)) {
 543                 return 1;
 544         }
 545
 546         /* Look for non-empty array2 line */
 547         if (__rte_bitmap_scan_search(bmp)) {
 548                 __rte_bitmap_scan_read_init(bmp);
 549                 __rte_bitmap_scan_read(bmp, pos, slab);
 550                 return 1;
 551         }
 552
 553         /* Empty bitmap */
 554         return 0;
 555 }
 556
 557 #ifdef __cplusplus
 558 }
 559 #endif
 560
 561 #endif /* __INCLUDE_RTE_BITMAP_H__ */