module/zfs/vdev_raidz_math.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (C) 2016 Gvozden Nešković. All rights reserved.
  23  */
  24
  25 #include <sys/zfs_context.h>
  26 #include <sys/types.h>
  27 #include <sys/zio.h>
  28 #include <sys/debug.h>
  29 #include <sys/zfs_debug.h>
  30
  31 #include <sys/vdev_raidz.h>
  32 #include <sys/vdev_raidz_impl.h>
  33
  34 extern boolean_t raidz_will_scalar_work(void);
  35
  36 /* Opaque implementation with NULL methods to represent original methods */
  37 static const raidz_impl_ops_t vdev_raidz_original_impl = {
  38         .name = "original",
  39         .is_supported = raidz_will_scalar_work,
  40 };
  41
  42 /* RAIDZ parity op that contain the fastest methods */
  43 static raidz_impl_ops_t vdev_raidz_fastest_impl = {
  44         .name = "fastest"
  45 };
  46
  47 /* All compiled in implementations */
  48 const raidz_impl_ops_t *raidz_all_maths[] = {
  49         &vdev_raidz_original_impl,
  50         &vdev_raidz_scalar_impl,
  51 #if defined(__x86_64) && defined(HAVE_SSE2)     /* only x86_64 for now */
  52         &vdev_raidz_sse2_impl,
  53 #endif
  54 #if defined(__x86_64) && defined(HAVE_SSSE3)    /* only x86_64 for now */
  55         &vdev_raidz_ssse3_impl,
  56 #endif
  57 #if defined(__x86_64) && defined(HAVE_AVX2)     /* only x86_64 for now */
  58         &vdev_raidz_avx2_impl,
  59 #endif
  60 #if defined(__x86_64) && defined(HAVE_AVX512F)  /* only x86_64 for now */
  61         &vdev_raidz_avx512f_impl,
  62 #endif
  63 #if defined(__x86_64) && defined(HAVE_AVX512BW) /* only x86_64 for now */
  64         &vdev_raidz_avx512bw_impl,
  65 #endif
  66 #if defined(__aarch64__)
  67         &vdev_raidz_aarch64_neon_impl,
  68         &vdev_raidz_aarch64_neonx2_impl,
  69 #endif
  70 };
  71
  72 /* Indicate that benchmark has been completed */
  73 static boolean_t raidz_math_initialized = B_FALSE;
  74
  75 /* Select raidz implementation */
  76 #define IMPL_FASTEST    (UINT32_MAX)
  77 #define IMPL_CYCLE      (UINT32_MAX - 1)
  78 #define IMPL_ORIGINAL   (0)
  79 #define IMPL_SCALAR     (1)
  80
  81 #define RAIDZ_IMPL_READ(i)      (*(volatile uint32_t *) &(i))
  82
  83 static uint32_t zfs_vdev_raidz_impl = IMPL_SCALAR;
  84 static uint32_t user_sel_impl = IMPL_FASTEST;
  85
  86 /* Hold all supported implementations */
  87 static size_t raidz_supp_impl_cnt = 0;
  88 static raidz_impl_ops_t *raidz_supp_impl[ARRAY_SIZE(raidz_all_maths)];
  89
  90 /*
  91  * kstats values for supported implementations
  92  * Values represent per disk throughput of 8 disk+parity raidz vdev [B/s]
  93  */
  94 static raidz_impl_kstat_t raidz_impl_kstats[ARRAY_SIZE(raidz_all_maths) + 1];
  95
  96 /* kstat for benchmarked implementations */
  97 static kstat_t *raidz_math_kstat = NULL;
  98
  99 /*
 100  * Selects the raidz operation for raidz_map
 101  * If rm_ops is set to NULL original raidz implementation will be used
 102  */
 103 raidz_impl_ops_t *
 104 vdev_raidz_math_get_ops()
 105 {
 106         raidz_impl_ops_t *ops = NULL;
 107         const uint32_t impl = RAIDZ_IMPL_READ(zfs_vdev_raidz_impl);
 108
 109         switch (impl) {
 110         case IMPL_FASTEST:
 111                 ASSERT(raidz_math_initialized);
 112                 ops = &vdev_raidz_fastest_impl;
 113                 break;
 114 #if !defined(_KERNEL)
 115         case IMPL_CYCLE:
 116         {
 117                 ASSERT(raidz_math_initialized);
 118                 ASSERT3U(raidz_supp_impl_cnt, >, 0);
 119                 /* Cycle through all supported implementations */
 120                 static size_t cycle_impl_idx = 0;
 121                 size_t idx = (++cycle_impl_idx) % raidz_supp_impl_cnt;
 122                 ops = raidz_supp_impl[idx];
 123         }
 124         break;
 125 #endif
 126         case IMPL_ORIGINAL:
 127                 ops = (raidz_impl_ops_t *)&vdev_raidz_original_impl;
 128                 break;
 129         case IMPL_SCALAR:
 130                 ops = (raidz_impl_ops_t *)&vdev_raidz_scalar_impl;
 131                 break;
 132         default:
 133                 ASSERT3U(impl, <, raidz_supp_impl_cnt);
 134                 ASSERT3U(raidz_supp_impl_cnt, >, 0);
 135                 ops = raidz_supp_impl[impl];
 136                 break;
 137         }
 138
 139         ASSERT3P(ops, !=, NULL);
 140
 141         return (ops);
 142 }
 143
 144 /*
 145  * Select parity generation method for raidz_map
 146  */
 147 int
 148 vdev_raidz_math_generate(raidz_map_t *rm)
 149 {
 150         raidz_gen_f gen_parity = NULL;
 151
 152         switch (raidz_parity(rm)) {
 153                 case 1:
 154                         gen_parity = rm->rm_ops->gen[RAIDZ_GEN_P];
 155                         break;
 156                 case 2:
 157                         gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQ];
 158                         break;
 159                 case 3:
 160                         gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQR];
 161                         break;
 162                 default:
 163                         gen_parity = NULL;
 164                         cmn_err(CE_PANIC, "invalid RAID-Z configuration %d",
 165                             raidz_parity(rm));
 166                         break;
 167         }
 168
 169         /* if method is NULL execute the original implementation */
 170         if (gen_parity == NULL)
 171                 return (RAIDZ_ORIGINAL_IMPL);
 172
 173         gen_parity(rm);
 174
 175         return (0);
 176 }
 177
 178 static raidz_rec_f
 179 reconstruct_fun_p_sel(raidz_map_t *rm, const int *parity_valid,
 180     const int nbaddata)
 181 {
 182         if (nbaddata == 1 && parity_valid[CODE_P]) {
 183                 return (rm->rm_ops->rec[RAIDZ_REC_P]);
 184         }
 185         return ((raidz_rec_f) NULL);
 186 }
 187
 188 static raidz_rec_f
 189 reconstruct_fun_pq_sel(raidz_map_t *rm, const int *parity_valid,
 190     const int nbaddata)
 191 {
 192         if (nbaddata == 1) {
 193                 if (parity_valid[CODE_P]) {
 194                         return (rm->rm_ops->rec[RAIDZ_REC_P]);
 195                 } else if (parity_valid[CODE_Q]) {
 196                         return (rm->rm_ops->rec[RAIDZ_REC_Q]);
 197                 }
 198         } else if (nbaddata == 2 &&
 199             parity_valid[CODE_P] && parity_valid[CODE_Q]) {
 200                 return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
 201         }
 202         return ((raidz_rec_f) NULL);
 203 }
 204
 205 static raidz_rec_f
 206 reconstruct_fun_pqr_sel(raidz_map_t *rm, const int *parity_valid,
 207     const int nbaddata)
 208 {
 209         if (nbaddata == 1) {
 210                 if (parity_valid[CODE_P]) {
 211                         return (rm->rm_ops->rec[RAIDZ_REC_P]);
 212                 } else if (parity_valid[CODE_Q]) {
 213                         return (rm->rm_ops->rec[RAIDZ_REC_Q]);
 214                 } else if (parity_valid[CODE_R]) {
 215                         return (rm->rm_ops->rec[RAIDZ_REC_R]);
 216                 }
 217         } else if (nbaddata == 2) {
 218                 if (parity_valid[CODE_P] && parity_valid[CODE_Q]) {
 219                         return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
 220                 } else if (parity_valid[CODE_P] && parity_valid[CODE_R]) {
 221                         return (rm->rm_ops->rec[RAIDZ_REC_PR]);
 222                 } else if (parity_valid[CODE_Q] && parity_valid[CODE_R]) {
 223                         return (rm->rm_ops->rec[RAIDZ_REC_QR]);
 224                 }
 225         } else if (nbaddata == 3 &&
 226             parity_valid[CODE_P] && parity_valid[CODE_Q] &&
 227             parity_valid[CODE_R]) {
 228                 return (rm->rm_ops->rec[RAIDZ_REC_PQR]);
 229         }
 230         return ((raidz_rec_f) NULL);
 231 }
 232
 233 /*
 234  * Select data reconstruction method for raidz_map
 235  * @parity_valid - Parity validity flag
 236  * @dt           - Failed data index array
 237  * @nbaddata     - Number of failed data columns
 238  */
 239 int
 240 vdev_raidz_math_reconstruct(raidz_map_t *rm, const int *parity_valid,
 241     const int *dt, const int nbaddata)
 242 {
 243         raidz_rec_f rec_fn = NULL;
 244
 245         switch (raidz_parity(rm)) {
 246         case PARITY_P:
 247                 rec_fn = reconstruct_fun_p_sel(rm, parity_valid, nbaddata);
 248                 break;
 249         case PARITY_PQ:
 250                 rec_fn = reconstruct_fun_pq_sel(rm, parity_valid, nbaddata);
 251                 break;
 252         case PARITY_PQR:
 253                 rec_fn = reconstruct_fun_pqr_sel(rm, parity_valid, nbaddata);
 254                 break;
 255         default:
 256                 cmn_err(CE_PANIC, "invalid RAID-Z configuration %d",
 257                     raidz_parity(rm));
 258                 break;
 259         }
 260
 261         if (rec_fn == NULL)
 262                 return (RAIDZ_ORIGINAL_IMPL);
 263         else
 264                 return (rec_fn(rm, dt));
 265 }
 266
 267 const char *raidz_gen_name[] = {
 268         "gen_p", "gen_pq", "gen_pqr"
 269 };
 270 const char *raidz_rec_name[] = {
 271         "rec_p", "rec_q", "rec_r",
 272         "rec_pq", "rec_pr", "rec_qr", "rec_pqr"
 273 };
 274
 275 #define RAIDZ_KSTAT_LINE_LEN    (17 + 10*12 + 1)
 276
 277 static int
 278 raidz_math_kstat_headers(char *buf, size_t size)
 279 {
 280         int i;
 281         ssize_t off;
 282
 283         ASSERT3U(size, >=, RAIDZ_KSTAT_LINE_LEN);
 284
 285         off = snprintf(buf, size, "%-17s", "implementation");
 286
 287         for (i = 0; i < ARRAY_SIZE(raidz_gen_name); i++)
 288                 off += snprintf(buf + off, size - off, "%-16s",
 289                     raidz_gen_name[i]);
 290
 291         for (i = 0; i < ARRAY_SIZE(raidz_rec_name); i++)
 292                 off += snprintf(buf + off, size - off, "%-16s",
 293                     raidz_rec_name[i]);
 294
 295         (void) snprintf(buf + off, size - off, "\n");
 296
 297         return (0);
 298 }
 299
 300 static int
 301 raidz_math_kstat_data(char *buf, size_t size, void *data)
 302 {
 303         raidz_impl_kstat_t *fstat = &raidz_impl_kstats[raidz_supp_impl_cnt];
 304         raidz_impl_kstat_t *cstat = (raidz_impl_kstat_t *)data;
 305         ssize_t off = 0;
 306         int i;
 307
 308         ASSERT3U(size, >=, RAIDZ_KSTAT_LINE_LEN);
 309
 310         if (cstat == fstat) {
 311                 off += snprintf(buf + off, size - off, "%-17s", "fastest");
 312
 313                 for (i = 0; i < ARRAY_SIZE(raidz_gen_name); i++) {
 314                         int id = fstat->gen[i];
 315                         off += snprintf(buf + off, size - off, "%-16s",
 316                             raidz_supp_impl[id]->name);
 317                 }
 318                 for (i = 0; i < ARRAY_SIZE(raidz_rec_name); i++) {
 319                         int id = fstat->rec[i];
 320                         off += snprintf(buf + off, size - off, "%-16s",
 321                             raidz_supp_impl[id]->name);
 322                 }
 323         } else {
 324                 ptrdiff_t id = cstat - raidz_impl_kstats;
 325
 326                 off += snprintf(buf + off, size - off, "%-17s",
 327                     raidz_supp_impl[id]->name);
 328
 329                 for (i = 0; i < ARRAY_SIZE(raidz_gen_name); i++)
 330                         off += snprintf(buf + off, size - off, "%-16llu",
 331                             (u_longlong_t)cstat->gen[i]);
 332
 333                 for (i = 0; i < ARRAY_SIZE(raidz_rec_name); i++)
 334                         off += snprintf(buf + off, size - off, "%-16llu",
 335                             (u_longlong_t)cstat->rec[i]);
 336         }
 337
 338         (void) snprintf(buf + off, size - off, "\n");
 339
 340         return (0);
 341 }
 342
 343 static void *
 344 raidz_math_kstat_addr(kstat_t *ksp, loff_t n)
 345 {
 346         if (n <= raidz_supp_impl_cnt)
 347                 ksp->ks_private = (void *) (raidz_impl_kstats + n);
 348         else
 349                 ksp->ks_private = NULL;
 350
 351         return (ksp->ks_private);
 352 }
 353
 354 #define BENCH_D_COLS    (8ULL)
 355 #define BENCH_COLS      (BENCH_D_COLS + PARITY_PQR)
 356 #define BENCH_ZIO_SIZE  (1ULL << SPA_OLD_MAXBLOCKSHIFT) /* 128 kiB */
 357 #define BENCH_NS        MSEC2NSEC(25)                   /* 25ms */
 358
 359 typedef void (*benchmark_fn)(raidz_map_t *rm, const int fn);
 360
 361 static void
 362 benchmark_gen_impl(raidz_map_t *rm, const int fn)
 363 {
 364         (void) fn;
 365         vdev_raidz_generate_parity(rm);
 366 }
 367
 368 static void
 369 benchmark_rec_impl(raidz_map_t *rm, const int fn)
 370 {
 371         static const int rec_tgt[7][3] = {
 372                 {1, 2, 3},      /* rec_p:   bad QR & D[0]       */
 373                 {0, 2, 3},      /* rec_q:   bad PR & D[0]       */
 374                 {0, 1, 3},      /* rec_r:   bad PQ & D[0]       */
 375                 {2, 3, 4},      /* rec_pq:  bad R  & D[0][1]    */
 376                 {1, 3, 4},      /* rec_pr:  bad Q  & D[0][1]    */
 377                 {0, 3, 4},      /* rec_qr:  bad P  & D[0][1]    */
 378                 {3, 4, 5}       /* rec_pqr: bad    & D[0][1][2] */
 379         };
 380
 381         vdev_raidz_reconstruct(rm, rec_tgt[fn], 3);
 382 }
 383
 384 /*
 385  * Benchmarking of all supported implementations (raidz_supp_impl_cnt)
 386  * is performed by setting the rm_ops pointer and calling the top level
 387  * generate/reconstruct methods of bench_rm.
 388  */
 389 static void
 390 benchmark_raidz_impl(raidz_map_t *bench_rm, const int fn, benchmark_fn bench_fn)
 391 {
 392         uint64_t run_cnt, speed, best_speed = 0;
 393         hrtime_t t_start, t_diff;
 394         raidz_impl_ops_t *curr_impl;
 395         raidz_impl_kstat_t *fstat = &raidz_impl_kstats[raidz_supp_impl_cnt];
 396         int impl, i;
 397
 398         for (impl = 0; impl < raidz_supp_impl_cnt; impl++) {
 399                 /* set an implementation to benchmark */
 400                 curr_impl = raidz_supp_impl[impl];
 401                 bench_rm->rm_ops = curr_impl;
 402
 403                 run_cnt = 0;
 404                 t_start = gethrtime();
 405
 406                 do {
 407                         for (i = 0; i < 25; i++, run_cnt++)
 408                                 bench_fn(bench_rm, fn);
 409
 410                         t_diff = gethrtime() - t_start;
 411                 } while (t_diff < BENCH_NS);
 412
 413                 speed = run_cnt * BENCH_ZIO_SIZE * NANOSEC;
 414                 speed /= (t_diff * BENCH_COLS);
 415
 416                 if (bench_fn == benchmark_gen_impl)
 417                         raidz_impl_kstats[impl].gen[fn] = speed;
 418                 else
 419                         raidz_impl_kstats[impl].rec[fn] = speed;
 420
 421                 /* Update fastest implementation method */
 422                 if (speed > best_speed) {
 423                         best_speed = speed;
 424
 425                         if (bench_fn == benchmark_gen_impl) {
 426                                 fstat->gen[fn] = impl;
 427                                 vdev_raidz_fastest_impl.gen[fn] =
 428                                     curr_impl->gen[fn];
 429                         } else {
 430                                 fstat->rec[fn] = impl;
 431                                 vdev_raidz_fastest_impl.rec[fn] =
 432                                     curr_impl->rec[fn];
 433                         }
 434                 }
 435         }
 436 }
 437
 438 void
 439 vdev_raidz_math_init(void)
 440 {
 441         raidz_impl_ops_t *curr_impl;
 442         zio_t *bench_zio = NULL;
 443         raidz_map_t *bench_rm = NULL;
 444         uint64_t bench_parity;
 445         int i, c, fn;
 446
 447         /* move supported impl into raidz_supp_impl */
 448         for (i = 0, c = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
 449                 curr_impl = (raidz_impl_ops_t *)raidz_all_maths[i];
 450
 451                 /* initialize impl */
 452                 if (curr_impl->init)
 453                         curr_impl->init();
 454
 455                 if (curr_impl->is_supported())
 456                         raidz_supp_impl[c++] = (raidz_impl_ops_t *)curr_impl;
 457         }
 458         membar_producer();              /* complete raidz_supp_impl[] init */
 459         raidz_supp_impl_cnt = c;        /* number of supported impl */
 460
 461 #if !defined(_KERNEL)
 462         /* Skip benchmarking and use last implementation as fastest */
 463         memcpy(&vdev_raidz_fastest_impl, raidz_supp_impl[raidz_supp_impl_cnt-1],
 464             sizeof (vdev_raidz_fastest_impl));
 465         strcpy(vdev_raidz_fastest_impl.name, "fastest");
 466
 467         raidz_math_initialized = B_TRUE;
 468
 469         /* Use 'cycle' math selection method for userspace */
 470         VERIFY0(vdev_raidz_impl_set("cycle"));
 471         return;
 472 #endif
 473
 474         /* Fake an zio and run the benchmark on a warmed up buffer */
 475         bench_zio = kmem_zalloc(sizeof (zio_t), KM_SLEEP);
 476         bench_zio->io_offset = 0;
 477         bench_zio->io_size = BENCH_ZIO_SIZE; /* only data columns */
 478         bench_zio->io_abd = abd_alloc_linear(BENCH_ZIO_SIZE, B_TRUE);
 479         memset(abd_to_buf(bench_zio->io_abd), 0xAA, BENCH_ZIO_SIZE);
 480
 481         /* Benchmark parity generation methods */
 482         for (fn = 0; fn < RAIDZ_GEN_NUM; fn++) {
 483                 bench_parity = fn + 1;
 484                 /* New raidz_map is needed for each generate_p/q/r */
 485                 bench_rm = vdev_raidz_map_alloc(bench_zio, SPA_MINBLOCKSHIFT,
 486                     BENCH_D_COLS + bench_parity, bench_parity);
 487
 488                 benchmark_raidz_impl(bench_rm, fn, benchmark_gen_impl);
 489
 490                 vdev_raidz_map_free(bench_rm);
 491         }
 492
 493         /* Benchmark data reconstruction methods */
 494         bench_rm = vdev_raidz_map_alloc(bench_zio, SPA_MINBLOCKSHIFT,
 495             BENCH_COLS, PARITY_PQR);
 496
 497         for (fn = 0; fn < RAIDZ_REC_NUM; fn++)
 498                 benchmark_raidz_impl(bench_rm, fn, benchmark_rec_impl);
 499
 500         vdev_raidz_map_free(bench_rm);
 501
 502         /* cleanup the bench zio */
 503         abd_free(bench_zio->io_abd);
 504         kmem_free(bench_zio, sizeof (zio_t));
 505
 506         /* install kstats for all impl */
 507         raidz_math_kstat = kstat_create("zfs", 0, "vdev_raidz_bench", "misc",
 508             KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VIRTUAL);
 509
 510         if (raidz_math_kstat != NULL) {
 511                 raidz_math_kstat->ks_data = NULL;
 512                 raidz_math_kstat->ks_ndata = UINT32_MAX;
 513                 kstat_set_raw_ops(raidz_math_kstat,
 514                     raidz_math_kstat_headers,
 515                     raidz_math_kstat_data,
 516                     raidz_math_kstat_addr);
 517                 kstat_install(raidz_math_kstat);
 518         }
 519
 520         /* Finish initialization */
 521         atomic_swap_32(&zfs_vdev_raidz_impl, user_sel_impl);
 522         raidz_math_initialized = B_TRUE;
 523 }
 524
 525 void
 526 vdev_raidz_math_fini(void)
 527 {
 528         raidz_impl_ops_t const *curr_impl;
 529         int i;
 530
 531         if (raidz_math_kstat != NULL) {
 532                 kstat_delete(raidz_math_kstat);
 533                 raidz_math_kstat = NULL;
 534         }
 535
 536         /* fini impl */
 537         for (i = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
 538                 curr_impl = raidz_all_maths[i];
 539                 if (curr_impl->fini)
 540                         curr_impl->fini();
 541         }
 542 }
 543
 544 static const struct {
 545         char *name;
 546         uint32_t sel;
 547 } math_impl_opts[] = {
 548 #if !defined(_KERNEL)
 549                 { "cycle",      IMPL_CYCLE },
 550 #endif
 551                 { "fastest",    IMPL_FASTEST },
 552                 { "original",   IMPL_ORIGINAL },
 553                 { "scalar",     IMPL_SCALAR }
 554 };
 555
 556 /*
 557  * Function sets desired raidz implementation.
 558  *
 559  * If we are called before init(), user preference will be saved in
 560  * user_sel_impl, and applied in later init() call. This occurs when module
 561  * parameter is specified on module load. Otherwise, directly update
 562  * zfs_vdev_raidz_impl.
 563  *
 564  * @val         Name of raidz implementation to use
 565  * @param       Unused.
 566  */
 567 int
 568 vdev_raidz_impl_set(const char *val)
 569 {
 570         int err = -EINVAL;
 571         char req_name[RAIDZ_IMPL_NAME_MAX];
 572         uint32_t impl = RAIDZ_IMPL_READ(user_sel_impl);
 573         size_t i;
 574
 575         /* sanitize input */
 576         i = strnlen(val, RAIDZ_IMPL_NAME_MAX);
 577         if (i == 0 || i == RAIDZ_IMPL_NAME_MAX)
 578                 return (err);
 579
 580         strlcpy(req_name, val, RAIDZ_IMPL_NAME_MAX);
 581         while (i > 0 && !!isspace(req_name[i-1]))
 582                 i--;
 583         req_name[i] = '\0';
 584
 585         /* Check mandatory options */
 586         for (i = 0; i < ARRAY_SIZE(math_impl_opts); i++) {
 587                 if (strcmp(req_name, math_impl_opts[i].name) == 0) {
 588                         impl = math_impl_opts[i].sel;
 589                         err = 0;
 590                         break;
 591                 }
 592         }
 593
 594         /* check all supported impl if init() was already called */
 595         if (err != 0 && raidz_math_initialized) {
 596                 /* check all supported implementations */
 597                 for (i = 0; i < raidz_supp_impl_cnt; i++) {
 598                         if (strcmp(req_name, raidz_supp_impl[i]->name) == 0) {
 599                                 impl = i;
 600                                 err = 0;
 601                                 break;
 602                         }
 603                 }
 604         }
 605
 606         if (err == 0) {
 607                 if (raidz_math_initialized)
 608                         atomic_swap_32(&zfs_vdev_raidz_impl, impl);
 609                 else
 610                         atomic_swap_32(&user_sel_impl, impl);
 611         }
 612
 613         return (err);
 614 }
 615
 616 #if defined(_KERNEL) && defined(HAVE_SPL)
 617 #include <linux/mod_compat.h>
 618
 619 static int
 620 zfs_vdev_raidz_impl_set(const char *val, zfs_kernel_param_t *kp)
 621 {
 622         return (vdev_raidz_impl_set(val));
 623 }
 624
 625 static int
 626 zfs_vdev_raidz_impl_get(char *buffer, zfs_kernel_param_t *kp)
 627 {
 628         int i, cnt = 0;
 629         char *fmt;
 630         const uint32_t impl = RAIDZ_IMPL_READ(zfs_vdev_raidz_impl);
 631
 632         ASSERT(raidz_math_initialized);
 633
 634         /* list mandatory options */
 635         for (i = 0; i < ARRAY_SIZE(math_impl_opts) - 2; i++) {
 636                 fmt = (impl == math_impl_opts[i].sel) ? "[%s] " : "%s ";
 637                 cnt += sprintf(buffer + cnt, fmt, math_impl_opts[i].name);
 638         }
 639
 640         /* list all supported implementations */
 641         for (i = 0; i < raidz_supp_impl_cnt; i++) {
 642                 fmt = (i == impl) ? "[%s] " : "%s ";
 643                 cnt += sprintf(buffer + cnt, fmt, raidz_supp_impl[i]->name);
 644         }
 645
 646         return (cnt);
 647 }
 648
 649 module_param_call(zfs_vdev_raidz_impl, zfs_vdev_raidz_impl_set,
 650     zfs_vdev_raidz_impl_get, NULL, 0644);
 651 MODULE_PARM_DESC(zfs_vdev_raidz_impl, "Select raidz implementation.");
 652 #endif