blktrace.c

   1 /*
   2  * blktrace support code for fio
   3  */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7 #include <errno.h>
   8
   9 #include "flist.h"
  10 #include "fio.h"
  11 #include "iolog.h"
  12 #include "blktrace.h"
  13 #include "blktrace_api.h"
  14 #include "oslib/linux-dev-lookup.h"
  15
  16 struct file_cache {
  17         unsigned int maj;
  18         unsigned int min;
  19         unsigned int fileno;
  20 };
  21
  22 /*
  23  * Just discard the pdu by seeking past it.
  24  */
  25 static int discard_pdu(FILE* f, struct blk_io_trace *t)
  26 {
  27         if (t->pdu_len == 0)
  28                 return 0;
  29
  30         dprint(FD_BLKTRACE, "discard pdu len %u\n", t->pdu_len);
  31         if (fseek(f, t->pdu_len, SEEK_CUR) < 0)
  32                 return -errno;
  33
  34         return t->pdu_len;
  35 }
  36
  37 /*
  38  * Check if this is a blktrace binary data file. We read a single trace
  39  * into memory and check for the magic signature.
  40  */
  41 bool is_blktrace(const char *filename, int *need_swap)
  42 {
  43         struct blk_io_trace t;
  44         int fd, ret;
  45
  46         fd = open(filename, O_RDONLY);
  47         if (fd < 0)
  48                 return false;
  49
  50         ret = read(fd, &t, sizeof(t));
  51         close(fd);
  52
  53         if (ret < 0) {
  54                 perror("read blktrace");
  55                 return false;
  56         } else if (ret != sizeof(t)) {
  57                 log_err("fio: short read on blktrace file\n");
  58                 return false;
  59         }
  60
  61         if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
  62                 *need_swap = 0;
  63                 return true;
  64         }
  65
  66         /*
  67          * Maybe it needs to be endian swapped...
  68          */
  69         t.magic = fio_swap32(t.magic);
  70         if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
  71                 *need_swap = 1;
  72                 return true;
  73         }
  74
  75         return false;
  76 }
  77
  78 #define FMINORBITS      20
  79 #define FMINORMASK      ((1U << FMINORBITS) - 1)
  80 #define FMAJOR(dev)     ((unsigned int) ((dev) >> FMINORBITS))
  81 #define FMINOR(dev)     ((unsigned int) ((dev) & FMINORMASK))
  82
  83 static void trace_add_open_close_event(struct thread_data *td, int fileno, enum file_log_act action)
  84 {
  85         struct io_piece *ipo;
  86
  87         ipo = calloc(1, sizeof(*ipo));
  88         init_ipo(ipo);
  89
  90         ipo->ddir = DDIR_INVAL;
  91         ipo->fileno = fileno;
  92         ipo->file_action = action;
  93         flist_add_tail(&ipo->list, &td->io_log_list);
  94 }
  95
  96 static int trace_add_file(struct thread_data *td, __u32 device,
  97                           struct file_cache *cache)
  98 {
  99         unsigned int maj = FMAJOR(device);
 100         unsigned int min = FMINOR(device);
 101         struct fio_file *f;
 102         char dev[256];
 103         unsigned int i;
 104
 105         if (cache->maj == maj && cache->min == min)
 106                 return cache->fileno;
 107
 108         cache->maj = maj;
 109         cache->min = min;
 110
 111         /*
 112          * check for this file in our list
 113          */
 114         for_each_file(td, f, i)
 115                 if (f->major == maj && f->minor == min) {
 116                         cache->fileno = f->fileno;
 117                         return cache->fileno;
 118                 }
 119
 120         strcpy(dev, "/dev");
 121         if (blktrace_lookup_device(td->o.replay_redirect, dev, maj, min)) {
 122                 int fileno;
 123
 124                 if (td->o.replay_redirect)
 125                         dprint(FD_BLKTRACE, "device lookup: %d/%d\n overridden"
 126                                         " with: %s\n", maj, min,
 127                                         td->o.replay_redirect);
 128                 else
 129                         dprint(FD_BLKTRACE, "device lookup: %d/%d\n", maj, min);
 130
 131                 dprint(FD_BLKTRACE, "add devices %s\n", dev);
 132                 fileno = add_file_exclusive(td, dev);
 133                 td->o.open_files++;
 134                 td->files[fileno]->major = maj;
 135                 td->files[fileno]->minor = min;
 136                 trace_add_open_close_event(td, fileno, FIO_LOG_OPEN_FILE);
 137                 cache->fileno = fileno;
 138         }
 139
 140         return cache->fileno;
 141 }
 142
 143 static void t_bytes_align(struct thread_options *o, struct blk_io_trace *t)
 144 {
 145         if (!o->replay_align)
 146                 return;
 147
 148         t->bytes = (t->bytes + o->replay_align - 1) & ~(o->replay_align - 1);
 149 }
 150
 151 /*
 152  * Store blk_io_trace data in an ipo for later retrieval.
 153  */
 154 static void store_ipo(struct thread_data *td, unsigned long long offset,
 155                       unsigned int bytes, int rw, unsigned long long ttime,
 156                       int fileno)
 157 {
 158         struct io_piece *ipo;
 159
 160         ipo = calloc(1, sizeof(*ipo));
 161         init_ipo(ipo);
 162
 163         ipo->offset = offset * 512;
 164         if (td->o.replay_scale)
 165                 ipo->offset = ipo->offset / td->o.replay_scale;
 166         ipo_bytes_align(td->o.replay_align, ipo);
 167         ipo->len = bytes;
 168         ipo->delay = ttime / 1000;
 169         if (rw)
 170                 ipo->ddir = DDIR_WRITE;
 171         else
 172                 ipo->ddir = DDIR_READ;
 173         ipo->fileno = fileno;
 174
 175         dprint(FD_BLKTRACE, "store ddir=%d, off=%llu, len=%lu, delay=%lu\n",
 176                                                         ipo->ddir, ipo->offset,
 177                                                         ipo->len, ipo->delay);
 178         queue_io_piece(td, ipo);
 179 }
 180
 181 static bool handle_trace_notify(struct blk_io_trace *t)
 182 {
 183         switch (t->action) {
 184         case BLK_TN_PROCESS:
 185                 dprint(FD_BLKTRACE, "got process notify: %x, %d\n",
 186                                 t->action, t->pid);
 187                 break;
 188         case BLK_TN_TIMESTAMP:
 189                 dprint(FD_BLKTRACE, "got timestamp notify: %x, %d\n",
 190                                 t->action, t->pid);
 191                 break;
 192         case BLK_TN_MESSAGE:
 193                 break;
 194         default:
 195                 dprint(FD_BLKTRACE, "unknown trace act %x\n", t->action);
 196                 break;
 197         }
 198         return false;
 199 }
 200
 201 static bool handle_trace_discard(struct thread_data *td,
 202                                  struct blk_io_trace *t,
 203                                  unsigned long long ttime,
 204                                  unsigned long *ios, unsigned long long *bs,
 205                                  struct file_cache *cache)
 206 {
 207         struct io_piece *ipo;
 208         int fileno;
 209
 210         if (td->o.replay_skip & (1u << DDIR_TRIM))
 211                 return false;
 212
 213         ipo = calloc(1, sizeof(*ipo));
 214         init_ipo(ipo);
 215         fileno = trace_add_file(td, t->device, cache);
 216
 217         ios[DDIR_TRIM]++;
 218         if (t->bytes > bs[DDIR_TRIM])
 219                 bs[DDIR_TRIM] = t->bytes;
 220
 221         td->o.size += t->bytes;
 222
 223         INIT_FLIST_HEAD(&ipo->list);
 224
 225         ipo->offset = t->sector * 512;
 226         if (td->o.replay_scale)
 227                 ipo->offset = ipo->offset / td->o.replay_scale;
 228         ipo_bytes_align(td->o.replay_align, ipo);
 229         ipo->len = t->bytes;
 230         ipo->delay = ttime / 1000;
 231         ipo->ddir = DDIR_TRIM;
 232         ipo->fileno = fileno;
 233
 234         dprint(FD_BLKTRACE, "store discard, off=%llu, len=%lu, delay=%lu\n",
 235                                                         ipo->offset, ipo->len,
 236                                                         ipo->delay);
 237         queue_io_piece(td, ipo);
 238         return true;
 239 }
 240
 241 static void dump_trace(struct blk_io_trace *t)
 242 {
 243         log_err("blktrace: ignoring zero byte trace: action=%x\n", t->action);
 244 }
 245
 246 static bool handle_trace_fs(struct thread_data *td, struct blk_io_trace *t,
 247                             unsigned long long ttime, unsigned long *ios,
 248                             unsigned long long *bs, struct file_cache *cache)
 249 {
 250         int rw;
 251         int fileno;
 252
 253         fileno = trace_add_file(td, t->device, cache);
 254
 255         rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
 256
 257         if (rw) {
 258                 if (td->o.replay_skip & (1u << DDIR_WRITE))
 259                         return false;
 260         } else {
 261                 if (td->o.replay_skip & (1u << DDIR_READ))
 262                         return false;
 263         }
 264
 265         if (!t->bytes) {
 266                 if (!fio_did_warn(FIO_WARN_BTRACE_ZERO))
 267                         dump_trace(t);
 268                 return false;
 269         }
 270
 271         if (t->bytes > bs[rw])
 272                 bs[rw] = t->bytes;
 273
 274         ios[rw]++;
 275         td->o.size += t->bytes;
 276         store_ipo(td, t->sector, t->bytes, rw, ttime, fileno);
 277         return true;
 278 }
 279
 280 static bool handle_trace_flush(struct thread_data *td, struct blk_io_trace *t,
 281                                unsigned long long ttime, unsigned long *ios,
 282                                struct file_cache *cache)
 283 {
 284         struct io_piece *ipo;
 285         int fileno;
 286
 287         if (td->o.replay_skip & (1u << DDIR_SYNC))
 288                 return false;
 289
 290         ipo = calloc(1, sizeof(*ipo));
 291         init_ipo(ipo);
 292         fileno = trace_add_file(td, t->device, cache);
 293
 294         ipo->delay = ttime / 1000;
 295         ipo->ddir = DDIR_SYNC;
 296         ipo->fileno = fileno;
 297
 298         ios[DDIR_SYNC]++;
 299         dprint(FD_BLKTRACE, "store flush delay=%lu\n", ipo->delay);
 300
 301         if (!(td->flags & TD_F_SYNCS))
 302                 td->flags |= TD_F_SYNCS;
 303
 304         queue_io_piece(td, ipo);
 305         return true;
 306 }
 307
 308 /*
 309  * We only care for queue traces, most of the others are side effects
 310  * due to internal workings of the block layer.
 311  */
 312 static bool queue_trace(struct thread_data *td, struct blk_io_trace *t,
 313                          unsigned long *ios, unsigned long long *bs,
 314                          struct file_cache *cache)
 315 {
 316         unsigned long long *last_ttime = &td->io_log_last_ttime;
 317         unsigned long long delay = 0;
 318
 319         if ((t->action & 0xffff) != __BLK_TA_QUEUE)
 320                 return false;
 321
 322         if (!(t->action & BLK_TC_ACT(BLK_TC_NOTIFY))) {
 323                 delay = delay_since_ttime(td, t->time);
 324                 *last_ttime = t->time;
 325         }
 326
 327         t_bytes_align(&td->o, t);
 328
 329         if (t->action & BLK_TC_ACT(BLK_TC_NOTIFY))
 330                 return handle_trace_notify(t);
 331         else if (t->action & BLK_TC_ACT(BLK_TC_DISCARD))
 332                 return handle_trace_discard(td, t, delay, ios, bs, cache);
 333         else if (t->action & BLK_TC_ACT(BLK_TC_FLUSH))
 334                 return handle_trace_flush(td, t, delay, ios, cache);
 335         else
 336                 return handle_trace_fs(td, t, delay, ios, bs, cache);
 337 }
 338
 339 static void byteswap_trace(struct blk_io_trace *t)
 340 {
 341         t->magic = fio_swap32(t->magic);
 342         t->sequence = fio_swap32(t->sequence);
 343         t->time = fio_swap64(t->time);
 344         t->sector = fio_swap64(t->sector);
 345         t->bytes = fio_swap32(t->bytes);
 346         t->action = fio_swap32(t->action);
 347         t->pid = fio_swap32(t->pid);
 348         t->device = fio_swap32(t->device);
 349         t->cpu = fio_swap32(t->cpu);
 350         t->error = fio_swap16(t->error);
 351         t->pdu_len = fio_swap16(t->pdu_len);
 352 }
 353
 354 static bool t_is_write(struct blk_io_trace *t)
 355 {
 356         return (t->action & BLK_TC_ACT(BLK_TC_WRITE | BLK_TC_DISCARD)) != 0;
 357 }
 358
 359 static enum fio_ddir t_get_ddir(struct blk_io_trace *t)
 360 {
 361         if (t->action & BLK_TC_ACT(BLK_TC_READ))
 362                 return DDIR_READ;
 363         else if (t->action & BLK_TC_ACT(BLK_TC_WRITE))
 364                 return DDIR_WRITE;
 365         else if (t->action & BLK_TC_ACT(BLK_TC_DISCARD))
 366                 return DDIR_TRIM;
 367
 368         return DDIR_INVAL;
 369 }
 370
 371 static void depth_inc(struct blk_io_trace *t, int *depth)
 372 {
 373         enum fio_ddir ddir;
 374
 375         ddir = t_get_ddir(t);
 376         if (ddir != DDIR_INVAL)
 377                 depth[ddir]++;
 378 }
 379
 380 static void depth_dec(struct blk_io_trace *t, int *depth)
 381 {
 382         enum fio_ddir ddir;
 383
 384         ddir = t_get_ddir(t);
 385         if (ddir != DDIR_INVAL)
 386                 depth[ddir]--;
 387 }
 388
 389 static void depth_end(struct blk_io_trace *t, int *this_depth, int *depth)
 390 {
 391         enum fio_ddir ddir = DDIR_INVAL;
 392
 393         ddir = t_get_ddir(t);
 394         if (ddir != DDIR_INVAL) {
 395                 depth[ddir] = max(depth[ddir], this_depth[ddir]);
 396                 this_depth[ddir] = 0;
 397         }
 398 }
 399
 400 /*
 401  * Load a blktrace file by reading all the blk_io_trace entries, and storing
 402  * them as io_pieces like the fio text version would do.
 403  */
 404 bool init_blktrace_read(struct thread_data *td, const char *filename, int need_swap)
 405 {
 406         int old_state;
 407
 408         td->io_log_rfile = fopen(filename, "rb");
 409         if (!td->io_log_rfile) {
 410                 td_verror(td, errno, "open blktrace file");
 411                 goto err;
 412         }
 413         td->io_log_blktrace_swap = need_swap;
 414         td->io_log_last_ttime = 0;
 415         td->o.size = 0;
 416
 417         free_release_files(td);
 418
 419         old_state = td_bump_runstate(td, TD_SETTING_UP);
 420
 421         if (!read_blktrace(td)) {
 422                 goto err;
 423         }
 424
 425         td_restore_runstate(td, old_state);
 426
 427         if (!td->files_index) {
 428                 log_err("fio: did not find replay device(s)\n");
 429                 return false;
 430         }
 431
 432         return true;
 433
 434 err:
 435         if (td->io_log_rfile) {
 436                 fclose(td->io_log_rfile);
 437                 td->io_log_rfile = NULL;
 438         }
 439         return false;
 440 }
 441
 442 bool read_blktrace(struct thread_data* td)
 443 {
 444         struct blk_io_trace t;
 445         struct file_cache cache = {
 446                 .maj = ~0U,
 447                 .min = ~0U,
 448         };
 449         unsigned long ios[DDIR_RWDIR_SYNC_CNT] = { };
 450         unsigned long long rw_bs[DDIR_RWDIR_CNT] = { };
 451         unsigned long skipped_writes;
 452         FILE *f = td->io_log_rfile;
 453         int i, max_depth;
 454         struct fio_file *fiof;
 455         int this_depth[DDIR_RWDIR_CNT] = { };
 456         int depth[DDIR_RWDIR_CNT] = { };
 457         int64_t items_to_fetch = 0;
 458
 459         if (td->o.read_iolog_chunked) {
 460                 items_to_fetch = iolog_items_to_fetch(td);
 461                 if (!items_to_fetch)
 462                         return true;
 463         }
 464
 465         skipped_writes = 0;
 466         do {
 467                 int ret = fread(&t, 1, sizeof(t), f);
 468
 469                 if (ferror(f)) {
 470                         td_verror(td, errno, "read blktrace file");
 471                         goto err;
 472                 } else if (feof(f)) {
 473                         break;
 474                 } else if (ret < (int) sizeof(t)) {
 475                         log_err("fio: iolog short read\n");
 476                         break;
 477                 }
 478
 479                 if (td->io_log_blktrace_swap)
 480                         byteswap_trace(&t);
 481
 482                 if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
 483                         log_err("fio: bad magic in blktrace data: %x\n",
 484                                                                 t.magic);
 485                         goto err;
 486                 }
 487                 if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
 488                         log_err("fio: bad blktrace version %d\n",
 489                                                                 t.magic & 0xff);
 490                         goto err;
 491                 }
 492                 ret = discard_pdu(f, &t);
 493                 if (ret < 0) {
 494                         td_verror(td, -ret, "blktrace lseek");
 495                         goto err;
 496                 }
 497                 if ((t.action & BLK_TC_ACT(BLK_TC_NOTIFY)) == 0) {
 498                         if ((t.action & 0xffff) == __BLK_TA_QUEUE)
 499                                 depth_inc(&t, this_depth);
 500                         else if (((t.action & 0xffff) == __BLK_TA_BACKMERGE) ||
 501                                 ((t.action & 0xffff) == __BLK_TA_FRONTMERGE))
 502                                 depth_dec(&t, this_depth);
 503                         else if ((t.action & 0xffff) == __BLK_TA_COMPLETE)
 504                                 depth_end(&t, this_depth, depth);
 505
 506                         if (t_is_write(&t) && read_only) {
 507                                 skipped_writes++;
 508                                 continue;
 509                         }
 510                 }
 511
 512                 if (!queue_trace(td, &t, ios, rw_bs, &cache))
 513                         continue;
 514
 515                 if (td->o.read_iolog_chunked) {
 516                         td->io_log_current++;
 517                         items_to_fetch--;
 518                         if (items_to_fetch == 0)
 519                                 break;
 520                 }
 521         } while (1);
 522
 523         if (td->o.read_iolog_chunked) {
 524                 td->io_log_highmark = td->io_log_current;
 525                 td->io_log_checkmark = (td->io_log_highmark + 1) / 2;
 526                 fio_gettime(&td->io_log_highmark_time, NULL);
 527         }
 528
 529         if (skipped_writes)
 530                 log_err("fio: %s skips replay of %lu writes due to read-only\n",
 531                                                 td->o.name, skipped_writes);
 532
 533         if (td->o.read_iolog_chunked) {
 534                 if (td->io_log_current == 0) {
 535                         return false;
 536                 }
 537                 td->o.td_ddir = TD_DDIR_RW;
 538                 if ((rw_bs[DDIR_READ] > td->o.max_bs[DDIR_READ] ||
 539                      rw_bs[DDIR_WRITE] > td->o.max_bs[DDIR_WRITE] ||
 540                      rw_bs[DDIR_TRIM] > td->o.max_bs[DDIR_TRIM]) &&
 541                     td->orig_buffer)
 542                 {
 543                         td->o.max_bs[DDIR_READ] = max(td->o.max_bs[DDIR_READ], rw_bs[DDIR_READ]);
 544                         td->o.max_bs[DDIR_WRITE] = max(td->o.max_bs[DDIR_WRITE], rw_bs[DDIR_WRITE]);
 545                         td->o.max_bs[DDIR_TRIM] = max(td->o.max_bs[DDIR_TRIM], rw_bs[DDIR_TRIM]);
 546                         io_u_quiesce(td);
 547                         free_io_mem(td);
 548                         init_io_u_buffers(td);
 549                 }
 550                 return true;
 551         }
 552
 553         for_each_file(td, fiof, i)
 554                 trace_add_open_close_event(td, fiof->fileno, FIO_LOG_CLOSE_FILE);
 555
 556         fclose(td->io_log_rfile);
 557         td->io_log_rfile = NULL;
 558
 559         /*
 560          * For stacked devices, we don't always get a COMPLETE event so
 561          * the depth grows to insane values. Limit it to something sane(r).
 562          */
 563         max_depth = 0;
 564         for (i = 0; i < DDIR_RWDIR_CNT; i++) {
 565                 if (depth[i] > 1024)
 566                         depth[i] = 1024;
 567                 else if (!depth[i] && ios[i])
 568                         depth[i] = 1;
 569                 max_depth = max(depth[i], max_depth);
 570         }
 571
 572         if (!ios[DDIR_READ] && !ios[DDIR_WRITE] && !ios[DDIR_TRIM] &&
 573             !ios[DDIR_SYNC]) {
 574                 log_err("fio: found no ios in blktrace data\n");
 575                 return false;
 576         }
 577
 578         td->o.td_ddir = 0;
 579         if (ios[DDIR_READ]) {
 580                 td->o.td_ddir |= TD_DDIR_READ;
 581                 td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
 582         }
 583         if (ios[DDIR_WRITE]) {
 584                 td->o.td_ddir |= TD_DDIR_WRITE;
 585                 td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
 586         }
 587         if (ios[DDIR_TRIM]) {
 588                 td->o.td_ddir |= TD_DDIR_TRIM;
 589                 td->o.max_bs[DDIR_TRIM] = rw_bs[DDIR_TRIM];
 590         }
 591
 592         /*
 593          * If depth wasn't manually set, use probed depth
 594          */
 595         if (!fio_option_is_set(&td->o, iodepth))
 596                 td->o.iodepth = td->o.iodepth_low = max_depth;
 597
 598         return true;
 599 err:
 600         fclose(f);
 601         return false;
 602 }
 603
 604 static int init_merge_param_list(fio_fp64_t *vals, struct blktrace_cursor *bcs,
 605                                  int nr_logs, int def, size_t off)
 606 {
 607         int i = 0, len = 0;
 608
 609         while (len < FIO_IO_U_LIST_MAX_LEN && vals[len].u.f != 0.0)
 610                 len++;
 611
 612         if (len && len != nr_logs)
 613                 return len;
 614
 615         for (i = 0; i < nr_logs; i++) {
 616                 int *val = (int *)((char *)&bcs[i] + off);
 617                 *val = def;
 618                 if (len)
 619                         *val = (int)vals[i].u.f;
 620         }
 621
 622         return 0;
 623
 624 }
 625
 626 static int find_earliest_io(struct blktrace_cursor *bcs, int nr_logs)
 627 {
 628         __u64 time = ~(__u64)0;
 629         int idx = 0, i;
 630
 631         for (i = 0; i < nr_logs; i++) {
 632                 if (bcs[i].t.time < time) {
 633                         time = bcs[i].t.time;
 634                         idx = i;
 635                 }
 636         }
 637
 638         return idx;
 639 }
 640
 641 static void merge_finish_file(struct blktrace_cursor *bcs, int i, int *nr_logs)
 642 {
 643         bcs[i].iter++;
 644         if (bcs[i].iter < bcs[i].nr_iter) {
 645                 fseek(bcs[i].f, 0, SEEK_SET);
 646                 return;
 647         }
 648
 649         *nr_logs -= 1;
 650
 651         /* close file */
 652         fclose(bcs[i].f);
 653
 654         /* keep active files contiguous */
 655         memmove(&bcs[i], &bcs[*nr_logs], sizeof(bcs[i]));
 656 }
 657
 658 static int read_trace(struct thread_data *td, struct blktrace_cursor *bc)
 659 {
 660         int ret = 0;
 661         struct blk_io_trace *t = &bc->t;
 662
 663 read_skip:
 664         /* read an io trace */
 665         ret = fread(&t, 1, sizeof(t), bc->f);
 666         if (ferror(bc->f)) {
 667                 td_verror(td, errno, "read blktrace file");
 668                 return ret;
 669         } else if (feof(bc->f)) {
 670                 if (!bc->length)
 671                         bc->length = bc->t.time;
 672                 return ret;
 673         } else if (ret < (int) sizeof(*t)) {
 674                 log_err("fio: iolog short read\n");
 675                 return -1;
 676         }
 677
 678         if (bc->swap)
 679                 byteswap_trace(t);
 680
 681         /* skip over actions that fio does not care about */
 682         if ((t->action & 0xffff) != __BLK_TA_QUEUE ||
 683             t_get_ddir(t) == DDIR_INVAL) {
 684                 ret = discard_pdu(bc->f, t);
 685                 if (ret < 0) {
 686                         td_verror(td, -ret, "blktrace lseek");
 687                         return ret;
 688                 }
 689                 goto read_skip;
 690         }
 691
 692         t->time = (t->time + bc->iter * bc->length) * bc->scalar / 100;
 693
 694         return ret;
 695 }
 696
 697 static int write_trace(FILE *fp, struct blk_io_trace *t)
 698 {
 699         /* pdu is not used so just write out only the io trace */
 700         t->pdu_len = 0;
 701         return fwrite((void *)t, sizeof(*t), 1, fp);
 702 }
 703
 704 int merge_blktrace_iologs(struct thread_data *td)
 705 {
 706         int nr_logs = get_max_str_idx(td->o.read_iolog_file);
 707         struct blktrace_cursor *bcs = malloc(sizeof(struct blktrace_cursor) *
 708                                              nr_logs);
 709         struct blktrace_cursor *bc;
 710         FILE *merge_fp;
 711         char *str, *ptr, *name, *merge_buf;
 712         int i, ret;
 713
 714         ret = init_merge_param_list(td->o.merge_blktrace_scalars, bcs, nr_logs,
 715                                     100, offsetof(struct blktrace_cursor,
 716                                                   scalar));
 717         if (ret) {
 718                 log_err("fio: merge_blktrace_scalars(%d) != nr_logs(%d)\n",
 719                         ret, nr_logs);
 720                 goto err_param;
 721         }
 722
 723         ret = init_merge_param_list(td->o.merge_blktrace_iters, bcs, nr_logs,
 724                                     1, offsetof(struct blktrace_cursor,
 725                                                 nr_iter));
 726         if (ret) {
 727                 log_err("fio: merge_blktrace_iters(%d) != nr_logs(%d)\n",
 728                         ret, nr_logs);
 729                 goto err_param;
 730         }
 731
 732         /* setup output file */
 733         merge_fp = fopen(td->o.merge_blktrace_file, "w");
 734         merge_buf = malloc(128 * 1024);
 735         if (!merge_buf)
 736                 goto err_out_file;
 737         ret = setvbuf(merge_fp, merge_buf, _IOFBF, 128 * 1024);
 738         if (ret)
 739                 goto err_merge_buf;
 740
 741         /* setup input files */
 742         str = ptr = strdup(td->o.read_iolog_file);
 743         nr_logs = 0;
 744         for (i = 0; (name = get_next_str(&ptr)) != NULL; i++) {
 745                 bcs[i].f = fopen(name, "rb");
 746                 if (!bcs[i].f) {
 747                         log_err("fio: could not open file: %s\n", name);
 748                         ret = -errno;
 749                         free(str);
 750                         goto err_file;
 751                 }
 752                 nr_logs++;
 753
 754                 if (!is_blktrace(name, &bcs[i].swap)) {
 755                         log_err("fio: file is not a blktrace: %s\n", name);
 756                         free(str);
 757                         goto err_file;
 758                 }
 759
 760                 ret = read_trace(td, &bcs[i]);
 761                 if (ret < 0) {
 762                         free(str);
 763                         goto err_file;
 764                 } else if (!ret) {
 765                         merge_finish_file(bcs, i, &nr_logs);
 766                         i--;
 767                 }
 768         }
 769         free(str);
 770
 771         /* merge files */
 772         while (nr_logs) {
 773                 i = find_earliest_io(bcs, nr_logs);
 774                 bc = &bcs[i];
 775                 /* skip over the pdu */
 776                 ret = discard_pdu(bc->f, &bc->t);
 777                 if (ret < 0) {
 778                         td_verror(td, -ret, "blktrace lseek");
 779                         goto err_file;
 780                 }
 781
 782                 ret = write_trace(merge_fp, &bc->t);
 783                 ret = read_trace(td, bc);
 784                 if (ret < 0)
 785                         goto err_file;
 786                 else if (!ret)
 787                         merge_finish_file(bcs, i, &nr_logs);
 788         }
 789
 790         /* set iolog file to read from the newly merged file */
 791         td->o.read_iolog_file = td->o.merge_blktrace_file;
 792         ret = 0;
 793
 794 err_file:
 795         /* cleanup */
 796         for (i = 0; i < nr_logs; i++) {
 797                 fclose(bcs[i].f);
 798         }
 799 err_merge_buf:
 800         free(merge_buf);
 801 err_out_file:
 802         fflush(merge_fp);
 803         fclose(merge_fp);
 804 err_param:
 805         free(bcs);
 806
 807         return ret;
 808 }