blktrace.c

   1 /*
   2  * blktrace support code for fio
   3  */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7
   8 #include "flist.h"
   9 #include "fio.h"
  10 #include "blktrace.h"
  11 #include "blktrace_api.h"
  12 #include "oslib/linux-dev-lookup.h"
  13
  14 #define TRACE_FIFO_SIZE 8192
  15
  16 /*
  17  * fifo refill frontend, to avoid reading data in trace sized bites
  18  */
  19 static int refill_fifo(struct thread_data *td, struct fifo *fifo, int fd)
  20 {
  21         char buf[TRACE_FIFO_SIZE];
  22         unsigned int total;
  23         int ret;
  24
  25         total = sizeof(buf);
  26         if (total > fifo_room(fifo))
  27                 total = fifo_room(fifo);
  28
  29         ret = read(fd, buf, total);
  30         if (ret < 0) {
  31                 td_verror(td, errno, "read blktrace file");
  32                 return -1;
  33         }
  34
  35         if (ret > 0)
  36                 ret = fifo_put(fifo, buf, ret);
  37
  38         dprint(FD_BLKTRACE, "refill: filled %d bytes\n", ret);
  39         return ret;
  40 }
  41
  42 /*
  43  * Retrieve 'len' bytes from the fifo, refilling if necessary.
  44  */
  45 static int trace_fifo_get(struct thread_data *td, struct fifo *fifo, int fd,
  46                           void *buf, unsigned int len)
  47 {
  48         if (fifo_len(fifo) < len) {
  49                 int ret = refill_fifo(td, fifo, fd);
  50
  51                 if (ret < 0)
  52                         return ret;
  53         }
  54
  55         return fifo_get(fifo, buf, len);
  56 }
  57
  58 /*
  59  * Just discard the pdu by seeking past it.
  60  */
  61 static int discard_pdu(struct thread_data *td, struct fifo *fifo, int fd,
  62                        struct blk_io_trace *t)
  63 {
  64         if (t->pdu_len == 0)
  65                 return 0;
  66
  67         dprint(FD_BLKTRACE, "discard pdu len %u\n", t->pdu_len);
  68         return trace_fifo_get(td, fifo, fd, NULL, t->pdu_len);
  69 }
  70
  71 /*
  72  * Check if this is a blktrace binary data file. We read a single trace
  73  * into memory and check for the magic signature.
  74  */
  75 bool is_blktrace(const char *filename, int *need_swap)
  76 {
  77         struct blk_io_trace t;
  78         int fd, ret;
  79
  80         fd = open(filename, O_RDONLY);
  81         if (fd < 0)
  82                 return false;
  83
  84         ret = read(fd, &t, sizeof(t));
  85         close(fd);
  86
  87         if (ret < 0) {
  88                 perror("read blktrace");
  89                 return false;
  90         } else if (ret != sizeof(t)) {
  91                 log_err("fio: short read on blktrace file\n");
  92                 return false;
  93         }
  94
  95         if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
  96                 *need_swap = 0;
  97                 return true;
  98         }
  99
 100         /*
 101          * Maybe it needs to be endian swapped...
 102          */
 103         t.magic = fio_swap32(t.magic);
 104         if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC) {
 105                 *need_swap = 1;
 106                 return true;
 107         }
 108
 109         return false;
 110 }
 111
 112 #define FMINORBITS      20
 113 #define FMINORMASK      ((1U << FMINORBITS) - 1)
 114 #define FMAJOR(dev)     ((unsigned int) ((dev) >> FMINORBITS))
 115 #define FMINOR(dev)     ((unsigned int) ((dev) & FMINORMASK))
 116
 117 static void trace_add_open_close_event(struct thread_data *td, int fileno, enum file_log_act action)
 118 {
 119         struct io_piece *ipo;
 120
 121         ipo = calloc(1, sizeof(*ipo));
 122         init_ipo(ipo);
 123
 124         ipo->ddir = DDIR_INVAL;
 125         ipo->fileno = fileno;
 126         ipo->file_action = action;
 127         flist_add_tail(&ipo->list, &td->io_log_list);
 128 }
 129
 130 static int trace_add_file(struct thread_data *td, __u32 device)
 131 {
 132         static unsigned int last_maj, last_min, last_fileno;
 133         unsigned int maj = FMAJOR(device);
 134         unsigned int min = FMINOR(device);
 135         struct fio_file *f;
 136         char dev[256];
 137         unsigned int i;
 138
 139         if (last_maj == maj && last_min == min)
 140                 return last_fileno;
 141
 142         last_maj = maj;
 143         last_min = min;
 144
 145         /*
 146          * check for this file in our list
 147          */
 148         for_each_file(td, f, i)
 149                 if (f->major == maj && f->minor == min) {
 150                         last_fileno = f->fileno;
 151                         return last_fileno;
 152                 }
 153
 154         strcpy(dev, "/dev");
 155         if (blktrace_lookup_device(td->o.replay_redirect, dev, maj, min)) {
 156                 int fileno;
 157
 158                 if (td->o.replay_redirect)
 159                         dprint(FD_BLKTRACE, "device lookup: %d/%d\n overridden"
 160                                         " with: %s\n", maj, min,
 161                                         td->o.replay_redirect);
 162                 else
 163                         dprint(FD_BLKTRACE, "device lookup: %d/%d\n", maj, min);
 164
 165                 dprint(FD_BLKTRACE, "add devices %s\n", dev);
 166                 fileno = add_file_exclusive(td, dev);
 167                 td->o.open_files++;
 168                 td->files[fileno]->major = maj;
 169                 td->files[fileno]->minor = min;
 170                 trace_add_open_close_event(td, fileno, FIO_LOG_OPEN_FILE);
 171                 last_fileno = fileno;
 172         }
 173
 174         return last_fileno;
 175 }
 176
 177 static void t_bytes_align(struct thread_options *o, struct blk_io_trace *t)
 178 {
 179         if (!o->replay_align)
 180                 return;
 181
 182         t->bytes = (t->bytes + o->replay_align - 1) & ~(o->replay_align - 1);
 183 }
 184
 185 /*
 186  * Store blk_io_trace data in an ipo for later retrieval.
 187  */
 188 static void store_ipo(struct thread_data *td, unsigned long long offset,
 189                       unsigned int bytes, int rw, unsigned long long ttime,
 190                       int fileno)
 191 {
 192         struct io_piece *ipo;
 193
 194         ipo = calloc(1, sizeof(*ipo));
 195         init_ipo(ipo);
 196
 197         ipo->offset = offset * 512;
 198         if (td->o.replay_scale)
 199                 ipo->offset = ipo->offset / td->o.replay_scale;
 200         ipo_bytes_align(td->o.replay_align, ipo);
 201         ipo->len = bytes;
 202         ipo->delay = ttime / 1000;
 203         if (rw)
 204                 ipo->ddir = DDIR_WRITE;
 205         else
 206                 ipo->ddir = DDIR_READ;
 207         ipo->fileno = fileno;
 208
 209         dprint(FD_BLKTRACE, "store ddir=%d, off=%llu, len=%lu, delay=%lu\n",
 210                                                         ipo->ddir, ipo->offset,
 211                                                         ipo->len, ipo->delay);
 212         queue_io_piece(td, ipo);
 213 }
 214
 215 static void handle_trace_notify(struct blk_io_trace *t)
 216 {
 217         switch (t->action) {
 218         case BLK_TN_PROCESS:
 219                 dprint(FD_BLKTRACE, "got process notify: %x, %d\n",
 220                                 t->action, t->pid);
 221                 break;
 222         case BLK_TN_TIMESTAMP:
 223                 dprint(FD_BLKTRACE, "got timestamp notify: %x, %d\n",
 224                                 t->action, t->pid);
 225                 break;
 226         case BLK_TN_MESSAGE:
 227                 break;
 228         default:
 229                 dprint(FD_BLKTRACE, "unknown trace act %x\n", t->action);
 230                 break;
 231         }
 232 }
 233
 234 static void handle_trace_discard(struct thread_data *td,
 235                                  struct blk_io_trace *t,
 236                                  unsigned long long ttime,
 237                                  unsigned long *ios, unsigned int *bs)
 238 {
 239         struct io_piece *ipo;
 240         int fileno;
 241
 242         if (td->o.replay_skip & (1u << DDIR_TRIM))
 243                 return;
 244
 245         ipo = calloc(1, sizeof(*ipo));
 246         init_ipo(ipo);
 247         fileno = trace_add_file(td, t->device);
 248
 249         ios[DDIR_TRIM]++;
 250         if (t->bytes > bs[DDIR_TRIM])
 251                 bs[DDIR_TRIM] = t->bytes;
 252
 253         td->o.size += t->bytes;
 254
 255         INIT_FLIST_HEAD(&ipo->list);
 256
 257         ipo->offset = t->sector * 512;
 258         if (td->o.replay_scale)
 259                 ipo->offset = ipo->offset / td->o.replay_scale;
 260         ipo_bytes_align(td->o.replay_align, ipo);
 261         ipo->len = t->bytes;
 262         ipo->delay = ttime / 1000;
 263         ipo->ddir = DDIR_TRIM;
 264         ipo->fileno = fileno;
 265
 266         dprint(FD_BLKTRACE, "store discard, off=%llu, len=%lu, delay=%lu\n",
 267                                                         ipo->offset, ipo->len,
 268                                                         ipo->delay);
 269         queue_io_piece(td, ipo);
 270 }
 271
 272 static void dump_trace(struct blk_io_trace *t)
 273 {
 274         log_err("blktrace: ignoring zero byte trace: action=%x\n", t->action);
 275 }
 276
 277 static void handle_trace_fs(struct thread_data *td, struct blk_io_trace *t,
 278                             unsigned long long ttime, unsigned long *ios,
 279                             unsigned int *bs)
 280 {
 281         int rw;
 282         int fileno;
 283
 284         fileno = trace_add_file(td, t->device);
 285
 286         rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
 287
 288         if (rw) {
 289                 if (td->o.replay_skip & (1u << DDIR_WRITE))
 290                         return;
 291         } else {
 292                 if (td->o.replay_skip & (1u << DDIR_READ))
 293                         return;
 294         }
 295
 296         if (!t->bytes) {
 297                 if (!fio_did_warn(FIO_WARN_BTRACE_ZERO))
 298                         dump_trace(t);
 299                 return;
 300         }
 301
 302         if (t->bytes > bs[rw])
 303                 bs[rw] = t->bytes;
 304
 305         ios[rw]++;
 306         td->o.size += t->bytes;
 307         store_ipo(td, t->sector, t->bytes, rw, ttime, fileno);
 308 }
 309
 310 static void handle_trace_flush(struct thread_data *td, struct blk_io_trace *t,
 311                                unsigned long long ttime, unsigned long *ios)
 312 {
 313         struct io_piece *ipo;
 314         int fileno;
 315
 316         if (td->o.replay_skip & (1u << DDIR_SYNC))
 317                 return;
 318
 319         ipo = calloc(1, sizeof(*ipo));
 320         init_ipo(ipo);
 321         fileno = trace_add_file(td, t->device);
 322
 323         ipo->delay = ttime / 1000;
 324         ipo->ddir = DDIR_SYNC;
 325         ipo->fileno = fileno;
 326
 327         ios[DDIR_SYNC]++;
 328         dprint(FD_BLKTRACE, "store flush delay=%lu\n", ipo->delay);
 329         queue_io_piece(td, ipo);
 330 }
 331
 332 /*
 333  * We only care for queue traces, most of the others are side effects
 334  * due to internal workings of the block layer.
 335  */
 336 static void handle_trace(struct thread_data *td, struct blk_io_trace *t,
 337                          unsigned long *ios, unsigned int *bs)
 338 {
 339         static unsigned long long last_ttime;
 340         unsigned long long delay = 0;
 341
 342         if ((t->action & 0xffff) != __BLK_TA_QUEUE)
 343                 return;
 344
 345         if (!(t->action & BLK_TC_ACT(BLK_TC_NOTIFY))) {
 346                 if (!last_ttime || td->o.no_stall)
 347                         delay = 0;
 348                 else if (td->o.replay_time_scale == 100)
 349                         delay = t->time - last_ttime;
 350                 else {
 351                         double tmp = t->time - last_ttime;
 352                         double scale;
 353
 354                         scale = (double) 100.0 / (double) td->o.replay_time_scale;
 355                         tmp *= scale;
 356                         delay = tmp;
 357                 }
 358                 last_ttime = t->time;
 359         }
 360
 361         t_bytes_align(&td->o, t);
 362
 363         if (t->action & BLK_TC_ACT(BLK_TC_NOTIFY))
 364                 handle_trace_notify(t);
 365         else if (t->action & BLK_TC_ACT(BLK_TC_DISCARD))
 366                 handle_trace_discard(td, t, delay, ios, bs);
 367         else if (t->action & BLK_TC_ACT(BLK_TC_FLUSH))
 368                 handle_trace_flush(td, t, delay, ios);
 369         else
 370                 handle_trace_fs(td, t, delay, ios, bs);
 371 }
 372
 373 static void byteswap_trace(struct blk_io_trace *t)
 374 {
 375         t->magic = fio_swap32(t->magic);
 376         t->sequence = fio_swap32(t->sequence);
 377         t->time = fio_swap64(t->time);
 378         t->sector = fio_swap64(t->sector);
 379         t->bytes = fio_swap32(t->bytes);
 380         t->action = fio_swap32(t->action);
 381         t->pid = fio_swap32(t->pid);
 382         t->device = fio_swap32(t->device);
 383         t->cpu = fio_swap32(t->cpu);
 384         t->error = fio_swap16(t->error);
 385         t->pdu_len = fio_swap16(t->pdu_len);
 386 }
 387
 388 static bool t_is_write(struct blk_io_trace *t)
 389 {
 390         return (t->action & BLK_TC_ACT(BLK_TC_WRITE | BLK_TC_DISCARD)) != 0;
 391 }
 392
 393 static enum fio_ddir t_get_ddir(struct blk_io_trace *t)
 394 {
 395         if (t->action & BLK_TC_ACT(BLK_TC_READ))
 396                 return DDIR_READ;
 397         else if (t->action & BLK_TC_ACT(BLK_TC_WRITE))
 398                 return DDIR_WRITE;
 399         else if (t->action & BLK_TC_ACT(BLK_TC_DISCARD))
 400                 return DDIR_TRIM;
 401
 402         return DDIR_INVAL;
 403 }
 404
 405 static void depth_inc(struct blk_io_trace *t, int *depth)
 406 {
 407         enum fio_ddir ddir;
 408
 409         ddir = t_get_ddir(t);
 410         if (ddir != DDIR_INVAL)
 411                 depth[ddir]++;
 412 }
 413
 414 static void depth_dec(struct blk_io_trace *t, int *depth)
 415 {
 416         enum fio_ddir ddir;
 417
 418         ddir = t_get_ddir(t);
 419         if (ddir != DDIR_INVAL)
 420                 depth[ddir]--;
 421 }
 422
 423 static void depth_end(struct blk_io_trace *t, int *this_depth, int *depth)
 424 {
 425         enum fio_ddir ddir = DDIR_INVAL;
 426
 427         ddir = t_get_ddir(t);
 428         if (ddir != DDIR_INVAL) {
 429                 depth[ddir] = max(depth[ddir], this_depth[ddir]);
 430                 this_depth[ddir] = 0;
 431         }
 432 }
 433
 434 /*
 435  * Load a blktrace file by reading all the blk_io_trace entries, and storing
 436  * them as io_pieces like the fio text version would do.
 437  */
 438 bool load_blktrace(struct thread_data *td, const char *filename, int need_swap)
 439 {
 440         struct blk_io_trace t;
 441         unsigned long ios[DDIR_RWDIR_SYNC_CNT] = { };
 442         unsigned int rw_bs[DDIR_RWDIR_CNT] = { };
 443         unsigned long skipped_writes;
 444         struct fifo *fifo;
 445         int fd, i, old_state, max_depth;
 446         struct fio_file *f;
 447         int this_depth[DDIR_RWDIR_CNT] = { };
 448         int depth[DDIR_RWDIR_CNT] = { };
 449
 450         fd = open(filename, O_RDONLY);
 451         if (fd < 0) {
 452                 td_verror(td, errno, "open blktrace file");
 453                 return false;
 454         }
 455
 456         fifo = fifo_alloc(TRACE_FIFO_SIZE);
 457
 458         old_state = td_bump_runstate(td, TD_SETTING_UP);
 459
 460         td->o.size = 0;
 461         skipped_writes = 0;
 462         do {
 463                 int ret = trace_fifo_get(td, fifo, fd, &t, sizeof(t));
 464
 465                 if (ret < 0)
 466                         goto err;
 467                 else if (!ret)
 468                         break;
 469                 else if (ret < (int) sizeof(t)) {
 470                         log_err("fio: short fifo get\n");
 471                         break;
 472                 }
 473
 474                 if (need_swap)
 475                         byteswap_trace(&t);
 476
 477                 if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
 478                         log_err("fio: bad magic in blktrace data: %x\n",
 479                                                                 t.magic);
 480                         goto err;
 481                 }
 482                 if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
 483                         log_err("fio: bad blktrace version %d\n",
 484                                                                 t.magic & 0xff);
 485                         goto err;
 486                 }
 487                 ret = discard_pdu(td, fifo, fd, &t);
 488                 if (ret < 0) {
 489                         td_verror(td, ret, "blktrace lseek");
 490                         goto err;
 491                 } else if (t.pdu_len != ret) {
 492                         log_err("fio: discarded %d of %d\n", ret, t.pdu_len);
 493                         goto err;
 494                 }
 495                 if ((t.action & BLK_TC_ACT(BLK_TC_NOTIFY)) == 0) {
 496                         if ((t.action & 0xffff) == __BLK_TA_QUEUE)
 497                                 depth_inc(&t, this_depth);
 498                         else if (((t.action & 0xffff) == __BLK_TA_BACKMERGE) ||
 499                                 ((t.action & 0xffff) == __BLK_TA_FRONTMERGE))
 500                                 depth_dec(&t, this_depth);
 501                         else if ((t.action & 0xffff) == __BLK_TA_COMPLETE)
 502                                 depth_end(&t, this_depth, depth);
 503
 504                         if (t_is_write(&t) && read_only) {
 505                                 skipped_writes++;
 506                                 continue;
 507                         }
 508                 }
 509
 510                 handle_trace(td, &t, ios, rw_bs);
 511         } while (1);
 512
 513         for_each_file(td, f, i)
 514                 trace_add_open_close_event(td, f->fileno, FIO_LOG_CLOSE_FILE);
 515
 516         fifo_free(fifo);
 517         close(fd);
 518
 519         td_restore_runstate(td, old_state);
 520
 521         if (!td->files_index) {
 522                 log_err("fio: did not find replay device(s)\n");
 523                 return false;
 524         }
 525
 526         /*
 527          * For stacked devices, we don't always get a COMPLETE event so
 528          * the depth grows to insane values. Limit it to something sane(r).
 529          */
 530         max_depth = 0;
 531         for (i = 0; i < DDIR_RWDIR_CNT; i++) {
 532                 if (depth[i] > 1024)
 533                         depth[i] = 1024;
 534                 else if (!depth[i] && ios[i])
 535                         depth[i] = 1;
 536                 max_depth = max(depth[i], max_depth);
 537         }
 538
 539         if (skipped_writes)
 540                 log_err("fio: %s skips replay of %lu writes due to read-only\n",
 541                                                 td->o.name, skipped_writes);
 542
 543         if (!ios[DDIR_READ] && !ios[DDIR_WRITE] && !ios[DDIR_TRIM] &&
 544             !ios[DDIR_SYNC]) {
 545                 log_err("fio: found no ios in blktrace data\n");
 546                 return false;
 547         }
 548
 549         td->o.td_ddir = 0;
 550         if (ios[DDIR_READ]) {
 551                 td->o.td_ddir |= TD_DDIR_READ;
 552                 td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
 553         }
 554         if (ios[DDIR_WRITE]) {
 555                 td->o.td_ddir |= TD_DDIR_WRITE;
 556                 td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
 557         }
 558         if (ios[DDIR_TRIM]) {
 559                 td->o.td_ddir |= TD_DDIR_TRIM;
 560                 td->o.max_bs[DDIR_TRIM] = rw_bs[DDIR_TRIM];
 561         }
 562
 563         /*
 564          * We need to do direct/raw ios to the device, to avoid getting
 565          * read-ahead in our way. But only do so if the minimum block size
 566          * is a multiple of 4k, otherwise we don't know if it's safe to do so.
 567          */
 568         if (!fio_option_is_set(&td->o, odirect) && !(td_min_bs(td) & 4095))
 569                 td->o.odirect = 1;
 570
 571         /*
 572          * If depth wasn't manually set, use probed depth
 573          */
 574         if (!fio_option_is_set(&td->o, iodepth))
 575                 td->o.iodepth = td->o.iodepth_low = max_depth;
 576
 577         return true;
 578 err:
 579         close(fd);
 580         fifo_free(fifo);
 581         return false;
 582 }
 583
 584 static int init_merge_param_list(fio_fp64_t *vals, struct blktrace_cursor *bcs,
 585                                  int nr_logs, int def, size_t off)
 586 {
 587         int i = 0, len = 0;
 588
 589         while (len < FIO_IO_U_LIST_MAX_LEN && vals[len].u.f != 0.0)
 590                 len++;
 591
 592         if (len && len != nr_logs)
 593                 return len;
 594
 595         for (i = 0; i < nr_logs; i++) {
 596                 int *val = (int *)((char *)&bcs[i] + off);
 597                 *val = def;
 598                 if (len)
 599                         *val = (int)vals[i].u.f;
 600         }
 601
 602         return 0;
 603
 604 }
 605
 606 static int find_earliest_io(struct blktrace_cursor *bcs, int nr_logs)
 607 {
 608         __u64 time = ~(__u64)0;
 609         int idx = 0, i;
 610
 611         for (i = 0; i < nr_logs; i++) {
 612                 if (bcs[i].t.time < time) {
 613                         time = bcs[i].t.time;
 614                         idx = i;
 615                 }
 616         }
 617
 618         return idx;
 619 }
 620
 621 static void merge_finish_file(struct blktrace_cursor *bcs, int i, int *nr_logs)
 622 {
 623         bcs[i].iter++;
 624         if (bcs[i].iter < bcs[i].nr_iter) {
 625                 lseek(bcs[i].fd, 0, SEEK_SET);
 626                 return;
 627         }
 628
 629         *nr_logs -= 1;
 630
 631         /* close file */
 632         fifo_free(bcs[i].fifo);
 633         close(bcs[i].fd);
 634
 635         /* keep active files contiguous */
 636         memmove(&bcs[i], &bcs[*nr_logs], sizeof(bcs[i]));
 637 }
 638
 639 static int read_trace(struct thread_data *td, struct blktrace_cursor *bc)
 640 {
 641         int ret = 0;
 642         struct blk_io_trace *t = &bc->t;
 643
 644 read_skip:
 645         /* read an io trace */
 646         ret = trace_fifo_get(td, bc->fifo, bc->fd, t, sizeof(*t));
 647         if (ret < 0) {
 648                 return ret;
 649         } else if (!ret) {
 650                 if (!bc->length)
 651                         bc->length = bc->t.time;
 652                 return ret;
 653         } else if (ret < (int) sizeof(*t)) {
 654                 log_err("fio: short fifo get\n");
 655                 return -1;
 656         }
 657
 658         if (bc->swap)
 659                 byteswap_trace(t);
 660
 661         /* skip over actions that fio does not care about */
 662         if ((t->action & 0xffff) != __BLK_TA_QUEUE ||
 663             t_get_ddir(t) == DDIR_INVAL) {
 664                 ret = discard_pdu(td, bc->fifo, bc->fd, t);
 665                 if (ret < 0) {
 666                         td_verror(td, ret, "blktrace lseek");
 667                         return ret;
 668                 } else if (t->pdu_len != ret) {
 669                         log_err("fio: discarded %d of %d\n", ret,
 670                                 t->pdu_len);
 671                         return -1;
 672                 }
 673                 goto read_skip;
 674         }
 675
 676         t->time = (t->time + bc->iter * bc->length) * bc->scalar / 100;
 677
 678         return ret;
 679 }
 680
 681 static int write_trace(FILE *fp, struct blk_io_trace *t)
 682 {
 683         /* pdu is not used so just write out only the io trace */
 684         t->pdu_len = 0;
 685         return fwrite((void *)t, sizeof(*t), 1, fp);
 686 }
 687
 688 int merge_blktrace_iologs(struct thread_data *td)
 689 {
 690         int nr_logs = get_max_str_idx(td->o.read_iolog_file);
 691         struct blktrace_cursor *bcs = malloc(sizeof(struct blktrace_cursor) *
 692                                              nr_logs);
 693         struct blktrace_cursor *bc;
 694         FILE *merge_fp;
 695         char *str, *ptr, *name, *merge_buf;
 696         int i, ret;
 697
 698         ret = init_merge_param_list(td->o.merge_blktrace_scalars, bcs, nr_logs,
 699                                     100, offsetof(struct blktrace_cursor,
 700                                                   scalar));
 701         if (ret) {
 702                 log_err("fio: merge_blktrace_scalars(%d) != nr_logs(%d)\n",
 703                         ret, nr_logs);
 704                 goto err_param;
 705         }
 706
 707         ret = init_merge_param_list(td->o.merge_blktrace_iters, bcs, nr_logs,
 708                                     1, offsetof(struct blktrace_cursor,
 709                                                 nr_iter));
 710         if (ret) {
 711                 log_err("fio: merge_blktrace_iters(%d) != nr_logs(%d)\n",
 712                         ret, nr_logs);
 713                 goto err_param;
 714         }
 715
 716         /* setup output file */
 717         merge_fp = fopen(td->o.merge_blktrace_file, "w");
 718         merge_buf = malloc(128 * 1024);
 719         ret = setvbuf(merge_fp, merge_buf, _IOFBF, 128 * 1024);
 720         if (ret)
 721                 goto err_out_file;
 722
 723         /* setup input files */
 724         str = ptr = strdup(td->o.read_iolog_file);
 725         nr_logs = 0;
 726         for (i = 0; (name = get_next_str(&ptr)) != NULL; i++) {
 727                 bcs[i].fd = open(name, O_RDONLY);
 728                 if (bcs[i].fd < 0) {
 729                         log_err("fio: could not open file: %s\n", name);
 730                         ret = bcs[i].fd;
 731                         goto err_file;
 732                 }
 733                 bcs[i].fifo = fifo_alloc(TRACE_FIFO_SIZE);
 734                 nr_logs++;
 735
 736                 if (!is_blktrace(name, &bcs[i].swap)) {
 737                         log_err("fio: file is not a blktrace: %s\n", name);
 738                         goto err_file;
 739                 }
 740
 741                 ret = read_trace(td, &bcs[i]);
 742                 if (ret < 0) {
 743                         goto err_file;
 744                 } else if (!ret) {
 745                         merge_finish_file(bcs, i, &nr_logs);
 746                         i--;
 747                 }
 748         }
 749         free(str);
 750
 751         /* merge files */
 752         while (nr_logs) {
 753                 i = find_earliest_io(bcs, nr_logs);
 754                 bc = &bcs[i];
 755                 /* skip over the pdu */
 756                 ret = discard_pdu(td, bc->fifo, bc->fd, &bc->t);
 757                 if (ret < 0) {
 758                         td_verror(td, ret, "blktrace lseek");
 759                         goto err_file;
 760                 } else if (bc->t.pdu_len != ret) {
 761                         log_err("fio: discarded %d of %d\n", ret,
 762                                 bc->t.pdu_len);
 763                         goto err_file;
 764                 }
 765
 766                 ret = write_trace(merge_fp, &bc->t);
 767                 ret = read_trace(td, bc);
 768                 if (ret < 0)
 769                         goto err_file;
 770                 else if (!ret)
 771                         merge_finish_file(bcs, i, &nr_logs);
 772         }
 773
 774         /* set iolog file to read from the newly merged file */
 775         td->o.read_iolog_file = td->o.merge_blktrace_file;
 776         ret = 0;
 777
 778 err_file:
 779         /* cleanup */
 780         for (i = 0; i < nr_logs; i++) {
 781                 fifo_free(bcs[i].fifo);
 782                 close(bcs[i].fd);
 783         }
 784 err_out_file:
 785         fflush(merge_fp);
 786         fclose(merge_fp);
 787         free(merge_buf);
 788 err_param:
 789         free(bcs);
 790
 791         return ret;
 792 }