blktrace.c

   1 /*
   2  * blktrace support code for fio
   3  */
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <sys/stat.h>
   7 #include <dirent.h>
   8
   9 #include "flist.h"
  10 #include "fio.h"
  11 #include "blktrace_api.h"
  12
  13 #define TRACE_FIFO_SIZE 65536
  14
  15 /*
  16  * fifo refill frontend, to avoid reading data in trace sized bites
  17  */
  18 static int refill_fifo(struct thread_data *td, struct fifo *fifo, int fd)
  19 {
  20         char buf[TRACE_FIFO_SIZE];
  21         unsigned int total;
  22         int ret;
  23
  24         total = sizeof(buf);
  25         if (total > fifo_room(fifo))
  26                 total = fifo_room(fifo);
  27
  28         ret = read(fd, buf, total);
  29         if (ret < 0) {
  30                 td_verror(td, errno, "read blktrace file");
  31                 return -1;
  32         }
  33
  34         if (ret > 0)
  35                 ret = fifo_put(fifo, buf, ret);
  36
  37         dprint(FD_BLKTRACE, "refill: filled %d bytes\n", ret);
  38         return ret;
  39 }
  40
  41 /*
  42  * Retrieve 'len' bytes from the fifo, refilling if necessary.
  43  */
  44 static int trace_fifo_get(struct thread_data *td, struct fifo *fifo, int fd,
  45                           void *buf, unsigned int len)
  46 {
  47         if (fifo_len(fifo) < len) {
  48                 int ret = refill_fifo(td, fifo, fd);
  49
  50                 if (ret < 0)
  51                         return ret;
  52         }
  53
  54         return fifo_get(fifo, buf, len);
  55 }
  56
  57 /*
  58  * Just discard the pdu by seeking past it.
  59  */
  60 static int discard_pdu(struct thread_data *td, struct fifo *fifo, int fd,
  61                        struct blk_io_trace *t)
  62 {
  63         if (t->pdu_len == 0)
  64                 return 0;
  65
  66         dprint(FD_BLKTRACE, "discard pdu len %u\n", t->pdu_len);
  67         return trace_fifo_get(td, fifo, fd, NULL, t->pdu_len);
  68 }
  69
  70 /*
  71  * Check if this is a blktrace binary data file. We read a single trace
  72  * into memory and check for the magic signature.
  73  */
  74 int is_blktrace(const char *filename)
  75 {
  76         struct blk_io_trace t;
  77         int fd, ret;
  78
  79         fd = open(filename, O_RDONLY);
  80         if (fd < 0)
  81                 return 0;
  82
  83         ret = read(fd, &t, sizeof(t));
  84         close(fd);
  85
  86         if (ret < 0) {
  87                 perror("read blktrace");
  88                 return 0;
  89         } else if (ret != sizeof(t)) {
  90                 log_err("fio: short read on blktrace file\n");
  91                 return 0;
  92         }
  93
  94         if ((t.magic & 0xffffff00) == BLK_IO_TRACE_MAGIC)
  95                 return 1;
  96
  97         return 0;
  98 }
  99
 100 static int lookup_device(char *path, unsigned int maj, unsigned int min)
 101 {
 102         struct dirent *dir;
 103         struct stat st;
 104         int found = 0;
 105         DIR *D;
 106
 107         D = opendir(path);
 108         if (!D)
 109                 return 0;
 110
 111         while ((dir = readdir(D)) != NULL) {
 112                 char full_path[256];
 113
 114                 if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."))
 115                         continue;
 116
 117                 sprintf(full_path, "%s/%s", path, dir->d_name);
 118                 if (lstat(full_path, &st) == -1) {
 119                         perror("lstat");
 120                         break;
 121                 }
 122
 123                 if (S_ISDIR(st.st_mode)) {
 124                         found = lookup_device(full_path, maj, min);
 125                         if (found) {
 126                                 strcpy(path, full_path);
 127                                 break;
 128                         }
 129                 }
 130
 131                 if (!S_ISBLK(st.st_mode))
 132                         continue;
 133
 134                 if (maj == major(st.st_rdev) && min == minor(st.st_rdev)) {
 135                         dprint(FD_BLKTRACE, "device lookup: %d/%d\n", maj, min);
 136                         strcpy(path, full_path);
 137                         found = 1;
 138                         break;
 139                 }
 140         }
 141
 142         closedir(D);
 143         return found;
 144 }
 145
 146 #define FMINORBITS      20
 147 #define FMINORMASK      ((1U << FMINORBITS) - 1)
 148 #define FMAJOR(dev)     ((unsigned int) ((dev) >> FMINORBITS))
 149 #define FMINOR(dev)     ((unsigned int) ((dev) & FMINORMASK))
 150
 151 static void trace_add_open_event(struct thread_data *td, int fileno)
 152 {
 153         struct io_piece *ipo;
 154
 155         ipo = calloc(1, sizeof(*ipo));
 156
 157         ipo->ddir = DDIR_INVAL;
 158         ipo->fileno = fileno;
 159         ipo->file_action = FIO_LOG_OPEN_FILE;
 160         flist_add_tail(&ipo->list, &td->io_log_list);
 161 }
 162
 163 static void trace_add_file(struct thread_data *td, __u32 device)
 164 {
 165         static unsigned int last_maj, last_min;
 166         unsigned int maj = FMAJOR(device);
 167         unsigned int min = FMINOR(device);
 168         struct fio_file *f;
 169         char dev[256];
 170         unsigned int i;
 171
 172         if (last_maj == maj && last_min == min)
 173                 return;
 174
 175         last_maj = maj;
 176         last_min = min;
 177
 178         /*
 179          * check for this file in our list
 180          */
 181         for_each_file(td, f, i)
 182                 if (f->major == maj && f->minor == min)
 183                         return;
 184
 185         strcpy(dev, "/dev");
 186         if (lookup_device(dev, maj, min)) {
 187                 int fileno;
 188
 189                 dprint(FD_BLKTRACE, "add devices %s\n", dev);
 190                 fileno = add_file(td, dev);
 191                 trace_add_open_event(td, fileno);
 192         }
 193 }
 194
 195 /*
 196  * Store blk_io_trace data in an ipo for later retrieval.
 197  */
 198 static void store_ipo(struct thread_data *td, unsigned long long offset,
 199                       unsigned int bytes, int rw, unsigned long long ttime)
 200 {
 201         struct io_piece *ipo = malloc(sizeof(*ipo));
 202
 203         memset(ipo, 0, sizeof(*ipo));
 204         INIT_FLIST_HEAD(&ipo->list);
 205         /*
 206          * the 512 is wrong here, it should be the hardware sector size...
 207          */
 208         ipo->offset = offset * 512;
 209         ipo->len = bytes;
 210         ipo->delay = ttime / 1000;
 211         if (rw)
 212                 ipo->ddir = DDIR_WRITE;
 213         else
 214                 ipo->ddir = DDIR_READ;
 215
 216         dprint(FD_BLKTRACE, "store ddir=%d, off=%llu, len=%lu, delay=%lu\n",
 217                                                         ipo->ddir, ipo->offset,
 218                                                         ipo->len, ipo->delay);
 219         queue_io_piece(td, ipo);
 220 }
 221
 222 static void handle_trace_notify(struct blk_io_trace *t)
 223 {
 224         switch (t->action) {
 225         case BLK_TN_PROCESS:
 226                 printf("got process notify: %x, %d\n", t->action, t->pid);
 227                 break;
 228         case BLK_TN_TIMESTAMP:
 229                 printf("got timestamp notify: %x, %d\n", t->action, t->pid);
 230                 break;
 231         default:
 232                 dprint(FD_BLKTRACE, "unknown trace act %x\n", t->action);
 233                 break;
 234         }
 235 }
 236
 237 static void handle_trace_fs(struct thread_data *td, struct blk_io_trace *t,
 238                             unsigned long long ttime, unsigned long *ios,
 239                             unsigned int *bs)
 240 {
 241         int rw;
 242
 243         trace_add_file(td, t->device);
 244
 245         rw = (t->action & BLK_TC_ACT(BLK_TC_WRITE)) != 0;
 246
 247         if (t->bytes > bs[rw])
 248                 bs[rw] = t->bytes;
 249
 250         ios[rw]++;
 251         td->o.size += t->bytes;
 252         store_ipo(td, t->sector, t->bytes, rw, ttime);
 253 }
 254
 255 /*
 256  * We only care for queue traces, most of the others are side effects
 257  * due to internal workings of the block layer.
 258  */
 259 static void handle_trace(struct thread_data *td, struct blk_io_trace *t,
 260                          unsigned long long ttime, unsigned long *ios,
 261                          unsigned int *bs)
 262 {
 263         if ((t->action & 0xffff) != __BLK_TA_QUEUE)
 264                 return;
 265         if (t->action & BLK_TC_ACT(BLK_TC_PC))
 266                 return;
 267
 268         if (t->action & BLK_TC_ACT(BLK_TC_NOTIFY))
 269                 handle_trace_notify(t);
 270         else
 271                 handle_trace_fs(td, t, ttime, ios, bs);
 272 }
 273
 274 /*
 275  * Load a blktrace file by reading all the blk_io_trace entries, and storing
 276  * them as io_pieces like the fio text version would do.
 277  */
 278 int load_blktrace(struct thread_data *td, const char *filename)
 279 {
 280         unsigned long long ttime, delay;
 281         struct blk_io_trace t;
 282         unsigned long ios[2], skipped_writes;
 283         unsigned int cpu;
 284         unsigned int rw_bs[2];
 285         struct fifo *fifo;
 286         int fd;
 287
 288         fd = open(filename, O_RDONLY);
 289         if (fd < 0) {
 290                 td_verror(td, errno, "open blktrace file");
 291                 return 1;
 292         }
 293
 294         fifo = fifo_alloc(TRACE_FIFO_SIZE);
 295
 296         td->o.size = 0;
 297
 298         cpu = 0;
 299         ttime = 0;
 300         ios[0] = ios[1] = 0;
 301         rw_bs[0] = rw_bs[1] = 0;
 302         skipped_writes = 0;
 303         do {
 304                 int ret = trace_fifo_get(td, fifo, fd, &t, sizeof(t));
 305
 306                 if (ret < 0)
 307                         goto err;
 308                 else if (!ret)
 309                         break;
 310                 else if (ret < (int) sizeof(t)) {
 311                         log_err("fio: short fifo get\n");
 312                         break;
 313                 }
 314
 315                 if ((t.magic & 0xffffff00) != BLK_IO_TRACE_MAGIC) {
 316                         log_err("fio: bad magic in blktrace data: %x\n",
 317                                                                 t.magic);
 318                         goto err;
 319                 }
 320                 if ((t.magic & 0xff) != BLK_IO_TRACE_VERSION) {
 321                         log_err("fio: bad blktrace version %d\n",
 322                                                                 t.magic & 0xff);
 323                         goto err;
 324                 }
 325                 ret = discard_pdu(td, fifo, fd, &t);
 326                 if (ret < 0) {
 327                         td_verror(td, ret, "blktrace lseek");
 328                         goto err;
 329                 } else if (t.pdu_len != ret) {
 330                         log_err("fio: discarded %d of %d\n", ret, t.pdu_len);
 331                         goto err;
 332                 }
 333                 if ((t.action & BLK_TC_ACT(BLK_TC_NOTIFY)) == 0) {
 334                         if (!ttime) {
 335                                 ttime = t.time;
 336                                 cpu = t.cpu;
 337                         }
 338
 339                         delay = 0;
 340                         if (cpu == t.cpu)
 341                                 delay = t.time - ttime;
 342                         if ((t.action & BLK_TC_ACT(BLK_TC_WRITE)) && read_only)
 343                                 skipped_writes++;
 344                         else
 345                                 handle_trace(td, &t, delay, ios, rw_bs);
 346
 347                         ttime = t.time;
 348                         cpu = t.cpu;
 349                 } else {
 350                         delay = 0;
 351                         handle_trace(td, &t, delay, ios, rw_bs);
 352                 }
 353         } while (1);
 354
 355         fifo_free(fifo);
 356         close(fd);
 357
 358         if (skipped_writes)
 359                 log_err("fio: %s skips replay of %lu writes due to read-only\n",
 360                                                 td->o.name, skipped_writes);
 361
 362         if (!ios[DDIR_READ] && !ios[DDIR_WRITE]) {
 363                 log_err("fio: found no ios in blktrace data\n");
 364                 return 1;
 365         } else if (ios[DDIR_READ] && !ios[DDIR_READ]) {
 366                 td->o.td_ddir = TD_DDIR_READ;
 367                 td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
 368         } else if (!ios[DDIR_READ] && ios[DDIR_WRITE]) {
 369                 td->o.td_ddir = TD_DDIR_WRITE;
 370                 td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
 371         } else {
 372                 td->o.td_ddir = TD_DDIR_RW;
 373                 td->o.max_bs[DDIR_READ] = rw_bs[DDIR_READ];
 374                 td->o.max_bs[DDIR_WRITE] = rw_bs[DDIR_WRITE];
 375         }
 376
 377         /*
 378          * We need to do direct/raw ios to the device, to avoid getting
 379          * read-ahead in our way.
 380          */
 381         td->o.odirect = 1;
 382
 383         return 0;
 384 err:
 385         close(fd);
 386         fifo_free(fifo);
 387         return 1;
 388 }