1 /* 2 * libaio engine 3 * 4 * IO engine using the Linux native aio interface. 5 * 6 */ 7 #include <stdio.h> 8 #include <stdlib.h> 9 #include <unistd.h> 10 #include <errno.h> 11 #include <assert.h> 12 #include <libaio.h> 13 14 #include "../fio.h" 15 #include "../lib/pow2.h" 16 #include "../optgroup.h" 17 18 static int fio_libaio_commit(struct thread_data *td); 19 20 struct libaio_data { 21 io_context_t aio_ctx; 22 struct io_event *aio_events; 23 struct iocb **iocbs; 24 struct io_u **io_us; 25 26 /* 27 * Basic ring buffer. 'head' is incremented in _queue(), and 28 * 'tail' is incremented in _commit(). We keep 'queued' so 29 * that we know if the ring is full or empty, when 30 * 'head' == 'tail'. 'entries' is the ring size, and 31 * 'is_pow2' is just an optimization to use AND instead of 32 * modulus to get the remainder on ring increment. 33 */ 34 int is_pow2; 35 unsigned int entries; 36 unsigned int queued; 37 unsigned int head; 38 unsigned int tail; 39 }; 40 41 struct libaio_options { 42 void *pad; 43 unsigned int userspace_reap; 44 }; 45 46 static struct fio_option options[] = { 47 { 48 .name = "userspace_reap", 49 .lname = "Libaio userspace reaping", 50 .type = FIO_OPT_STR_SET, 51 .off1 = offsetof(struct libaio_options, userspace_reap), 52 .help = "Use alternative user-space reap implementation", 53 .category = FIO_OPT_C_ENGINE, 54 .group = FIO_OPT_G_LIBAIO, 55 }, 56 { 57 .name = NULL, 58 }, 59 }; 60 61 static inline void ring_inc(struct libaio_data *ld, unsigned int *val, 62 unsigned int add) 63 { 64 if (ld->is_pow2) 65 *val = (*val + add) & (ld->entries - 1); 66 else 67 *val = (*val + add) % ld->entries; 68 } 69 70 static int fio_libaio_prep(struct thread_data fio_unused *td, struct io_u *io_u) 71 { 72 struct fio_file *f = io_u->file; 73 74 if (io_u->ddir == DDIR_READ) 75 io_prep_pread(&io_u->iocb, f->fd, io_u->xfer_buf, io_u->xfer_buflen, io_u->offset); 76 else if (io_u->ddir == DDIR_WRITE) 77 io_prep_pwrite(&io_u->iocb, f->fd, io_u->xfer_buf, io_u->xfer_buflen, io_u->offset); 78 else if (ddir_sync(io_u->ddir)) 79 io_prep_fsync(&io_u->iocb, f->fd); 80 81 return 0; 82 } 83 84 static struct io_u *fio_libaio_event(struct thread_data *td, int event) 85 { 86 struct libaio_data *ld = td->io_ops_data; 87 struct io_event *ev; 88 struct io_u *io_u; 89 90 ev = ld->aio_events + event; 91 io_u = container_of(ev->obj, struct io_u, iocb); 92 93 if (ev->res != io_u->xfer_buflen) { 94 if (ev->res > io_u->xfer_buflen) 95 io_u->error = -ev->res; 96 else 97 io_u->resid = io_u->xfer_buflen - ev->res; 98 } else 99 io_u->error = 0; 100 101 return io_u; 102 } 103 104 struct aio_ring { 105 unsigned id; /** kernel internal index number */ 106 unsigned nr; /** number of io_events */ 107 unsigned head; 108 unsigned tail; 109 110 unsigned magic; 111 unsigned compat_features; 112 unsigned incompat_features; 113 unsigned header_length; /** size of aio_ring */ 114 115 struct io_event events[0]; 116 }; 117 118 #define AIO_RING_MAGIC 0xa10a10a1 119 120 static int user_io_getevents(io_context_t aio_ctx, unsigned int max, 121 struct io_event *events) 122 { 123 long i = 0; 124 unsigned head; 125 struct aio_ring *ring = (struct aio_ring*) aio_ctx; 126 127 while (i < max) { 128 head = ring->head; 129 130 if (head == ring->tail) { 131 /* There are no more completions */ 132 break; 133 } else { 134 /* There is another completion to reap */ 135 events[i] = ring->events[head]; 136 read_barrier(); 137 ring->head = (head + 1) % ring->nr; 138 i++; 139 } 140 } 141 142 return i; 143 } 144 145 static int fio_libaio_getevents(struct thread_data *td, unsigned int min, 146 unsigned int max, const struct timespec *t) 147 { 148 struct libaio_data *ld = td->io_ops_data; 149 struct libaio_options *o = td->eo; 150 unsigned actual_min = td->o.iodepth_batch_complete_min == 0 ? 0 : min; 151 struct timespec __lt, *lt = NULL; 152 int r, events = 0; 153 154 if (t) { 155 __lt = *t; 156 lt = &__lt; 157 } 158 159 do { 160 if (o->userspace_reap == 1 161 && actual_min == 0 162 && ((struct aio_ring *)(ld->aio_ctx))->magic 163 == AIO_RING_MAGIC) { 164 r = user_io_getevents(ld->aio_ctx, max, 165 ld->aio_events + events); 166 } else { 167 r = io_getevents(ld->aio_ctx, actual_min, 168 max, ld->aio_events + events, lt); 169 } 170 if (r > 0) 171 events += r; 172 else if ((min && r == 0) || r == -EAGAIN) { 173 fio_libaio_commit(td); 174 usleep(100); 175 } else if (r != -EINTR) 176 break; 177 } while (events < min); 178 179 return r < 0 ? r : events; 180 } 181 182 static int fio_libaio_queue(struct thread_data *td, struct io_u *io_u) 183 { 184 struct libaio_data *ld = td->io_ops_data; 185 186 fio_ro_check(td, io_u); 187 188 if (ld->queued == td->o.iodepth) 189 return FIO_Q_BUSY; 190 191 /* 192 * fsync is tricky, since it can fail and we need to do it 193 * serialized with other io. the reason is that linux doesn't 194 * support aio fsync yet. So return busy for the case where we 195 * have pending io, to let fio complete those first. 196 */ 197 if (ddir_sync(io_u->ddir)) { 198 if (ld->queued) 199 return FIO_Q_BUSY; 200 201 do_io_u_sync(td, io_u); 202 return FIO_Q_COMPLETED; 203 } 204 205 if (io_u->ddir == DDIR_TRIM) { 206 if (ld->queued) 207 return FIO_Q_BUSY; 208 209 do_io_u_trim(td, io_u); 210 return FIO_Q_COMPLETED; 211 } 212 213 ld->iocbs[ld->head] = &io_u->iocb; 214 ld->io_us[ld->head] = io_u; 215 ring_inc(ld, &ld->head, 1); 216 ld->queued++; 217 return FIO_Q_QUEUED; 218 } 219 220 static void fio_libaio_queued(struct thread_data *td, struct io_u **io_us, 221 unsigned int nr) 222 { 223 struct timeval now; 224 unsigned int i; 225 226 if (!fio_fill_issue_time(td)) 227 return; 228 229 fio_gettime(&now, NULL); 230 231 for (i = 0; i < nr; i++) { 232 struct io_u *io_u = io_us[i]; 233 234 memcpy(&io_u->issue_time, &now, sizeof(now)); 235 io_u_queued(td, io_u); 236 } 237 } 238 239 static int fio_libaio_commit(struct thread_data *td) 240 { 241 struct libaio_data *ld = td->io_ops_data; 242 struct iocb **iocbs; 243 struct io_u **io_us; 244 struct timeval tv; 245 int ret, wait_start = 0; 246 247 if (!ld->queued) 248 return 0; 249 250 do { 251 long nr = ld->queued; 252 253 nr = min((unsigned int) nr, ld->entries - ld->tail); 254 io_us = ld->io_us + ld->tail; 255 iocbs = ld->iocbs + ld->tail; 256 257 ret = io_submit(ld->aio_ctx, nr, iocbs); 258 if (ret > 0) { 259 fio_libaio_queued(td, io_us, ret); 260 io_u_mark_submit(td, ret); 261 262 ld->queued -= ret; 263 ring_inc(ld, &ld->tail, ret); 264 ret = 0; 265 wait_start = 0; 266 } else if (ret == -EINTR || !ret) { 267 if (!ret) 268 io_u_mark_submit(td, ret); 269 wait_start = 0; 270 continue; 271 } else if (ret == -EAGAIN) { 272 /* 273 * If we get EAGAIN, we should break out without 274 * error and let the upper layer reap some 275 * events for us. If we have no queued IO, we 276 * must loop here. If we loop for more than 30s, 277 * just error out, something must be buggy in the 278 * IO path. 279 */ 280 if (ld->queued) { 281 ret = 0; 282 break; 283 } 284 if (!wait_start) { 285 fio_gettime(&tv, NULL); 286 wait_start = 1; 287 } else if (mtime_since_now(&tv) > 30000) { 288 log_err("fio: aio appears to be stalled, giving up\n"); 289 break; 290 } 291 usleep(1); 292 continue; 293 } else if (ret == -ENOMEM) { 294 /* 295 * If we get -ENOMEM, reap events if we can. If 296 * we cannot, treat it as a fatal event since there's 297 * nothing we can do about it. 298 */ 299 if (ld->queued) 300 ret = 0; 301 break; 302 } else 303 break; 304 } while (ld->queued); 305 306 return ret; 307 } 308 309 static int fio_libaio_cancel(struct thread_data *td, struct io_u *io_u) 310 { 311 struct libaio_data *ld = td->io_ops_data; 312 313 return io_cancel(ld->aio_ctx, &io_u->iocb, ld->aio_events); 314 } 315 316 static void fio_libaio_cleanup(struct thread_data *td) 317 { 318 struct libaio_data *ld = td->io_ops_data; 319 320 if (ld) { 321 /* 322 * Work-around to avoid huge RCU stalls at exit time. If we 323 * don't do this here, then it'll be torn down by exit_aio(). 324 * But for that case we can parallellize the freeing, thus 325 * speeding it up a lot. 326 */ 327 if (!(td->flags & TD_F_CHILD)) 328 io_destroy(ld->aio_ctx); 329 free(ld->aio_events); 330 free(ld->iocbs); 331 free(ld->io_us); 332 free(ld); 333 } 334 } 335 336 static int fio_libaio_init(struct thread_data *td) 337 { 338 struct libaio_options *o = td->eo; 339 struct libaio_data *ld; 340 int err = 0; 341 342 ld = calloc(1, sizeof(*ld)); 343 344 /* 345 * First try passing in 0 for queue depth, since we don't 346 * care about the user ring. If that fails, the kernel is too old 347 * and we need the right depth. 348 */ 349 if (!o->userspace_reap) 350 err = io_queue_init(INT_MAX, &ld->aio_ctx); 351 if (o->userspace_reap || err == -EINVAL) 352 err = io_queue_init(td->o.iodepth, &ld->aio_ctx); 353 if (err) { 354 td_verror(td, -err, "io_queue_init"); 355 log_err("fio: check /proc/sys/fs/aio-max-nr\n"); 356 free(ld); 357 return 1; 358 } 359 360 ld->entries = td->o.iodepth; 361 ld->is_pow2 = is_power_of_2(ld->entries); 362 ld->aio_events = calloc(ld->entries, sizeof(struct io_event)); 363 ld->iocbs = calloc(ld->entries, sizeof(struct iocb *)); 364 ld->io_us = calloc(ld->entries, sizeof(struct io_u *)); 365 366 td->io_ops_data = ld; 367 return 0; 368 } 369 370 static struct ioengine_ops ioengine = { 371 .name = "libaio", 372 .version = FIO_IOOPS_VERSION, 373 .init = fio_libaio_init, 374 .prep = fio_libaio_prep, 375 .queue = fio_libaio_queue, 376 .commit = fio_libaio_commit, 377 .cancel = fio_libaio_cancel, 378 .getevents = fio_libaio_getevents, 379 .event = fio_libaio_event, 380 .cleanup = fio_libaio_cleanup, 381 .open_file = generic_open_file, 382 .close_file = generic_close_file, 383 .get_file_size = generic_get_file_size, 384 .options = options, 385 .option_struct_size = sizeof(struct libaio_options), 386 }; 387 388 static void fio_init fio_libaio_register(void) 389 { 390 register_ioengine(&ioengine); 391 } 392 393 static void fio_exit fio_libaio_unregister(void) 394 { 395 unregister_ioengine(&ioengine); 396 } 397
