t/aio-ring.c

   1 /*
   2  * gcc -D_GNU_SOURCE -Wall -O2 -o aio-ring aio-ring.c  -lpthread -laio
   3  */
   4 #include <stdio.h>
   5 #include <errno.h>
   6 #include <assert.h>
   7 #include <stdlib.h>
   8 #include <stddef.h>
   9 #include <signal.h>
  10 #include <inttypes.h>
  11
  12 #include <sys/types.h>
  13 #include <sys/stat.h>
  14 #include <sys/ioctl.h>
  15 #include <sys/syscall.h>
  16 #include <sys/resource.h>
  17 #include <linux/fs.h>
  18 #include <fcntl.h>
  19 #include <unistd.h>
  20 #include <libaio.h>
  21 #include <string.h>
  22 #include <pthread.h>
  23 #include <sched.h>
  24
  25 #define IOCB_FLAG_HIPRI         (1 << 2)
  26
  27 #define IOCTX_FLAG_IOPOLL       (1 << 1)
  28 #define IOCTX_FLAG_USERIOCB     (1 << 0)
  29 #define IOCTX_FLAG_FIXEDBUFS    (1 << 2)
  30 #define IOCTX_FLAG_SCQRING      (1 << 3)        /* Use SQ/CQ rings */
  31 #define IOCTX_FLAG_SQTHREAD     (1 << 4)        /* Use SQ thread */
  32 #define IOCTX_FLAG_SQWQ         (1 << 5)        /* Use SQ wq */
  33
  34 #define barrier()       __asm__ __volatile__("": : :"memory")
  35
  36 #define min(a, b)               ((a < b) ? (a) : (b))
  37
  38 typedef uint32_t u32;
  39
  40 struct aio_iocb_ring {
  41         union {
  42                 struct {
  43                         u32 head, tail;
  44                         u32 nr_events;
  45                         u32 sq_thread_cpu;
  46                 };
  47                 struct iocb pad_iocb;
  48         };
  49         struct iocb iocbs[0];
  50 };
  51
  52 struct aio_io_event_ring {
  53         union {
  54                 struct {
  55                         u32 head, tail;
  56                         u32 nr_events;
  57                 };
  58                 struct io_event pad_event;
  59         };
  60         struct io_event events[0];
  61 };
  62
  63 #define IORING_FLAG_SUBMIT      (1 << 0)
  64 #define IORING_FLAG_GETEVENTS   (1 << 1)
  65
  66 #define DEPTH                   32
  67 #define RING_SIZE               (DEPTH + 1)
  68
  69 #define BATCH_SUBMIT            8
  70 #define BATCH_COMPLETE          8
  71
  72 #define BS                      4096
  73
  74 struct submitter {
  75         pthread_t thread;
  76         unsigned long max_blocks;
  77         io_context_t ioc;
  78         struct drand48_data rand;
  79         struct aio_iocb_ring *sq_ring;
  80         struct aio_io_event_ring *cq_ring;
  81         int inflight;
  82         unsigned long reaps;
  83         unsigned long done;
  84         unsigned long calls;
  85         volatile int finish;
  86         char filename[128];
  87 };
  88
  89 static struct submitter submitters[1];
  90 static volatile int finish;
  91
  92 static int polled = 1;          /* use IO polling */
  93 static int fixedbufs = 1;       /* use fixed user buffers */
  94 static int buffered = 0;        /* use buffered IO, not O_DIRECT */
  95 static int sq_thread = 0;       /* use kernel submission thread */
  96 static int sq_thread_cpu = 0;   /* pin above thread to this CPU */
  97
  98 static int io_setup2(unsigned int nr_events, unsigned int flags,
  99                      struct iocb *iocbs, struct aio_iocb_ring *sq_ring,
 100                      struct aio_io_event_ring *cq_ring, io_context_t *ctx_idp)
 101 {
 102         return syscall(335, nr_events, flags, iocbs, sq_ring, cq_ring, ctx_idp);
 103 }
 104
 105 static int io_ring_enter(io_context_t ctx, unsigned int to_submit,
 106                          unsigned int min_complete, unsigned int flags)
 107 {
 108         return syscall(336, ctx, to_submit, min_complete, flags);
 109 }
 110
 111 static int gettid(void)
 112 {
 113         return syscall(__NR_gettid);
 114 }
 115
 116 static void init_io(struct submitter *s, int fd, struct iocb *iocb)
 117 {
 118         unsigned long offset;
 119         long r;
 120
 121         lrand48_r(&s->rand, &r);
 122         offset = (r % (s->max_blocks - 1)) * BS;
 123
 124         iocb->aio_fildes = fd;
 125         iocb->aio_lio_opcode = IO_CMD_PREAD;
 126         iocb->u.c.offset = offset;
 127         if (polled)
 128                 iocb->u.c.flags = IOCB_FLAG_HIPRI;
 129         if (!fixedbufs)
 130                 iocb->u.c.nbytes = BS;
 131 }
 132
 133 static int prep_more_ios(struct submitter *s, int fd, int max_ios)
 134 {
 135         struct aio_iocb_ring *ring = s->sq_ring;
 136         struct iocb *iocb;
 137         u32 tail, next_tail, prepped = 0;
 138
 139         next_tail = tail = ring->tail;
 140         do {
 141                 next_tail++;
 142                 if (next_tail == ring->nr_events)
 143                         next_tail = 0;
 144
 145                 barrier();
 146                 if (next_tail == ring->head)
 147                         break;
 148
 149                 iocb = &s->sq_ring->iocbs[tail];
 150                 init_io(s, fd, iocb);
 151                 prepped++;
 152                 tail = next_tail;
 153         } while (prepped < max_ios);
 154
 155         if (ring->tail != tail) {
 156                 /* order tail store with writes to iocbs above */
 157                 barrier();
 158                 ring->tail = tail;
 159                 barrier();
 160         }
 161         return prepped;
 162 }
 163
 164 static int get_file_size(int fd, unsigned long *blocks)
 165 {
 166         struct stat st;
 167
 168         if (fstat(fd, &st) < 0)
 169                 return -1;
 170         if (S_ISBLK(st.st_mode)) {
 171                 unsigned long long bytes;
 172
 173                 if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
 174                         return -1;
 175
 176                 *blocks = bytes / BS;
 177                 return 0;
 178         } else if (S_ISREG(st.st_mode)) {
 179                 *blocks = st.st_size / BS;
 180                 return 0;
 181         }
 182
 183         return -1;
 184 }
 185
 186 static int reap_events(struct submitter *s)
 187 {
 188         struct aio_io_event_ring *ring = s->cq_ring;
 189         struct io_event *ev;
 190         u32 head, reaped = 0;
 191
 192         head = ring->head;
 193         do {
 194                 barrier();
 195                 if (head == ring->tail)
 196                         break;
 197                 ev = &ring->events[head];
 198                 if (ev->res != BS) {
 199                         int index = (int) (uintptr_t) ev->obj;
 200                         struct iocb *iocb = &s->sq_ring->iocbs[index];
 201
 202                         printf("io: unexpected ret=%ld\n", ev->res);
 203                         printf("offset=%lu, size=%lu\n", (unsigned long) iocb->u.c.offset, (unsigned long) iocb->u.c.nbytes);
 204                         return -1;
 205                 }
 206                 reaped++;
 207                 head++;
 208                 if (head == ring->nr_events)
 209                         head = 0;
 210         } while (1);
 211
 212         s->inflight -= reaped;
 213         ring->head = head;
 214         barrier();
 215         return reaped;
 216 }
 217
 218 static void *submitter_fn(void *data)
 219 {
 220         struct submitter *s = data;
 221         int fd, ret, prepped, flags;
 222
 223         printf("submitter=%d\n", gettid());
 224
 225         flags = O_RDONLY;
 226         if (!buffered)
 227                 flags |= O_DIRECT;
 228         fd = open(s->filename, flags);
 229         if (fd < 0) {
 230                 perror("open");
 231                 goto done;
 232         }
 233
 234         if (get_file_size(fd, &s->max_blocks)) {
 235                 printf("failed getting size of device/file\n");
 236                 goto err;
 237         }
 238         if (!s->max_blocks) {
 239                 printf("Zero file/device size?\n");
 240                 goto err;
 241         }
 242
 243         s->max_blocks--;
 244
 245         srand48_r(pthread_self(), &s->rand);
 246
 247         prepped = 0;
 248         do {
 249                 int to_wait, flags, to_submit, this_reap;
 250
 251                 if (!prepped && s->inflight < DEPTH)
 252                         prepped = prep_more_ios(s, fd, min(DEPTH - s->inflight, BATCH_SUBMIT));
 253                 s->inflight += prepped;
 254 submit_more:
 255                 to_submit = prepped;
 256 submit:
 257                 if (s->inflight + BATCH_SUBMIT < DEPTH)
 258                         to_wait = 0;
 259                 else
 260                         to_wait = min(s->inflight + to_submit, BATCH_COMPLETE);
 261
 262                 flags = IORING_FLAG_GETEVENTS;
 263                 if (to_submit)
 264                         flags |= IORING_FLAG_SUBMIT;
 265
 266                 ret = io_ring_enter(s->ioc, to_submit, to_wait, flags);
 267                 s->calls++;
 268
 269                 this_reap = reap_events(s);
 270                 if (this_reap == -1)
 271                         break;
 272                 s->reaps += this_reap;
 273
 274                 if (ret >= 0) {
 275                         if (!ret) {
 276                                 to_submit = 0;
 277                                 if (s->inflight)
 278                                         goto submit;
 279                                 continue;
 280                         } else if (ret < to_submit) {
 281                                 int diff = to_submit - ret;
 282
 283                                 s->done += ret;
 284                                 prepped -= diff;
 285                                 goto submit_more;
 286                         }
 287                         s->done += ret;
 288                         prepped = 0;
 289                         continue;
 290                 } else if (ret < 0) {
 291                         if ((ret == -1 && errno == EAGAIN) || ret == -EAGAIN) {
 292                                 if (s->finish)
 293                                         break;
 294                                 if (this_reap)
 295                                         goto submit;
 296                                 to_submit = 0;
 297                                 goto submit;
 298                         }
 299                         if (ret == -1)
 300                                 printf("io_submit: %s\n", strerror(errno));
 301                         else
 302                                 printf("io_submit: %s\n", strerror(-ret));
 303                         break;
 304                 }
 305         } while (!s->finish);
 306 err:
 307         close(fd);
 308 done:
 309         finish = 1;
 310         return NULL;
 311 }
 312
 313 static void sig_int(int sig)
 314 {
 315         printf("Exiting on signal %d\n", sig);
 316         submitters[0].finish = 1;
 317         finish = 1;
 318 }
 319
 320 static void arm_sig_int(void)
 321 {
 322         struct sigaction act;
 323
 324         memset(&act, 0, sizeof(act));
 325         act.sa_handler = sig_int;
 326         act.sa_flags = SA_RESTART;
 327         sigaction(SIGINT, &act, NULL);
 328 }
 329
 330 int main(int argc, char *argv[])
 331 {
 332         struct submitter *s = &submitters[0];
 333         unsigned long done, calls, reap;
 334         int flags = 0, err;
 335         int j;
 336         size_t size;
 337         void *p, *ret;
 338         struct rlimit rlim;
 339
 340         if (argc < 2) {
 341                 printf("%s: filename\n", argv[0]);
 342                 return 1;
 343         }
 344
 345         rlim.rlim_cur = RLIM_INFINITY;
 346         rlim.rlim_max = RLIM_INFINITY;
 347         if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
 348                 perror("setrlimit");
 349                 return 1;
 350         }
 351
 352         arm_sig_int();
 353
 354         size = sizeof(struct aio_iocb_ring) + RING_SIZE * sizeof(struct iocb);
 355         if (posix_memalign(&p, 4096, size))
 356                 return 1;
 357         s->sq_ring = p;
 358         memset(p, 0, size);
 359
 360         size = sizeof(struct aio_io_event_ring) + RING_SIZE * sizeof(struct io_event);
 361         if (posix_memalign(&p, 4096, size))
 362                 return 1;
 363         s->cq_ring = p;
 364         memset(p, 0, size);
 365
 366         for (j = 0; j < RING_SIZE; j++) {
 367                 struct iocb *iocb = &s->sq_ring->iocbs[j];
 368
 369                 if (posix_memalign(&iocb->u.c.buf, BS, BS)) {
 370                         printf("failed alloc\n");
 371                         return 1;
 372                 }
 373                 iocb->u.c.nbytes = BS;
 374         }
 375
 376         flags = IOCTX_FLAG_SCQRING;
 377         if (polled)
 378                 flags |= IOCTX_FLAG_IOPOLL;
 379         if (fixedbufs)
 380                 flags |= IOCTX_FLAG_FIXEDBUFS;
 381         if (buffered)
 382                 flags |= IOCTX_FLAG_SQWQ;
 383         else if (sq_thread) {
 384                 flags |= IOCTX_FLAG_SQTHREAD;
 385                 s->sq_ring->sq_thread_cpu = sq_thread_cpu;
 386         }
 387
 388         err = io_setup2(RING_SIZE, flags, s->sq_ring->iocbs, s->sq_ring, s->cq_ring, &s->ioc);
 389         if (err) {
 390                 printf("ctx_init failed: %s, %d\n", strerror(errno), err);
 391                 return 1;
 392         }
 393         printf("polled=%d, fixedbufs=%d, buffered=%d\n", polled, fixedbufs, buffered);
 394         printf("  QD=%d, sq_ring=%d, cq_ring=%d\n", DEPTH, s->sq_ring->nr_events, s->cq_ring->nr_events);
 395         strcpy(s->filename, argv[1]);
 396
 397         pthread_create(&s->thread, NULL, submitter_fn, s);
 398
 399         reap = calls = done = 0;
 400         do {
 401                 unsigned long this_done = 0;
 402                 unsigned long this_reap = 0;
 403                 unsigned long this_call = 0;
 404                 unsigned long rpc = 0, ipc = 0;
 405
 406                 sleep(1);
 407                 this_done += s->done;
 408                 this_call += s->calls;
 409                 this_reap += s->reaps;
 410                 if (this_call - calls) {
 411                         rpc = (this_done - done) / (this_call - calls);
 412                         ipc = (this_reap - reap) / (this_call - calls);
 413                 }
 414                 printf("IOPS=%lu, IOS/call=%lu/%lu, inflight=%u (head=%d tail=%d), %lu, %lu\n",
 415                                 this_done - done, rpc, ipc, s->inflight,
 416                                 s->cq_ring->head, s->cq_ring->tail, s->reaps, s->done);
 417                 done = this_done;
 418                 calls = this_call;
 419                 reap = this_reap;
 420         } while (!finish);
 421
 422         pthread_join(s->thread, &ret);
 423         return 0;
 424 }