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 <sys/mman.h>
  18 #include <linux/fs.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <libaio.h>
  22 #include <string.h>
  23 #include <pthread.h>
  24 #include <sched.h>
  25
  26 #define IOCTX_FLAG_SCQRING      (1 << 0)        /* Use SQ/CQ rings */
  27 #define IOCTX_FLAG_IOPOLL       (1 << 1)
  28 #define IOCTX_FLAG_FIXEDBUFS    (1 << 2)
  29 #define IOCTX_FLAG_SQTHREAD     (1 << 3)        /* Use SQ thread */
  30 #define IOCTX_FLAG_SQWQ         (1 << 4)        /* Use SQ wq */
  31 #define IOCTX_FLAG_SQPOLL       (1 << 5)
  32
  33 #define IOEV_RES2_CACHEHIT      (1 << 0)
  34
  35 #define barrier()       __asm__ __volatile__("": : :"memory")
  36
  37 #define min(a, b)               ((a < b) ? (a) : (b))
  38
  39 typedef uint64_t u64;
  40 typedef uint32_t u32;
  41 typedef uint16_t u16;
  42
  43 #define IORING_OFF_SQ_RING      0ULL
  44 #define IORING_OFF_CQ_RING      0x8000000ULL
  45 #define IORING_OFF_IOCB         0x10000000ULL
  46
  47 struct aio_uring_offsets {
  48         u32 head;
  49         u32 tail;
  50         u32 ring_mask;
  51         u32 ring_entries;
  52         u32 flags;
  53         u32 elems;
  54 };
  55
  56 struct aio_uring_params {
  57         u32 sq_entries;
  58         u32 cq_entries;
  59         u32 flags;
  60         u16 sq_thread_cpu;
  61         u16 resv[9];
  62         struct aio_uring_offsets sq_off;
  63         struct aio_uring_offsets cq_off;
  64 };
  65
  66 struct aio_sq_ring {
  67         u32 *head;
  68         u32 *tail;
  69         u32 *ring_mask;
  70         u32 *ring_entries;
  71         u32 *array;
  72 };
  73
  74 struct aio_cq_ring {
  75         u32 *head;
  76         u32 *tail;
  77         u32 *ring_mask;
  78         u32 *ring_entries;
  79         struct io_event *events;
  80 };
  81
  82 #define IORING_ENTER_GETEVENTS  (1 << 0)
  83
  84 #define DEPTH                   32
  85
  86 #define BATCH_SUBMIT            8
  87 #define BATCH_COMPLETE          8
  88
  89 #define BS                      4096
  90
  91 static unsigned sq_ring_mask, cq_ring_mask;
  92
  93 struct submitter {
  94         pthread_t thread;
  95         unsigned long max_blocks;
  96         int fd;
  97         struct drand48_data rand;
  98         struct aio_sq_ring sq_ring;
  99         struct iocb *iocbs;
 100         struct iovec iovecs[DEPTH];
 101         struct aio_cq_ring cq_ring;
 102         int inflight;
 103         unsigned long reaps;
 104         unsigned long done;
 105         unsigned long calls;
 106         unsigned long cachehit, cachemiss;
 107         volatile int finish;
 108         char filename[128];
 109 };
 110
 111 static struct submitter submitters[1];
 112 static volatile int finish;
 113
 114 static int polled = 0;          /* use IO polling */
 115 static int fixedbufs = 0;       /* use fixed user buffers */
 116 static int buffered = 1;        /* use buffered IO, not O_DIRECT */
 117 static int sq_thread = 0;       /* use kernel submission thread */
 118 static int sq_thread_cpu = 0;   /* pin above thread to this CPU */
 119
 120 static int io_uring_setup(unsigned entries, struct iovec *iovecs,
 121                           struct aio_uring_params *p)
 122 {
 123         return syscall(335, entries, iovecs, p);
 124 }
 125
 126 static int io_uring_enter(struct submitter *s, unsigned int to_submit,
 127                           unsigned int min_complete, unsigned int flags)
 128 {
 129         return syscall(336, s->fd, to_submit, min_complete, flags);
 130 }
 131
 132 static int gettid(void)
 133 {
 134         return syscall(__NR_gettid);
 135 }
 136
 137 static void init_io(struct submitter *s, int fd, unsigned index)
 138 {
 139         struct iocb *iocb = &s->iocbs[index];
 140         unsigned long offset;
 141         long r;
 142
 143         lrand48_r(&s->rand, &r);
 144         offset = (r % (s->max_blocks - 1)) * BS;
 145
 146         iocb->aio_fildes = fd;
 147         iocb->aio_lio_opcode = IO_CMD_PREAD;
 148         iocb->u.c.buf = s->iovecs[index].iov_base;
 149         iocb->u.c.nbytes = BS;
 150         iocb->u.c.offset = offset;
 151 }
 152
 153 static int prep_more_ios(struct submitter *s, int fd, int max_ios)
 154 {
 155         struct aio_sq_ring *ring = &s->sq_ring;
 156         u32 index, tail, next_tail, prepped = 0;
 157
 158         next_tail = tail = *ring->tail;
 159         do {
 160                 next_tail++;
 161                 barrier();
 162                 if (next_tail == *ring->head)
 163                         break;
 164
 165                 index = tail & sq_ring_mask;
 166                 init_io(s, fd, index);
 167                 ring->array[index] = index;
 168                 prepped++;
 169                 tail = next_tail;
 170         } while (prepped < max_ios);
 171
 172         if (*ring->tail != tail) {
 173                 /* order tail store with writes to iocbs above */
 174                 barrier();
 175                 *ring->tail = tail;
 176                 barrier();
 177         }
 178         return prepped;
 179 }
 180
 181 static int get_file_size(int fd, unsigned long *blocks)
 182 {
 183         struct stat st;
 184
 185         if (fstat(fd, &st) < 0)
 186                 return -1;
 187         if (S_ISBLK(st.st_mode)) {
 188                 unsigned long long bytes;
 189
 190                 if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
 191                         return -1;
 192
 193                 *blocks = bytes / BS;
 194                 return 0;
 195         } else if (S_ISREG(st.st_mode)) {
 196                 *blocks = st.st_size / BS;
 197                 return 0;
 198         }
 199
 200         return -1;
 201 }
 202
 203 static int reap_events(struct submitter *s)
 204 {
 205         struct aio_cq_ring *ring = &s->cq_ring;
 206         struct io_event *ev;
 207         u32 head, reaped = 0;
 208
 209         head = *ring->head;
 210         do {
 211                 barrier();
 212                 if (head == *ring->tail)
 213                         break;
 214                 ev = &ring->events[head & cq_ring_mask];
 215                 if (ev->res != BS) {
 216                         struct iocb *iocb = ev->obj;
 217
 218                         printf("io: unexpected ret=%ld\n", ev->res);
 219                         printf("offset=%lu, size=%lu\n", (unsigned long) iocb->u.c.offset, (unsigned long) iocb->u.c.nbytes);
 220                         return -1;
 221                 }
 222                 if (ev->res2 & IOEV_RES2_CACHEHIT)
 223                         s->cachehit++;
 224                 else
 225                         s->cachemiss++;
 226                 reaped++;
 227                 head++;
 228         } while (1);
 229
 230         s->inflight -= reaped;
 231         *ring->head = head;
 232         barrier();
 233         return reaped;
 234 }
 235
 236 static void *submitter_fn(void *data)
 237 {
 238         struct submitter *s = data;
 239         int fd, ret, prepped, flags;
 240
 241         printf("submitter=%d\n", gettid());
 242
 243         flags = O_RDONLY;
 244         if (!buffered)
 245                 flags |= O_DIRECT;
 246         fd = open(s->filename, flags);
 247         if (fd < 0) {
 248                 perror("open");
 249                 goto done;
 250         }
 251
 252         if (get_file_size(fd, &s->max_blocks)) {
 253                 printf("failed getting size of device/file\n");
 254                 goto err;
 255         }
 256         if (!s->max_blocks) {
 257                 printf("Zero file/device size?\n");
 258                 goto err;
 259         }
 260
 261         s->max_blocks--;
 262
 263         srand48_r(pthread_self(), &s->rand);
 264
 265         prepped = 0;
 266         do {
 267                 int to_wait, to_submit, this_reap;
 268
 269                 if (!prepped && s->inflight < DEPTH)
 270                         prepped = prep_more_ios(s, fd, min(DEPTH - s->inflight, BATCH_SUBMIT));
 271                 s->inflight += prepped;
 272 submit_more:
 273                 to_submit = prepped;
 274 submit:
 275                 if (s->inflight + BATCH_SUBMIT < DEPTH)
 276                         to_wait = 0;
 277                 else
 278                         to_wait = min(s->inflight + to_submit, BATCH_COMPLETE);
 279
 280                 ret = io_uring_enter(s, to_submit, to_wait, IORING_ENTER_GETEVENTS);
 281                 s->calls++;
 282
 283                 this_reap = reap_events(s);
 284                 if (this_reap == -1)
 285                         break;
 286                 s->reaps += this_reap;
 287
 288                 if (ret >= 0) {
 289                         if (!ret) {
 290                                 to_submit = 0;
 291                                 if (s->inflight)
 292                                         goto submit;
 293                                 continue;
 294                         } else if (ret < to_submit) {
 295                                 int diff = to_submit - ret;
 296
 297                                 s->done += ret;
 298                                 prepped -= diff;
 299                                 goto submit_more;
 300                         }
 301                         s->done += ret;
 302                         prepped = 0;
 303                         continue;
 304                 } else if (ret < 0) {
 305                         if ((ret == -1 && errno == EAGAIN) || ret == -EAGAIN) {
 306                                 if (s->finish)
 307                                         break;
 308                                 if (this_reap)
 309                                         goto submit;
 310                                 to_submit = 0;
 311                                 goto submit;
 312                         }
 313                         if (ret == -1)
 314                                 printf("io_submit: %s\n", strerror(errno));
 315                         else
 316                                 printf("io_submit: %s\n", strerror(-ret));
 317                         break;
 318                 }
 319         } while (!s->finish);
 320 err:
 321         close(fd);
 322 done:
 323         finish = 1;
 324         return NULL;
 325 }
 326
 327 static void sig_int(int sig)
 328 {
 329         printf("Exiting on signal %d\n", sig);
 330         submitters[0].finish = 1;
 331         finish = 1;
 332 }
 333
 334 static void arm_sig_int(void)
 335 {
 336         struct sigaction act;
 337
 338         memset(&act, 0, sizeof(act));
 339         act.sa_handler = sig_int;
 340         act.sa_flags = SA_RESTART;
 341         sigaction(SIGINT, &act, NULL);
 342 }
 343
 344 static int setup_ring(struct submitter *s)
 345 {
 346         struct aio_sq_ring *sring = &s->sq_ring;
 347         struct aio_cq_ring *cring = &s->cq_ring;
 348         struct aio_uring_params p;
 349         void *ptr;
 350         int fd;
 351
 352         memset(&p, 0, sizeof(p));
 353
 354         p.flags = IOCTX_FLAG_SCQRING;
 355         if (polled)
 356                 p.flags |= IOCTX_FLAG_IOPOLL;
 357         if (fixedbufs)
 358                 p.flags |= IOCTX_FLAG_FIXEDBUFS;
 359         if (buffered)
 360                 p.flags |= IOCTX_FLAG_SQWQ;
 361         else if (sq_thread) {
 362                 p.flags |= IOCTX_FLAG_SQTHREAD;
 363                 p.sq_thread_cpu = sq_thread_cpu;
 364         }
 365
 366         if (fixedbufs)
 367                 fd = io_uring_setup(DEPTH, s->iovecs, &p);
 368         else
 369                 fd = io_uring_setup(DEPTH, NULL, &p);
 370         if (fd < 0) {
 371                 perror("io_uring_setup");
 372                 return 1;
 373         }
 374
 375         s->fd = fd;
 376
 377         ptr = mmap(0, p.sq_off.elems + p.sq_entries * sizeof(u32),
 378                         PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
 379                         fd, IORING_OFF_SQ_RING);
 380         printf("sq_ring ptr = 0x%p\n", ptr);
 381         sring->head = ptr + p.sq_off.head;
 382         sring->tail = ptr + p.sq_off.tail;
 383         sring->ring_mask = ptr + p.sq_off.ring_mask;
 384         sring->ring_entries = ptr + p.sq_off.ring_entries;
 385         sring->array = ptr + p.sq_off.elems;
 386         sq_ring_mask = *sring->ring_mask;
 387
 388         s->iocbs = mmap(0, p.sq_entries * sizeof(struct iocb), PROT_READ | PROT_WRITE,
 389                         MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_IOCB);
 390         printf("iocbs ptr   = 0x%p\n", s->iocbs);
 391
 392         ptr = mmap(0, p.cq_off.elems + p.cq_entries * sizeof(struct io_event),
 393                         PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
 394                         fd, IORING_OFF_CQ_RING);
 395         printf("cq_ring ptr = 0x%p\n", ptr);
 396         cring->head = ptr + p.cq_off.head;
 397         cring->tail = ptr + p.cq_off.tail;
 398         cring->ring_mask = ptr + p.cq_off.ring_mask;
 399         cring->ring_entries = ptr + p.cq_off.ring_entries;
 400         cring->events = ptr + p.cq_off.elems;
 401         cq_ring_mask = *cring->ring_mask;
 402         return 0;
 403 }
 404
 405 int main(int argc, char *argv[])
 406 {
 407         struct submitter *s = &submitters[0];
 408         unsigned long done, calls, reap, cache_hit, cache_miss;
 409         int err, i;
 410         struct rlimit rlim;
 411         void *ret;
 412
 413         if (argc < 2) {
 414                 printf("%s: filename\n", argv[0]);
 415                 return 1;
 416         }
 417
 418         rlim.rlim_cur = RLIM_INFINITY;
 419         rlim.rlim_max = RLIM_INFINITY;
 420         if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
 421                 perror("setrlimit");
 422                 return 1;
 423         }
 424
 425         arm_sig_int();
 426
 427         for (i = 0; i < DEPTH; i++) {
 428                 void *buf;
 429
 430                 if (posix_memalign(&buf, BS, BS)) {
 431                         printf("failed alloc\n");
 432                         return 1;
 433                 }
 434                 s->iovecs[i].iov_base = buf;
 435                 s->iovecs[i].iov_len = BS;
 436         }
 437
 438         err = setup_ring(s);
 439         if (err) {
 440                 printf("ring setup failed: %s, %d\n", strerror(errno), err);
 441                 return 1;
 442         }
 443         printf("polled=%d, fixedbufs=%d, buffered=%d", polled, fixedbufs, buffered);
 444         printf(" QD=%d, sq_ring=%d, cq_ring=%d\n", DEPTH, *s->sq_ring.ring_entries, *s->cq_ring.ring_entries);
 445         strcpy(s->filename, argv[1]);
 446
 447         pthread_create(&s->thread, NULL, submitter_fn, s);
 448
 449         cache_hit = cache_miss = reap = calls = done = 0;
 450         do {
 451                 unsigned long this_done = 0;
 452                 unsigned long this_reap = 0;
 453                 unsigned long this_call = 0;
 454                 unsigned long this_cache_hit = 0;
 455                 unsigned long this_cache_miss = 0;
 456                 unsigned long rpc = 0, ipc = 0;
 457                 double hit = 0.0;
 458
 459                 sleep(1);
 460                 this_done += s->done;
 461                 this_call += s->calls;
 462                 this_reap += s->reaps;
 463                 this_cache_hit += s->cachehit;
 464                 this_cache_miss += s->cachemiss;
 465                 if (this_cache_hit && this_cache_miss) {
 466                         unsigned long hits, total;
 467
 468                         hits = this_cache_hit - cache_hit;
 469                         total = hits + this_cache_miss - cache_miss;
 470                         hit = (double) hits / (double) total;
 471                         hit *= 100.0;
 472                 }
 473                 if (this_call - calls) {
 474                         rpc = (this_done - done) / (this_call - calls);
 475                         ipc = (this_reap - reap) / (this_call - calls);
 476                 }
 477                 printf("IOPS=%lu, IOS/call=%lu/%lu, inflight=%u (head=%u tail=%u), Cachehit=%0.2f%%\n",
 478                                 this_done - done, rpc, ipc, s->inflight,
 479                                 *s->cq_ring.head, *s->cq_ring.tail, hit);
 480                 done = this_done;
 481                 calls = this_call;
 482                 reap = this_reap;
 483                 cache_hit = s->cachehit;
 484                 cache_miss = s->cachemiss;
 485         } while (!finish);
 486
 487         pthread_join(s->thread, &ret);
 488         return 0;
 489 }