Rename t/aio-ring to t/io_uring
authorJens Axboe <axboe@kernel.dk>
Tue, 8 Jan 2019 04:35:15 +0000 (21:35 -0700)
committerJens Axboe <axboe@kernel.dk>
Tue, 8 Jan 2019 04:35:15 +0000 (21:35 -0700)
The new API is completely discoupled from the aio/libaio
interface. Rename it while adopting the new API.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Makefile
os/io_uring.h [new file with mode: 0644]
t/aio-ring.c [deleted file]
t/io_uring.c [new file with mode: 0644]

index f111ae6..9492da6 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -266,8 +266,8 @@ T_VS_PROGS = t/fio-verify-state
 T_PIPE_ASYNC_OBJS = t/read-to-pipe-async.o
 T_PIPE_ASYNC_PROGS = t/read-to-pipe-async
 
-T_AIO_RING_OBJS = t/aio-ring.o
-T_AIO_RING_PROGS = t/aio-ring
+T_IOU_RING_OBJS = t/io_uring.o
+T_IOU_RING_PROGS = t/io_uring
 
 T_MEMLOCK_OBJS = t/memlock.o
 T_MEMLOCK_PROGS = t/memlock
@@ -287,7 +287,7 @@ T_OBJS += $(T_VS_OBJS)
 T_OBJS += $(T_PIPE_ASYNC_OBJS)
 T_OBJS += $(T_MEMLOCK_OBJS)
 T_OBJS += $(T_TT_OBJS)
-T_OBJS += $(T_AIO_RING_OBJS)
+T_OBJS += $(T_IOU_RING_OBJS)
 
 ifneq (,$(findstring CYGWIN,$(CONFIG_TARGET_OS)))
     T_DEDUPE_OBJS += os/windows/posix.o lib/hweight.o
@@ -447,8 +447,8 @@ cairo_text_helpers.o: cairo_text_helpers.c cairo_text_helpers.h
 printing.o: printing.c printing.h
        $(QUIET_CC)$(CC) $(CFLAGS) $(GTK_CFLAGS) $(CPPFLAGS) -c $<
 
-t/aio-ring: $(T_AIO_RING_OBJS)
-       $(QUIET_LINK)$(CC) $(LDFLAGS) $(CFLAGS) -o $@ $(T_AIO_RING_OBJS) $(LIBS)
+t/io_uring: $(T_IOU_RING_OBJS)
+       $(QUIET_LINK)$(CC) $(LDFLAGS) $(CFLAGS) -o $@ $(T_IOU_RING_OBJS) $(LIBS)
 
 t/read-to-pipe-async: $(T_PIPE_ASYNC_OBJS)
        $(QUIET_LINK)$(CC) $(LDFLAGS) $(CFLAGS) -o $@ $(T_PIPE_ASYNC_OBJS) $(LIBS)
diff --git a/os/io_uring.h b/os/io_uring.h
new file mode 100644 (file)
index 0000000..61a3753
--- /dev/null
@@ -0,0 +1,99 @@
+#ifndef IO_URING_H
+#define IO_URING_H
+
+/*
+ * IO submission data structure
+ */
+struct io_uring_iocb {
+       u8      opcode;
+       u8      flags;
+       u16     ioprio;
+       s32     fd;
+       u64     off;
+       union {
+               void    *addr;
+               u64     __pad;
+       };
+       u32     len;
+       union {
+               __kernel_rwf_t  rw_flags;
+               u32             __resv;
+       };
+};
+
+/*
+ * io_uring_setup() flags
+ */
+#define IORING_SETUP_IOPOLL    (1 << 0)        /* io_context is polled */
+#define IORING_SETUP_FIXEDBUFS (1 << 1)        /* IO buffers are fixed */
+#define IORING_SETUP_SQTHREAD  (1 << 2)        /* Use SQ thread */
+#define IORING_SETUP_SQWQ      (1 << 3)        /* Use SQ workqueue */
+#define IORING_SETUP_SQPOLL    (1 << 4)        /* SQ thread polls */
+
+#define IORING_OP_READ         1
+#define IORING_OP_WRITE                2
+#define IORING_OP_FSYNC                3
+#define IORING_OP_FDSYNC       4
+#define IORING_OP_READ_FIXED   5
+#define IORING_OP_WRITE_FIXED  6
+
+/*
+ * IO completion data structure
+ */
+struct io_uring_event {
+       __u64   index;          /* what iocb this event came from */
+       s32     res;            /* result code for this event */
+       u32     flags;
+};
+
+#define IOEV_FLAG_CACHEHIT     (1 << 0)        /* IO did not hit media */
+
+/*
+ * Magic offsets for the application to mmap the data it needs
+ */
+#define IORING_OFF_SQ_RING             0ULL
+#define IORING_OFF_CQ_RING             0x8000000ULL
+#define IORING_OFF_IOCB                        0x10000000ULL
+
+/*
+ * Filled with the offset for mmap(2)
+ */
+struct io_sqring_offsets {
+       u32 head;
+       u32 tail;
+       u32 ring_mask;
+       u32 ring_entries;
+       u32 flags;
+       u32 dropped;
+       u32 array;
+       u32 resv[3];
+};
+
+#define IORING_SQ_NEED_WAKEUP  (1 << 0) /* needs io_uring_enter wakeup */
+
+struct io_cqring_offsets {
+       u32 head;
+       u32 tail;
+       u32 ring_mask;
+       u32 ring_entries;
+       u32 overflow;
+       u32 events;
+       u32 resv[4];
+};
+
+#define IORING_ENTER_GETEVENTS (1 << 0)
+
+/*
+ * Passed in for io_uring_setup(2). Copied back with updated info on success
+ */
+struct io_uring_params {
+       u32 sq_entries;
+       u32 cq_entries;
+       u32 flags;
+       u16 sq_thread_cpu;
+       u16 resv[9];
+       struct io_sqring_offsets sq_off;
+       struct io_cqring_offsets cq_off;
+};
+
+#endif
diff --git a/t/aio-ring.c b/t/aio-ring.c
deleted file mode 100644 (file)
index 1a4fe44..0000000
+++ /dev/null
@@ -1,505 +0,0 @@
-/*
- * gcc -D_GNU_SOURCE -Wall -O2 -o aio-ring aio-ring.c  -lpthread -laio
- */
-#include <stdio.h>
-#include <errno.h>
-#include <assert.h>
-#include <stdlib.h>
-#include <stddef.h>
-#include <signal.h>
-#include <inttypes.h>
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/ioctl.h>
-#include <sys/syscall.h>
-#include <sys/resource.h>
-#include <sys/mman.h>
-#include <linux/fs.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <libaio.h>
-#include <string.h>
-#include <pthread.h>
-#include <sched.h>
-
-#include "../arch/arch.h"
-
-#define IOCTX_FLAG_SCQRING     (1 << 0)        /* Use SQ/CQ rings */
-#define IOCTX_FLAG_IOPOLL      (1 << 1)
-#define IOCTX_FLAG_FIXEDBUFS   (1 << 2)
-#define IOCTX_FLAG_SQTHREAD    (1 << 3)        /* Use SQ thread */
-#define IOCTX_FLAG_SQWQ                (1 << 4)        /* Use SQ wq */
-#define IOCTX_FLAG_SQPOLL      (1 << 5)
-
-#define IOEV_RES2_CACHEHIT     (1 << 0)
-
-#define barrier()      __asm__ __volatile__("": : :"memory")
-
-#define min(a, b)              ((a < b) ? (a) : (b))
-
-typedef uint64_t u64;
-typedef uint32_t u32;
-typedef uint16_t u16;
-
-#define IORING_OFF_SQ_RING     0ULL
-#define IORING_OFF_CQ_RING     0x8000000ULL
-#define IORING_OFF_IOCB                0x10000000ULL
-
-struct aio_sqring_offsets {
-       u32 head;
-       u32 tail;
-       u32 ring_mask;
-       u32 ring_entries;
-       u32 flags;
-       u32 dropped;
-       u32 array;
-       u32 resv[3];
-};
-
-struct aio_cqring_offsets {
-       u32 head;
-       u32 tail;
-       u32 ring_mask;
-       u32 ring_entries;
-       u32 overflow;
-       u32 events;
-       u32 resv[4];
-};
-
-struct aio_uring_params {
-       u32 sq_entries;
-       u32 cq_entries;
-       u32 flags;
-       u16 sq_thread_cpu;
-       u16 resv[9];
-       struct aio_sqring_offsets sq_off;
-       struct aio_cqring_offsets cq_off;
-};
-
-struct aio_sq_ring {
-       u32 *head;
-       u32 *tail;
-       u32 *ring_mask;
-       u32 *ring_entries;
-       u32 *array;
-};
-
-struct aio_cq_ring {
-       u32 *head;
-       u32 *tail;
-       u32 *ring_mask;
-       u32 *ring_entries;
-       struct io_event *events;
-};
-
-#define IORING_ENTER_GETEVENTS (1 << 0)
-
-#define DEPTH                  32
-
-#define BATCH_SUBMIT           8
-#define BATCH_COMPLETE         8
-
-#define BS                     4096
-
-static unsigned sq_ring_mask, cq_ring_mask;
-
-struct submitter {
-       pthread_t thread;
-       unsigned long max_blocks;
-       int ring_fd;
-       struct drand48_data rand;
-       struct aio_sq_ring sq_ring;
-       struct iocb *iocbs;
-       struct iovec iovecs[DEPTH];
-       struct aio_cq_ring cq_ring;
-       int inflight;
-       unsigned long reaps;
-       unsigned long done;
-       unsigned long calls;
-       unsigned long cachehit, cachemiss;
-       volatile int finish;
-       char filename[128];
-};
-
-static struct submitter submitters[1];
-static volatile int finish;
-
-static int polled = 0;         /* use IO polling */
-static int fixedbufs = 0;      /* use fixed user buffers */
-static int buffered = 1;       /* use buffered IO, not O_DIRECT */
-static int sq_thread = 0;      /* use kernel submission thread */
-static int sq_thread_cpu = 0;  /* pin above thread to this CPU */
-
-static int io_uring_setup(unsigned entries, struct iovec *iovecs,
-                         struct aio_uring_params *p)
-{
-       return syscall(__NR_sys_io_uring_setup, entries, iovecs, p);
-}
-
-static int io_uring_enter(struct submitter *s, unsigned int to_submit,
-                         unsigned int min_complete, unsigned int flags)
-{
-       return syscall(__NR_sys_io_uring_enter, s->ring_fd, to_submit,
-                       min_complete, flags);
-}
-
-static int gettid(void)
-{
-       return syscall(__NR_gettid);
-}
-
-static void init_io(struct submitter *s, int fd, unsigned index)
-{
-       struct iocb *iocb = &s->iocbs[index];
-       unsigned long offset;
-       long r;
-
-       lrand48_r(&s->rand, &r);
-       offset = (r % (s->max_blocks - 1)) * BS;
-
-       iocb->aio_fildes = fd;
-       iocb->aio_lio_opcode = IO_CMD_PREAD;
-       iocb->u.c.buf = s->iovecs[index].iov_base;
-       iocb->u.c.nbytes = BS;
-       iocb->u.c.offset = offset;
-}
-
-static int prep_more_ios(struct submitter *s, int fd, int max_ios)
-{
-       struct aio_sq_ring *ring = &s->sq_ring;
-       u32 index, tail, next_tail, prepped = 0;
-
-       next_tail = tail = *ring->tail;
-       do {
-               next_tail++;
-               barrier();
-               if (next_tail == *ring->head)
-                       break;
-
-               index = tail & sq_ring_mask;
-               init_io(s, fd, index);
-               ring->array[index] = index;
-               prepped++;
-               tail = next_tail;
-       } while (prepped < max_ios);
-
-       if (*ring->tail != tail) {
-               /* order tail store with writes to iocbs above */
-               barrier();
-               *ring->tail = tail;
-               barrier();
-       }
-       return prepped;
-}
-
-static int get_file_size(int fd, unsigned long *blocks)
-{
-       struct stat st;
-
-       if (fstat(fd, &st) < 0)
-               return -1;
-       if (S_ISBLK(st.st_mode)) {
-               unsigned long long bytes;
-
-               if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
-                       return -1;
-
-               *blocks = bytes / BS;
-               return 0;
-       } else if (S_ISREG(st.st_mode)) {
-               *blocks = st.st_size / BS;
-               return 0;
-       }
-
-       return -1;
-}
-
-static int reap_events(struct submitter *s)
-{
-       struct aio_cq_ring *ring = &s->cq_ring;
-       struct io_event *ev;
-       u32 head, reaped = 0;
-
-       head = *ring->head;
-       do {
-               barrier();
-               if (head == *ring->tail)
-                       break;
-               ev = &ring->events[head & cq_ring_mask];
-               if (ev->res != BS) {
-                       struct iocb *iocb = ev->obj;
-
-                       printf("io: unexpected ret=%ld\n", ev->res);
-                       printf("offset=%lu, size=%lu\n",
-                                       (unsigned long) iocb->u.c.offset,
-                                       (unsigned long) iocb->u.c.nbytes);
-                       return -1;
-               }
-               if (ev->res2 & IOEV_RES2_CACHEHIT)
-                       s->cachehit++;
-               else
-                       s->cachemiss++;
-               reaped++;
-               head++;
-       } while (1);
-
-       s->inflight -= reaped;
-       *ring->head = head;
-       barrier();
-       return reaped;
-}
-
-static void *submitter_fn(void *data)
-{
-       struct submitter *s = data;
-       int fd, ret, prepped, flags;
-
-       printf("submitter=%d\n", gettid());
-
-       flags = O_RDONLY;
-       if (!buffered)
-               flags |= O_DIRECT;
-       fd = open(s->filename, flags);
-       if (fd < 0) {
-               perror("open");
-               goto done;
-       }
-
-       if (get_file_size(fd, &s->max_blocks)) {
-               printf("failed getting size of device/file\n");
-               goto err;
-       }
-       if (s->max_blocks <= 1) {
-               printf("Zero file/device size?\n");
-               goto err;
-       }
-       s->max_blocks--;
-
-       srand48_r(pthread_self(), &s->rand);
-
-       prepped = 0;
-       do {
-               int to_wait, to_submit, this_reap, to_prep;
-
-               if (!prepped && s->inflight < DEPTH) {
-                       to_prep = min(DEPTH - s->inflight, BATCH_SUBMIT);
-                       prepped = prep_more_ios(s, fd, to_prep);
-               }
-               s->inflight += prepped;
-submit_more:
-               to_submit = prepped;
-submit:
-               if (s->inflight + BATCH_SUBMIT < DEPTH)
-                       to_wait = 0;
-               else
-                       to_wait = min(s->inflight + to_submit, BATCH_COMPLETE);
-
-               ret = io_uring_enter(s, to_submit, to_wait,
-                                       IORING_ENTER_GETEVENTS);
-               s->calls++;
-
-               this_reap = reap_events(s);
-               if (this_reap == -1)
-                       break;
-               s->reaps += this_reap;
-
-               if (ret >= 0) {
-                       if (!ret) {
-                               to_submit = 0;
-                               if (s->inflight)
-                                       goto submit;
-                               continue;
-                       } else if (ret < to_submit) {
-                               int diff = to_submit - ret;
-
-                               s->done += ret;
-                               prepped -= diff;
-                               goto submit_more;
-                       }
-                       s->done += ret;
-                       prepped = 0;
-                       continue;
-               } else if (ret < 0) {
-                       if (errno == EAGAIN) {
-                               if (s->finish)
-                                       break;
-                               if (this_reap)
-                                       goto submit;
-                               to_submit = 0;
-                               goto submit;
-                       }
-                       printf("io_submit: %s\n", strerror(errno));
-                       break;
-               }
-       } while (!s->finish);
-err:
-       close(fd);
-done:
-       finish = 1;
-       return NULL;
-}
-
-static void sig_int(int sig)
-{
-       printf("Exiting on signal %d\n", sig);
-       submitters[0].finish = 1;
-       finish = 1;
-}
-
-static void arm_sig_int(void)
-{
-       struct sigaction act;
-
-       memset(&act, 0, sizeof(act));
-       act.sa_handler = sig_int;
-       act.sa_flags = SA_RESTART;
-       sigaction(SIGINT, &act, NULL);
-}
-
-static int setup_ring(struct submitter *s)
-{
-       struct aio_sq_ring *sring = &s->sq_ring;
-       struct aio_cq_ring *cring = &s->cq_ring;
-       struct aio_uring_params p;
-       void *ptr;
-       int fd;
-
-       memset(&p, 0, sizeof(p));
-
-       p.flags = IOCTX_FLAG_SCQRING;
-       if (polled)
-               p.flags |= IOCTX_FLAG_IOPOLL;
-       if (fixedbufs)
-               p.flags |= IOCTX_FLAG_FIXEDBUFS;
-       if (buffered)
-               p.flags |= IOCTX_FLAG_SQWQ;
-       else if (sq_thread) {
-               p.flags |= IOCTX_FLAG_SQTHREAD;
-               p.sq_thread_cpu = sq_thread_cpu;
-       }
-
-       if (fixedbufs)
-               fd = io_uring_setup(DEPTH, s->iovecs, &p);
-       else
-               fd = io_uring_setup(DEPTH, NULL, &p);
-       if (fd < 0) {
-               perror("io_uring_setup");
-               return 1;
-       }
-
-       s->ring_fd = fd;
-       ptr = mmap(0, p.sq_off.array + p.sq_entries * sizeof(u32),
-                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
-                       IORING_OFF_SQ_RING);
-       printf("sq_ring ptr = 0x%p\n", ptr);
-       sring->head = ptr + p.sq_off.head;
-       sring->tail = ptr + p.sq_off.tail;
-       sring->ring_mask = ptr + p.sq_off.ring_mask;
-       sring->ring_entries = ptr + p.sq_off.ring_entries;
-       sring->array = ptr + p.sq_off.array;
-       sq_ring_mask = *sring->ring_mask;
-
-       s->iocbs = mmap(0, p.sq_entries * sizeof(struct iocb),
-                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
-                       IORING_OFF_IOCB);
-       printf("iocbs ptr   = 0x%p\n", s->iocbs);
-
-       ptr = mmap(0, p.cq_off.events + p.cq_entries * sizeof(struct io_event),
-                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
-                       IORING_OFF_CQ_RING);
-       printf("cq_ring ptr = 0x%p\n", ptr);
-       cring->head = ptr + p.cq_off.head;
-       cring->tail = ptr + p.cq_off.tail;
-       cring->ring_mask = ptr + p.cq_off.ring_mask;
-       cring->ring_entries = ptr + p.cq_off.ring_entries;
-       cring->events = ptr + p.cq_off.events;
-       cq_ring_mask = *cring->ring_mask;
-       return 0;
-}
-
-int main(int argc, char *argv[])
-{
-       struct submitter *s = &submitters[0];
-       unsigned long done, calls, reap, cache_hit, cache_miss;
-       int err, i;
-       struct rlimit rlim;
-       void *ret;
-
-       if (argc < 2) {
-               printf("%s: filename\n", argv[0]);
-               return 1;
-       }
-
-       rlim.rlim_cur = RLIM_INFINITY;
-       rlim.rlim_max = RLIM_INFINITY;
-       if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
-               perror("setrlimit");
-               return 1;
-       }
-
-       arm_sig_int();
-
-       for (i = 0; i < DEPTH; i++) {
-               void *buf;
-
-               if (posix_memalign(&buf, BS, BS)) {
-                       printf("failed alloc\n");
-                       return 1;
-               }
-               s->iovecs[i].iov_base = buf;
-               s->iovecs[i].iov_len = BS;
-       }
-
-       err = setup_ring(s);
-       if (err) {
-               printf("ring setup failed: %s, %d\n", strerror(errno), err);
-               return 1;
-       }
-       printf("polled=%d, fixedbufs=%d, buffered=%d", polled, fixedbufs, buffered);
-       printf(" QD=%d, sq_ring=%d, cq_ring=%d\n", DEPTH, *s->sq_ring.ring_entries, *s->cq_ring.ring_entries);
-       strcpy(s->filename, argv[1]);
-
-       pthread_create(&s->thread, NULL, submitter_fn, s);
-
-       cache_hit = cache_miss = reap = calls = done = 0;
-       do {
-               unsigned long this_done = 0;
-               unsigned long this_reap = 0;
-               unsigned long this_call = 0;
-               unsigned long this_cache_hit = 0;
-               unsigned long this_cache_miss = 0;
-               unsigned long rpc = 0, ipc = 0;
-               double hit = 0.0;
-
-               sleep(1);
-               this_done += s->done;
-               this_call += s->calls;
-               this_reap += s->reaps;
-               this_cache_hit += s->cachehit;
-               this_cache_miss += s->cachemiss;
-               if (this_cache_hit && this_cache_miss) {
-                       unsigned long hits, total;
-
-                       hits = this_cache_hit - cache_hit;
-                       total = hits + this_cache_miss - cache_miss;
-                       hit = (double) hits / (double) total;
-                       hit *= 100.0;
-               }
-               if (this_call - calls) {
-                       rpc = (this_done - done) / (this_call - calls);
-                       ipc = (this_reap - reap) / (this_call - calls);
-               }
-               printf("IOPS=%lu, IOS/call=%lu/%lu, inflight=%u (head=%u tail=%u), Cachehit=%0.2f%%\n",
-                               this_done - done, rpc, ipc, s->inflight,
-                               *s->cq_ring.head, *s->cq_ring.tail, hit);
-               done = this_done;
-               calls = this_call;
-               reap = this_reap;
-               cache_hit = s->cachehit;
-               cache_miss = s->cachemiss;
-       } while (!finish);
-
-       pthread_join(s->thread, &ret);
-       return 0;
-}
diff --git a/t/io_uring.c b/t/io_uring.c
new file mode 100644 (file)
index 0000000..83d723f
--- /dev/null
@@ -0,0 +1,462 @@
+#include <stdio.h>
+#include <errno.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <signal.h>
+#include <inttypes.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <sys/resource.h>
+#include <sys/mman.h>
+#include <sys/uio.h>
+#include <linux/fs.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+#include <sched.h>
+
+#include "../arch/arch.h"
+
+typedef uint64_t u64;
+typedef uint32_t u32;
+typedef int32_t s32;
+typedef uint16_t u16;
+typedef uint8_t u8;
+
+#include "../os/io_uring.h"
+
+#define barrier()      __asm__ __volatile__("": : :"memory")
+
+#define min(a, b)              ((a < b) ? (a) : (b))
+
+struct io_sq_ring {
+       u32 *head;
+       u32 *tail;
+       u32 *ring_mask;
+       u32 *ring_entries;
+       u32 *array;
+};
+
+struct io_cq_ring {
+       u32 *head;
+       u32 *tail;
+       u32 *ring_mask;
+       u32 *ring_entries;
+       struct io_uring_event *events;
+};
+
+#define DEPTH                  32
+
+#define BATCH_SUBMIT           8
+#define BATCH_COMPLETE         8
+
+#define BS                     4096
+
+static unsigned sq_ring_mask, cq_ring_mask;
+
+struct submitter {
+       pthread_t thread;
+       unsigned long max_blocks;
+       int ring_fd;
+       struct drand48_data rand;
+       struct io_sq_ring sq_ring;
+       struct io_uring_iocb *iocbs;
+       struct iovec iovecs[DEPTH];
+       struct io_cq_ring cq_ring;
+       int inflight;
+       unsigned long reaps;
+       unsigned long done;
+       unsigned long calls;
+       unsigned long cachehit, cachemiss;
+       volatile int finish;
+       char filename[128];
+};
+
+static struct submitter submitters[1];
+static volatile int finish;
+
+static int polled = 0;         /* use IO polling */
+static int fixedbufs = 0;      /* use fixed user buffers */
+static int buffered = 1;       /* use buffered IO, not O_DIRECT */
+static int sq_thread = 0;      /* use kernel submission thread */
+static int sq_thread_cpu = 0;  /* pin above thread to this CPU */
+
+static int io_uring_setup(unsigned entries, struct iovec *iovecs,
+                         struct io_uring_params *p)
+{
+       return syscall(__NR_sys_io_uring_setup, entries, iovecs, p);
+}
+
+static int io_uring_enter(struct submitter *s, unsigned int to_submit,
+                         unsigned int min_complete, unsigned int flags)
+{
+       return syscall(__NR_sys_io_uring_enter, s->ring_fd, to_submit,
+                       min_complete, flags);
+}
+
+static int gettid(void)
+{
+       return syscall(__NR_gettid);
+}
+
+static void init_io(struct submitter *s, int fd, unsigned index)
+{
+       struct io_uring_iocb *iocb = &s->iocbs[index];
+       unsigned long offset;
+       long r;
+
+       lrand48_r(&s->rand, &r);
+       offset = (r % (s->max_blocks - 1)) * BS;
+
+       iocb->opcode = IORING_OP_READ;
+       iocb->flags = 0;
+       iocb->ioprio = 0;
+       iocb->fd = fd;
+       iocb->off = offset;
+       iocb->addr = s->iovecs[index].iov_base;
+       iocb->len = BS;
+}
+
+static int prep_more_ios(struct submitter *s, int fd, int max_ios)
+{
+       struct io_sq_ring *ring = &s->sq_ring;
+       u32 index, tail, next_tail, prepped = 0;
+
+       next_tail = tail = *ring->tail;
+       do {
+               next_tail++;
+               barrier();
+               if (next_tail == *ring->head)
+                       break;
+
+               index = tail & sq_ring_mask;
+               init_io(s, fd, index);
+               ring->array[index] = index;
+               prepped++;
+               tail = next_tail;
+       } while (prepped < max_ios);
+
+       if (*ring->tail != tail) {
+               /* order tail store with writes to iocbs above */
+               barrier();
+               *ring->tail = tail;
+               barrier();
+       }
+       return prepped;
+}
+
+static int get_file_size(int fd, unsigned long *blocks)
+{
+       struct stat st;
+
+       if (fstat(fd, &st) < 0)
+               return -1;
+       if (S_ISBLK(st.st_mode)) {
+               unsigned long long bytes;
+
+               if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
+                       return -1;
+
+               *blocks = bytes / BS;
+               return 0;
+       } else if (S_ISREG(st.st_mode)) {
+               *blocks = st.st_size / BS;
+               return 0;
+       }
+
+       return -1;
+}
+
+static int reap_events(struct submitter *s)
+{
+       struct io_cq_ring *ring = &s->cq_ring;
+       struct io_uring_event *ev;
+       u32 head, reaped = 0;
+
+       head = *ring->head;
+       do {
+               barrier();
+               if (head == *ring->tail)
+                       break;
+               ev = &ring->events[head & cq_ring_mask];
+               if (ev->res != BS) {
+                       struct io_uring_iocb *iocb = &s->iocbs[ev->index];
+
+                       printf("io: unexpected ret=%d\n", ev->res);
+                       printf("offset=%lu, size=%lu\n",
+                                       (unsigned long) iocb->off,
+                                       (unsigned long) iocb->len);
+                       return -1;
+               }
+               if (ev->flags & IOEV_FLAG_CACHEHIT)
+                       s->cachehit++;
+               else
+                       s->cachemiss++;
+               reaped++;
+               head++;
+       } while (1);
+
+       s->inflight -= reaped;
+       *ring->head = head;
+       barrier();
+       return reaped;
+}
+
+static void *submitter_fn(void *data)
+{
+       struct submitter *s = data;
+       int fd, ret, prepped, flags;
+
+       printf("submitter=%d\n", gettid());
+
+       flags = O_RDONLY;
+       if (!buffered)
+               flags |= O_DIRECT;
+       fd = open(s->filename, flags);
+       if (fd < 0) {
+               perror("open");
+               goto done;
+       }
+
+       if (get_file_size(fd, &s->max_blocks)) {
+               printf("failed getting size of device/file\n");
+               goto err;
+       }
+       if (s->max_blocks <= 1) {
+               printf("Zero file/device size?\n");
+               goto err;
+       }
+       s->max_blocks--;
+
+       srand48_r(pthread_self(), &s->rand);
+
+       prepped = 0;
+       do {
+               int to_wait, to_submit, this_reap, to_prep;
+
+               if (!prepped && s->inflight < DEPTH) {
+                       to_prep = min(DEPTH - s->inflight, BATCH_SUBMIT);
+                       prepped = prep_more_ios(s, fd, to_prep);
+               }
+               s->inflight += prepped;
+submit_more:
+               to_submit = prepped;
+submit:
+               if (s->inflight + BATCH_SUBMIT < DEPTH)
+                       to_wait = 0;
+               else
+                       to_wait = min(s->inflight + to_submit, BATCH_COMPLETE);
+
+               ret = io_uring_enter(s, to_submit, to_wait,
+                                       IORING_ENTER_GETEVENTS);
+               s->calls++;
+
+               this_reap = reap_events(s);
+               if (this_reap == -1)
+                       break;
+               s->reaps += this_reap;
+
+               if (ret >= 0) {
+                       if (!ret) {
+                               to_submit = 0;
+                               if (s->inflight)
+                                       goto submit;
+                               continue;
+                       } else if (ret < to_submit) {
+                               int diff = to_submit - ret;
+
+                               s->done += ret;
+                               prepped -= diff;
+                               goto submit_more;
+                       }
+                       s->done += ret;
+                       prepped = 0;
+                       continue;
+               } else if (ret < 0) {
+                       if (errno == EAGAIN) {
+                               if (s->finish)
+                                       break;
+                               if (this_reap)
+                                       goto submit;
+                               to_submit = 0;
+                               goto submit;
+                       }
+                       printf("io_submit: %s\n", strerror(errno));
+                       break;
+               }
+       } while (!s->finish);
+err:
+       close(fd);
+done:
+       finish = 1;
+       return NULL;
+}
+
+static void sig_int(int sig)
+{
+       printf("Exiting on signal %d\n", sig);
+       submitters[0].finish = 1;
+       finish = 1;
+}
+
+static void arm_sig_int(void)
+{
+       struct sigaction act;
+
+       memset(&act, 0, sizeof(act));
+       act.sa_handler = sig_int;
+       act.sa_flags = SA_RESTART;
+       sigaction(SIGINT, &act, NULL);
+}
+
+static int setup_ring(struct submitter *s)
+{
+       struct io_sq_ring *sring = &s->sq_ring;
+       struct io_cq_ring *cring = &s->cq_ring;
+       struct io_uring_params p;
+       void *ptr;
+       int fd;
+
+       memset(&p, 0, sizeof(p));
+
+       if (polled)
+               p.flags |= IORING_SETUP_IOPOLL;
+       if (fixedbufs)
+               p.flags |= IORING_SETUP_FIXEDBUFS;
+       if (buffered)
+               p.flags |= IORING_SETUP_SQWQ;
+       else if (sq_thread) {
+               p.flags |= IORING_SETUP_SQTHREAD;
+               p.sq_thread_cpu = sq_thread_cpu;
+       }
+
+       if (fixedbufs)
+               fd = io_uring_setup(DEPTH, s->iovecs, &p);
+       else
+               fd = io_uring_setup(DEPTH, NULL, &p);
+       if (fd < 0) {
+               perror("io_uring_setup");
+               return 1;
+       }
+
+       s->ring_fd = fd;
+       ptr = mmap(0, p.sq_off.array + p.sq_entries * sizeof(u32),
+                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                       IORING_OFF_SQ_RING);
+       printf("sq_ring ptr = 0x%p\n", ptr);
+       sring->head = ptr + p.sq_off.head;
+       sring->tail = ptr + p.sq_off.tail;
+       sring->ring_mask = ptr + p.sq_off.ring_mask;
+       sring->ring_entries = ptr + p.sq_off.ring_entries;
+       sring->array = ptr + p.sq_off.array;
+       sq_ring_mask = *sring->ring_mask;
+
+       s->iocbs = mmap(0, p.sq_entries * sizeof(struct io_uring_iocb),
+                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                       IORING_OFF_IOCB);
+       printf("iocbs ptr   = 0x%p\n", s->iocbs);
+
+       ptr = mmap(0, p.cq_off.events + p.cq_entries * sizeof(struct io_uring_event),
+                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                       IORING_OFF_CQ_RING);
+       printf("cq_ring ptr = 0x%p\n", ptr);
+       cring->head = ptr + p.cq_off.head;
+       cring->tail = ptr + p.cq_off.tail;
+       cring->ring_mask = ptr + p.cq_off.ring_mask;
+       cring->ring_entries = ptr + p.cq_off.ring_entries;
+       cring->events = ptr + p.cq_off.events;
+       cq_ring_mask = *cring->ring_mask;
+       return 0;
+}
+
+int main(int argc, char *argv[])
+{
+       struct submitter *s = &submitters[0];
+       unsigned long done, calls, reap, cache_hit, cache_miss;
+       int err, i;
+       struct rlimit rlim;
+       void *ret;
+
+       if (argc < 2) {
+               printf("%s: filename\n", argv[0]);
+               return 1;
+       }
+
+       rlim.rlim_cur = RLIM_INFINITY;
+       rlim.rlim_max = RLIM_INFINITY;
+       if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
+               perror("setrlimit");
+               return 1;
+       }
+
+       arm_sig_int();
+
+       for (i = 0; i < DEPTH; i++) {
+               void *buf;
+
+               if (posix_memalign(&buf, BS, BS)) {
+                       printf("failed alloc\n");
+                       return 1;
+               }
+               s->iovecs[i].iov_base = buf;
+               s->iovecs[i].iov_len = BS;
+       }
+
+       err = setup_ring(s);
+       if (err) {
+               printf("ring setup failed: %s, %d\n", strerror(errno), err);
+               return 1;
+       }
+       printf("polled=%d, fixedbufs=%d, buffered=%d", polled, fixedbufs, buffered);
+       printf(" QD=%d, sq_ring=%d, cq_ring=%d\n", DEPTH, *s->sq_ring.ring_entries, *s->cq_ring.ring_entries);
+       strcpy(s->filename, argv[1]);
+
+       pthread_create(&s->thread, NULL, submitter_fn, s);
+
+       cache_hit = cache_miss = reap = calls = done = 0;
+       do {
+               unsigned long this_done = 0;
+               unsigned long this_reap = 0;
+               unsigned long this_call = 0;
+               unsigned long this_cache_hit = 0;
+               unsigned long this_cache_miss = 0;
+               unsigned long rpc = 0, ipc = 0;
+               double hit = 0.0;
+
+               sleep(1);
+               this_done += s->done;
+               this_call += s->calls;
+               this_reap += s->reaps;
+               this_cache_hit += s->cachehit;
+               this_cache_miss += s->cachemiss;
+               if (this_cache_hit && this_cache_miss) {
+                       unsigned long hits, total;
+
+                       hits = this_cache_hit - cache_hit;
+                       total = hits + this_cache_miss - cache_miss;
+                       hit = (double) hits / (double) total;
+                       hit *= 100.0;
+               }
+               if (this_call - calls) {
+                       rpc = (this_done - done) / (this_call - calls);
+                       ipc = (this_reap - reap) / (this_call - calls);
+               }
+               printf("IOPS=%lu, IOS/call=%lu/%lu, inflight=%u (head=%u tail=%u), Cachehit=%0.2f%%\n",
+                               this_done - done, rpc, ipc, s->inflight,
+                               *s->cq_ring.head, *s->cq_ring.tail, hit);
+               done = this_done;
+               calls = this_call;
+               reap = this_reap;
+               cache_hit = s->cachehit;
+               cache_miss = s->cachemiss;
+       } while (!finish);
+
+       pthread_join(s->thread, &ret);
+       close(s->ring_fd);
+       return 0;
+}