io_uring: add a few test tools
authorJens Axboe <axboe@kernel.dk>
Wed, 6 Mar 2019 16:03:50 +0000 (09:03 -0700)
committerJens Axboe <axboe@kernel.dk>
Wed, 6 Mar 2019 20:00:16 +0000 (13:00 -0700)
This adds two test programs in tools/io_uring/ that demonstrate both
the raw io_uring API (and all features) through a small benchmark
app, io_uring-bench, and the liburing exposed API in a simplified
cp(1) implementation through io_uring-cp.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
tools/io_uring/Makefile [new file with mode: 0644]
tools/io_uring/README [new file with mode: 0644]
tools/io_uring/barrier.h [new file with mode: 0644]
tools/io_uring/io_uring-bench.c [new file with mode: 0644]
tools/io_uring/io_uring-cp.c [new file with mode: 0644]
tools/io_uring/liburing.h [new file with mode: 0644]
tools/io_uring/queue.c [new file with mode: 0644]
tools/io_uring/setup.c [new file with mode: 0644]
tools/io_uring/syscall.c [new file with mode: 0644]

diff --git a/tools/io_uring/Makefile b/tools/io_uring/Makefile
new file mode 100644 (file)
index 0000000..f79522f
--- /dev/null
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for io_uring test tools
+CFLAGS += -Wall -Wextra -g -D_GNU_SOURCE
+LDLIBS += -lpthread
+
+all: io_uring-cp io_uring-bench
+%: %.c
+       $(CC) $(CFLAGS) -o $@ $^
+
+io_uring-bench: syscall.o io_uring-bench.o
+       $(CC) $(CFLAGS) $(LDLIBS) -o $@ $^
+
+io_uring-cp: setup.o syscall.o queue.o
+
+clean:
+       $(RM) io_uring-cp io_uring-bench *.o
+
+.PHONY: all clean
diff --git a/tools/io_uring/README b/tools/io_uring/README
new file mode 100644 (file)
index 0000000..67fd701
--- /dev/null
@@ -0,0 +1,29 @@
+This directory includes a few programs that demonstrate how to use io_uring
+in an application. The examples are:
+
+io_uring-cp
+       A very basic io_uring implementation of cp(1). It takes two
+       arguments, copies the first argument to the second. This example
+       is part of liburing, and hence uses the simplified liburing API
+       for setting up an io_uring instance, submitting IO, completing IO,
+       etc. The support functions in queue.c and setup.c are straight
+       out of liburing.
+
+io_uring-bench
+       Benchmark program that does random reads on a number of files. This
+       app demonstrates the various features of io_uring, like fixed files,
+       fixed buffers, and polled IO. There are options in the program to
+       control which features to use. Arguments is the file (or files) that
+       io_uring-bench should operate on. This uses the raw io_uring
+       interface.
+
+liburing can be cloned with git here:
+
+       git://git.kernel.dk/liburing
+
+and contains a number of unit tests as well for testing io_uring. It also
+comes with man pages for the three system calls.
+
+Fio includes an io_uring engine, you can clone fio here:
+
+       git://git.kernel.dk/fio
diff --git a/tools/io_uring/barrier.h b/tools/io_uring/barrier.h
new file mode 100644 (file)
index 0000000..ef00f67
--- /dev/null
@@ -0,0 +1,16 @@
+#ifndef LIBURING_BARRIER_H
+#define LIBURING_BARRIER_H
+
+#if defined(__x86_64) || defined(__i386__)
+#define read_barrier() __asm__ __volatile__("":::"memory")
+#define write_barrier()        __asm__ __volatile__("":::"memory")
+#else
+/*
+ * Add arch appropriate definitions. Be safe and use full barriers for
+ * archs we don't have support for.
+ */
+#define read_barrier() __sync_synchronize()
+#define write_barrier()        __sync_synchronize()
+#endif
+
+#endif
diff --git a/tools/io_uring/io_uring-bench.c b/tools/io_uring/io_uring-bench.c
new file mode 100644 (file)
index 0000000..512306a
--- /dev/null
@@ -0,0 +1,616 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple benchmark program that uses the various features of io_uring
+ * to provide fast random access to a device/file. It has various
+ * options that are control how we use io_uring, see the OPTIONS section
+ * below. This uses the raw io_uring interface.
+ *
+ * Copyright (C) 2018-2019 Jens Axboe
+ */
+#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 "liburing.h"
+#include "barrier.h"
+
+#ifndef IOCQE_FLAG_CACHEHIT
+#define IOCQE_FLAG_CACHEHIT    (1U << 0)
+#endif
+
+#define min(a, b)              ((a < b) ? (a) : (b))
+
+struct io_sq_ring {
+       unsigned *head;
+       unsigned *tail;
+       unsigned *ring_mask;
+       unsigned *ring_entries;
+       unsigned *flags;
+       unsigned *array;
+};
+
+struct io_cq_ring {
+       unsigned *head;
+       unsigned *tail;
+       unsigned *ring_mask;
+       unsigned *ring_entries;
+       struct io_uring_cqe *cqes;
+};
+
+#define DEPTH                  128
+
+#define BATCH_SUBMIT           32
+#define BATCH_COMPLETE         32
+
+#define BS                     4096
+
+#define MAX_FDS                        16
+
+static unsigned sq_ring_mask, cq_ring_mask;
+
+struct file {
+       unsigned long max_blocks;
+       unsigned pending_ios;
+       int real_fd;
+       int fixed_fd;
+};
+
+struct submitter {
+       pthread_t thread;
+       int ring_fd;
+       struct drand48_data rand;
+       struct io_sq_ring sq_ring;
+       struct io_uring_sqe *sqes;
+       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;
+
+       __s32 *fds;
+
+       struct file files[MAX_FDS];
+       unsigned nr_files;
+       unsigned cur_file;
+};
+
+static struct submitter submitters[1];
+static volatile int finish;
+
+/*
+ * OPTIONS: Set these to test the various features of io_uring.
+ */
+static int polled = 1;         /* use IO polling */
+static int fixedbufs = 1;      /* use fixed user buffers */
+static int register_files = 1; /* use fixed files */
+static int buffered = 0;       /* use buffered IO, not O_DIRECT */
+static int sq_thread_poll = 0; /* use kernel submission/poller thread */
+static int sq_thread_cpu = -1; /* pin above thread to this CPU */
+static int do_nop = 0;         /* no-op SQ ring commands */
+
+static int io_uring_register_buffers(struct submitter *s)
+{
+       if (do_nop)
+               return 0;
+
+       return io_uring_register(s->ring_fd, IORING_REGISTER_BUFFERS, s->iovecs,
+                                       DEPTH);
+}
+
+static int io_uring_register_files(struct submitter *s)
+{
+       unsigned i;
+
+       if (do_nop)
+               return 0;
+
+       s->fds = calloc(s->nr_files, sizeof(__s32));
+       for (i = 0; i < s->nr_files; i++) {
+               s->fds[i] = s->files[i].real_fd;
+               s->files[i].fixed_fd = i;
+       }
+
+       return io_uring_register(s->ring_fd, IORING_REGISTER_FILES, s->fds,
+                                       s->nr_files);
+}
+
+static int gettid(void)
+{
+       return syscall(__NR_gettid);
+}
+
+static unsigned file_depth(struct submitter *s)
+{
+       return (DEPTH + s->nr_files - 1) / s->nr_files;
+}
+
+static void init_io(struct submitter *s, unsigned index)
+{
+       struct io_uring_sqe *sqe = &s->sqes[index];
+       unsigned long offset;
+       struct file *f;
+       long r;
+
+       if (do_nop) {
+               sqe->opcode = IORING_OP_NOP;
+               return;
+       }
+
+       if (s->nr_files == 1) {
+               f = &s->files[0];
+       } else {
+               f = &s->files[s->cur_file];
+               if (f->pending_ios >= file_depth(s)) {
+                       s->cur_file++;
+                       if (s->cur_file == s->nr_files)
+                               s->cur_file = 0;
+                       f = &s->files[s->cur_file];
+               }
+       }
+       f->pending_ios++;
+
+       lrand48_r(&s->rand, &r);
+       offset = (r % (f->max_blocks - 1)) * BS;
+
+       if (register_files) {
+               sqe->flags = IOSQE_FIXED_FILE;
+               sqe->fd = f->fixed_fd;
+       } else {
+               sqe->flags = 0;
+               sqe->fd = f->real_fd;
+       }
+       if (fixedbufs) {
+               sqe->opcode = IORING_OP_READ_FIXED;
+               sqe->addr = (unsigned long) s->iovecs[index].iov_base;
+               sqe->len = BS;
+               sqe->buf_index = index;
+       } else {
+               sqe->opcode = IORING_OP_READV;
+               sqe->addr = (unsigned long) &s->iovecs[index];
+               sqe->len = 1;
+               sqe->buf_index = 0;
+       }
+       sqe->ioprio = 0;
+       sqe->off = offset;
+       sqe->user_data = (unsigned long) f;
+}
+
+static int prep_more_ios(struct submitter *s, unsigned max_ios)
+{
+       struct io_sq_ring *ring = &s->sq_ring;
+       unsigned index, tail, next_tail, prepped = 0;
+
+       next_tail = tail = *ring->tail;
+       do {
+               next_tail++;
+               read_barrier();
+               if (next_tail == *ring->head)
+                       break;
+
+               index = tail & sq_ring_mask;
+               init_io(s, index);
+               ring->array[index] = index;
+               prepped++;
+               tail = next_tail;
+       } while (prepped < max_ios);
+
+       if (*ring->tail != tail) {
+               /* order tail store with writes to sqes above */
+               write_barrier();
+               *ring->tail = tail;
+               write_barrier();
+       }
+       return prepped;
+}
+
+static int get_file_size(struct file *f)
+{
+       struct stat st;
+
+       if (fstat(f->real_fd, &st) < 0)
+               return -1;
+       if (S_ISBLK(st.st_mode)) {
+               unsigned long long bytes;
+
+               if (ioctl(f->real_fd, BLKGETSIZE64, &bytes) != 0)
+                       return -1;
+
+               f->max_blocks = bytes / BS;
+               return 0;
+       } else if (S_ISREG(st.st_mode)) {
+               f->max_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_cqe *cqe;
+       unsigned head, reaped = 0;
+
+       head = *ring->head;
+       do {
+               struct file *f;
+
+               read_barrier();
+               if (head == *ring->tail)
+                       break;
+               cqe = &ring->cqes[head & cq_ring_mask];
+               if (!do_nop) {
+                       f = (struct file *) (uintptr_t) cqe->user_data;
+                       f->pending_ios--;
+                       if (cqe->res != BS) {
+                               printf("io: unexpected ret=%d\n", cqe->res);
+                               if (polled && cqe->res == -EOPNOTSUPP)
+                                       printf("Your filesystem doesn't support poll\n");
+                               return -1;
+                       }
+               }
+               if (cqe->flags & IOCQE_FLAG_CACHEHIT)
+                       s->cachehit++;
+               else
+                       s->cachemiss++;
+               reaped++;
+               head++;
+       } while (1);
+
+       s->inflight -= reaped;
+       *ring->head = head;
+       write_barrier();
+       return reaped;
+}
+
+static void *submitter_fn(void *data)
+{
+       struct submitter *s = data;
+       struct io_sq_ring *ring = &s->sq_ring;
+       int ret, prepped;
+
+       printf("submitter=%d\n", gettid());
+
+       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, to_prep);
+               }
+               s->inflight += prepped;
+submit_more:
+               to_submit = prepped;
+submit:
+               if (to_submit && (s->inflight + to_submit <= DEPTH))
+                       to_wait = 0;
+               else
+                       to_wait = min(s->inflight + to_submit, BATCH_COMPLETE);
+
+               /*
+                * Only need to call io_uring_enter if we're not using SQ thread
+                * poll, or if IORING_SQ_NEED_WAKEUP is set.
+                */
+               if (!sq_thread_poll || (*ring->flags & IORING_SQ_NEED_WAKEUP)) {
+                       unsigned flags = 0;
+
+                       if (to_wait)
+                               flags = IORING_ENTER_GETEVENTS;
+                       if ((*ring->flags & IORING_SQ_NEED_WAKEUP))
+                               flags |= IORING_ENTER_SQ_WAKEUP;
+                       ret = io_uring_enter(s->ring_fd, to_submit, to_wait,
+                                               flags, NULL);
+                       s->calls++;
+               }
+
+               /*
+                * For non SQ thread poll, we already got the events we needed
+                * through the io_uring_enter() above. For SQ thread poll, we
+                * need to loop here until we find enough events.
+                */
+               this_reap = 0;
+               do {
+                       int r;
+                       r = reap_events(s);
+                       if (r == -1) {
+                               s->finish = 1;
+                               break;
+                       } else if (r > 0)
+                               this_reap += r;
+               } while (sq_thread_poll && this_reap < to_wait);
+               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);
+
+       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;
+       int ret, fd;
+       void *ptr;
+
+       memset(&p, 0, sizeof(p));
+
+       if (polled && !do_nop)
+               p.flags |= IORING_SETUP_IOPOLL;
+       if (sq_thread_poll) {
+               p.flags |= IORING_SETUP_SQPOLL;
+               if (sq_thread_cpu != -1) {
+                       p.flags |= IORING_SETUP_SQ_AFF;
+                       p.sq_thread_cpu = sq_thread_cpu;
+               }
+       }
+
+       fd = io_uring_setup(DEPTH, &p);
+       if (fd < 0) {
+               perror("io_uring_setup");
+               return 1;
+       }
+       s->ring_fd = fd;
+
+       if (fixedbufs) {
+               ret = io_uring_register_buffers(s);
+               if (ret < 0) {
+                       perror("io_uring_register_buffers");
+                       return 1;
+               }
+       }
+
+       if (register_files) {
+               ret = io_uring_register_files(s);
+               if (ret < 0) {
+                       perror("io_uring_register_files");
+                       return 1;
+               }
+       }
+
+       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->flags = ptr + p.sq_off.flags;
+       sring->array = ptr + p.sq_off.array;
+       sq_ring_mask = *sring->ring_mask;
+
+       s->sqes = mmap(0, p.sq_entries * sizeof(struct io_uring_sqe),
+                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, fd,
+                       IORING_OFF_SQES);
+       printf("sqes ptr    = 0x%p\n", s->sqes);
+
+       ptr = mmap(0, p.cq_off.cqes + p.cq_entries * sizeof(struct io_uring_cqe),
+                       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->cqes = ptr + p.cq_off.cqes;
+       cq_ring_mask = *cring->ring_mask;
+       return 0;
+}
+
+static void file_depths(char *buf)
+{
+       struct submitter *s = &submitters[0];
+       unsigned i;
+       char *p;
+
+       buf[0] = '\0';
+       p = buf;
+       for (i = 0; i < s->nr_files; i++) {
+               struct file *f = &s->files[i];
+
+               if (i + 1 == s->nr_files)
+                       p += sprintf(p, "%d", f->pending_ios);
+               else
+                       p += sprintf(p, "%d, ", f->pending_ios);
+       }
+}
+
+int main(int argc, char *argv[])
+{
+       struct submitter *s = &submitters[0];
+       unsigned long done, calls, reap, cache_hit, cache_miss;
+       int err, i, flags, fd;
+       char *fdepths;
+       void *ret;
+
+       if (!do_nop && argc < 2) {
+               printf("%s: filename\n", argv[0]);
+               return 1;
+       }
+
+       flags = O_RDONLY | O_NOATIME;
+       if (!buffered)
+               flags |= O_DIRECT;
+
+       i = 1;
+       while (!do_nop && i < argc) {
+               struct file *f;
+
+               if (s->nr_files == MAX_FDS) {
+                       printf("Max number of files (%d) reached\n", MAX_FDS);
+                       break;
+               }
+               fd = open(argv[i], flags);
+               if (fd < 0) {
+                       perror("open");
+                       return 1;
+               }
+
+               f = &s->files[s->nr_files];
+               f->real_fd = fd;
+               if (get_file_size(f)) {
+                       printf("failed getting size of device/file\n");
+                       return 1;
+               }
+               if (f->max_blocks <= 1) {
+                       printf("Zero file/device size?\n");
+                       return 1;
+               }
+               f->max_blocks--;
+
+               printf("Added file %s\n", argv[i]);
+               s->nr_files++;
+               i++;
+       }
+
+       if (fixedbufs) {
+               struct rlimit rlim;
+
+               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);
+
+       pthread_create(&s->thread, NULL, submitter_fn, s);
+
+       fdepths = malloc(8 * s->nr_files);
+       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);
+               } else
+                       rpc = ipc = -1;
+               file_depths(fdepths);
+               printf("IOPS=%lu, IOS/call=%ld/%ld, inflight=%u (%s), Cachehit=%0.2f%%\n",
+                               this_done - done, rpc, ipc, s->inflight,
+                               fdepths, 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);
+       free(fdepths);
+       return 0;
+}
diff --git a/tools/io_uring/io_uring-cp.c b/tools/io_uring/io_uring-cp.c
new file mode 100644 (file)
index 0000000..633f65b
--- /dev/null
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple test program that demonstrates a file copy through io_uring. This
+ * uses the API exposed by liburing.
+ *
+ * Copyright (C) 2018-2019 Jens Axboe
+ */
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+
+#include "liburing.h"
+
+#define QD     64
+#define BS     (32*1024)
+
+static int infd, outfd;
+
+struct io_data {
+       int read;
+       off_t first_offset, offset;
+       size_t first_len;
+       struct iovec iov;
+};
+
+static int setup_context(unsigned entries, struct io_uring *ring)
+{
+       int ret;
+
+       ret = io_uring_queue_init(entries, ring, 0);
+       if (ret < 0) {
+               fprintf(stderr, "queue_init: %s\n", strerror(-ret));
+               return -1;
+       }
+
+       return 0;
+}
+
+static int get_file_size(int fd, off_t *size)
+{
+       struct stat st;
+
+       if (fstat(fd, &st) < 0)
+               return -1;
+       if (S_ISREG(st.st_mode)) {
+               *size = st.st_size;
+               return 0;
+       } else if (S_ISBLK(st.st_mode)) {
+               unsigned long long bytes;
+
+               if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
+                       return -1;
+
+               *size = bytes;
+               return 0;
+       }
+
+       return -1;
+}
+
+static void queue_prepped(struct io_uring *ring, struct io_data *data)
+{
+       struct io_uring_sqe *sqe;
+
+       sqe = io_uring_get_sqe(ring);
+       assert(sqe);
+
+       if (data->read)
+               io_uring_prep_readv(sqe, infd, &data->iov, 1, data->offset);
+       else
+               io_uring_prep_writev(sqe, outfd, &data->iov, 1, data->offset);
+
+       io_uring_sqe_set_data(sqe, data);
+}
+
+static int queue_read(struct io_uring *ring, off_t size, off_t offset)
+{
+       struct io_uring_sqe *sqe;
+       struct io_data *data;
+
+       sqe = io_uring_get_sqe(ring);
+       if (!sqe)
+               return 1;
+
+       data = malloc(size + sizeof(*data));
+       data->read = 1;
+       data->offset = data->first_offset = offset;
+
+       data->iov.iov_base = data + 1;
+       data->iov.iov_len = size;
+       data->first_len = size;
+
+       io_uring_prep_readv(sqe, infd, &data->iov, 1, offset);
+       io_uring_sqe_set_data(sqe, data);
+       return 0;
+}
+
+static void queue_write(struct io_uring *ring, struct io_data *data)
+{
+       data->read = 0;
+       data->offset = data->first_offset;
+
+       data->iov.iov_base = data + 1;
+       data->iov.iov_len = data->first_len;
+
+       queue_prepped(ring, data);
+       io_uring_submit(ring);
+}
+
+static int copy_file(struct io_uring *ring, off_t insize)
+{
+       unsigned long reads, writes;
+       struct io_uring_cqe *cqe;
+       off_t write_left, offset;
+       int ret;
+
+       write_left = insize;
+       writes = reads = offset = 0;
+
+       while (insize || write_left) {
+               unsigned long had_reads;
+               int got_comp;
+
+               /*
+                * Queue up as many reads as we can
+                */
+               had_reads = reads;
+               while (insize) {
+                       off_t this_size = insize;
+
+                       if (reads + writes >= QD)
+                               break;
+                       if (this_size > BS)
+                               this_size = BS;
+                       else if (!this_size)
+                               break;
+
+                       if (queue_read(ring, this_size, offset))
+                               break;
+
+                       insize -= this_size;
+                       offset += this_size;
+                       reads++;
+               }
+
+               if (had_reads != reads) {
+                       ret = io_uring_submit(ring);
+                       if (ret < 0) {
+                               fprintf(stderr, "io_uring_submit: %s\n", strerror(-ret));
+                               break;
+                       }
+               }
+
+               /*
+                * Queue is full at this point. Find at least one completion.
+                */
+               got_comp = 0;
+               while (write_left) {
+                       struct io_data *data;
+
+                       if (!got_comp) {
+                               ret = io_uring_wait_completion(ring, &cqe);
+                               got_comp = 1;
+                       } else
+                               ret = io_uring_get_completion(ring, &cqe);
+                       if (ret < 0) {
+                               fprintf(stderr, "io_uring_get_completion: %s\n",
+                                                       strerror(-ret));
+                               return 1;
+                       }
+                       if (!cqe)
+                               break;
+
+                       data = (struct io_data *) (uintptr_t) cqe->user_data;
+                       if (cqe->res < 0) {
+                               if (cqe->res == -EAGAIN) {
+                                       queue_prepped(ring, data);
+                                       continue;
+                               }
+                               fprintf(stderr, "cqe failed: %s\n",
+                                               strerror(-cqe->res));
+                               return 1;
+                       } else if ((size_t) cqe->res != data->iov.iov_len) {
+                               /* Short read/write, adjust and requeue */
+                               data->iov.iov_base += cqe->res;
+                               data->iov.iov_len -= cqe->res;
+                               data->offset += cqe->res;
+                               queue_prepped(ring, data);
+                               continue;
+                       }
+
+                       /*
+                        * All done. if write, nothing else to do. if read,
+                        * queue up corresponding write.
+                        */
+                       if (data->read) {
+                               queue_write(ring, data);
+                               write_left -= data->first_len;
+                               reads--;
+                               writes++;
+                       } else {
+                               free(data);
+                               writes--;
+                       }
+               }
+       }
+
+       return 0;
+}
+
+int main(int argc, char *argv[])
+{
+       struct io_uring ring;
+       off_t insize;
+       int ret;
+
+       if (argc < 3) {
+               printf("%s: infile outfile\n", argv[0]);
+               return 1;
+       }
+
+       infd = open(argv[1], O_RDONLY);
+       if (infd < 0) {
+               perror("open infile");
+               return 1;
+       }
+       outfd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+       if (outfd < 0) {
+               perror("open outfile");
+               return 1;
+       }
+
+       if (setup_context(QD, &ring))
+               return 1;
+       if (get_file_size(infd, &insize))
+               return 1;
+
+       ret = copy_file(&ring, insize);
+
+       close(infd);
+       close(outfd);
+       io_uring_queue_exit(&ring);
+       return ret;
+}
diff --git a/tools/io_uring/liburing.h b/tools/io_uring/liburing.h
new file mode 100644 (file)
index 0000000..cab0f50
--- /dev/null
@@ -0,0 +1,143 @@
+#ifndef LIB_URING_H
+#define LIB_URING_H
+
+#include <sys/uio.h>
+#include <signal.h>
+#include <string.h>
+#include "../../include/uapi/linux/io_uring.h"
+
+/*
+ * Library interface to io_uring
+ */
+struct io_uring_sq {
+       unsigned *khead;
+       unsigned *ktail;
+       unsigned *kring_mask;
+       unsigned *kring_entries;
+       unsigned *kflags;
+       unsigned *kdropped;
+       unsigned *array;
+       struct io_uring_sqe *sqes;
+
+       unsigned sqe_head;
+       unsigned sqe_tail;
+
+       size_t ring_sz;
+};
+
+struct io_uring_cq {
+       unsigned *khead;
+       unsigned *ktail;
+       unsigned *kring_mask;
+       unsigned *kring_entries;
+       unsigned *koverflow;
+       struct io_uring_cqe *cqes;
+
+       size_t ring_sz;
+};
+
+struct io_uring {
+       struct io_uring_sq sq;
+       struct io_uring_cq cq;
+       int ring_fd;
+};
+
+/*
+ * System calls
+ */
+extern int io_uring_setup(unsigned entries, struct io_uring_params *p);
+extern int io_uring_enter(unsigned fd, unsigned to_submit,
+       unsigned min_complete, unsigned flags, sigset_t *sig);
+extern int io_uring_register(int fd, unsigned int opcode, void *arg,
+       unsigned int nr_args);
+
+/*
+ * Library interface
+ */
+extern int io_uring_queue_init(unsigned entries, struct io_uring *ring,
+       unsigned flags);
+extern int io_uring_queue_mmap(int fd, struct io_uring_params *p,
+       struct io_uring *ring);
+extern void io_uring_queue_exit(struct io_uring *ring);
+extern int io_uring_get_completion(struct io_uring *ring,
+       struct io_uring_cqe **cqe_ptr);
+extern int io_uring_wait_completion(struct io_uring *ring,
+       struct io_uring_cqe **cqe_ptr);
+extern int io_uring_submit(struct io_uring *ring);
+extern struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring);
+
+/*
+ * Command prep helpers
+ */
+static inline void io_uring_sqe_set_data(struct io_uring_sqe *sqe, void *data)
+{
+       sqe->user_data = (unsigned long) data;
+}
+
+static inline void io_uring_prep_rw(int op, struct io_uring_sqe *sqe, int fd,
+                                   void *addr, unsigned len, off_t offset)
+{
+       memset(sqe, 0, sizeof(*sqe));
+       sqe->opcode = op;
+       sqe->fd = fd;
+       sqe->off = offset;
+       sqe->addr = (unsigned long) addr;
+       sqe->len = len;
+}
+
+static inline void io_uring_prep_readv(struct io_uring_sqe *sqe, int fd,
+                                      struct iovec *iovecs, unsigned nr_vecs,
+                                      off_t offset)
+{
+       io_uring_prep_rw(IORING_OP_READV, sqe, fd, iovecs, nr_vecs, offset);
+}
+
+static inline void io_uring_prep_read_fixed(struct io_uring_sqe *sqe, int fd,
+                                           void *buf, unsigned nbytes,
+                                           off_t offset)
+{
+       io_uring_prep_rw(IORING_OP_READ_FIXED, sqe, fd, buf, nbytes, offset);
+}
+
+static inline void io_uring_prep_writev(struct io_uring_sqe *sqe, int fd,
+                                       struct iovec *iovecs, unsigned nr_vecs,
+                                       off_t offset)
+{
+       io_uring_prep_rw(IORING_OP_WRITEV, sqe, fd, iovecs, nr_vecs, offset);
+}
+
+static inline void io_uring_prep_write_fixed(struct io_uring_sqe *sqe, int fd,
+                                            void *buf, unsigned nbytes,
+                                            off_t offset)
+{
+       io_uring_prep_rw(IORING_OP_WRITE_FIXED, sqe, fd, buf, nbytes, offset);
+}
+
+static inline void io_uring_prep_poll_add(struct io_uring_sqe *sqe, int fd,
+                                         short poll_mask)
+{
+       memset(sqe, 0, sizeof(*sqe));
+       sqe->opcode = IORING_OP_POLL_ADD;
+       sqe->fd = fd;
+       sqe->poll_events = poll_mask;
+}
+
+static inline void io_uring_prep_poll_remove(struct io_uring_sqe *sqe,
+                                            void *user_data)
+{
+       memset(sqe, 0, sizeof(*sqe));
+       sqe->opcode = IORING_OP_POLL_REMOVE;
+       sqe->addr = (unsigned long) user_data;
+}
+
+static inline void io_uring_prep_fsync(struct io_uring_sqe *sqe, int fd,
+                                      int datasync)
+{
+       memset(sqe, 0, sizeof(*sqe));
+       sqe->opcode = IORING_OP_FSYNC;
+       sqe->fd = fd;
+       if (datasync)
+               sqe->fsync_flags = IORING_FSYNC_DATASYNC;
+}
+
+#endif
diff --git a/tools/io_uring/queue.c b/tools/io_uring/queue.c
new file mode 100644 (file)
index 0000000..88505e8
--- /dev/null
@@ -0,0 +1,164 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include "liburing.h"
+#include "barrier.h"
+
+static int __io_uring_get_completion(struct io_uring *ring,
+                                    struct io_uring_cqe **cqe_ptr, int wait)
+{
+       struct io_uring_cq *cq = &ring->cq;
+       const unsigned mask = *cq->kring_mask;
+       unsigned head;
+       int ret;
+
+       *cqe_ptr = NULL;
+       head = *cq->khead;
+       do {
+               /*
+                * It's necessary to use a read_barrier() before reading
+                * the CQ tail, since the kernel updates it locklessly. The
+                * kernel has the matching store barrier for the update. The
+                * kernel also ensures that previous stores to CQEs are ordered
+                * with the tail update.
+                */
+               read_barrier();
+               if (head != *cq->ktail) {
+                       *cqe_ptr = &cq->cqes[head & mask];
+                       break;
+               }
+               if (!wait)
+                       break;
+               ret = io_uring_enter(ring->ring_fd, 0, 1,
+                                       IORING_ENTER_GETEVENTS, NULL);
+               if (ret < 0)
+                       return -errno;
+       } while (1);
+
+       if (*cqe_ptr) {
+               *cq->khead = head + 1;
+               /*
+                * Ensure that the kernel sees our new head, the kernel has
+                * the matching read barrier.
+                */
+               write_barrier();
+       }
+
+       return 0;
+}
+
+/*
+ * Return an IO completion, if one is readily available
+ */
+int io_uring_get_completion(struct io_uring *ring,
+                           struct io_uring_cqe **cqe_ptr)
+{
+       return __io_uring_get_completion(ring, cqe_ptr, 0);
+}
+
+/*
+ * Return an IO completion, waiting for it if necessary
+ */
+int io_uring_wait_completion(struct io_uring *ring,
+                            struct io_uring_cqe **cqe_ptr)
+{
+       return __io_uring_get_completion(ring, cqe_ptr, 1);
+}
+
+/*
+ * Submit sqes acquired from io_uring_get_sqe() to the kernel.
+ *
+ * Returns number of sqes submitted
+ */
+int io_uring_submit(struct io_uring *ring)
+{
+       struct io_uring_sq *sq = &ring->sq;
+       const unsigned mask = *sq->kring_mask;
+       unsigned ktail, ktail_next, submitted;
+       int ret;
+
+       /*
+        * If we have pending IO in the kring, submit it first. We need a
+        * read barrier here to match the kernels store barrier when updating
+        * the SQ head.
+        */
+       read_barrier();
+       if (*sq->khead != *sq->ktail) {
+               submitted = *sq->kring_entries;
+               goto submit;
+       }
+
+       if (sq->sqe_head == sq->sqe_tail)
+               return 0;
+
+       /*
+        * Fill in sqes that we have queued up, adding them to the kernel ring
+        */
+       submitted = 0;
+       ktail = ktail_next = *sq->ktail;
+       while (sq->sqe_head < sq->sqe_tail) {
+               ktail_next++;
+               read_barrier();
+
+               sq->array[ktail & mask] = sq->sqe_head & mask;
+               ktail = ktail_next;
+
+               sq->sqe_head++;
+               submitted++;
+       }
+
+       if (!submitted)
+               return 0;
+
+       if (*sq->ktail != ktail) {
+               /*
+                * First write barrier ensures that the SQE stores are updated
+                * with the tail update. This is needed so that the kernel
+                * will never see a tail update without the preceeding sQE
+                * stores being done.
+                */
+               write_barrier();
+               *sq->ktail = ktail;
+               /*
+                * The kernel has the matching read barrier for reading the
+                * SQ tail.
+                */
+               write_barrier();
+       }
+
+submit:
+       ret = io_uring_enter(ring->ring_fd, submitted, 0,
+                               IORING_ENTER_GETEVENTS, NULL);
+       if (ret < 0)
+               return -errno;
+
+       return 0;
+}
+
+/*
+ * Return an sqe to fill. Application must later call io_uring_submit()
+ * when it's ready to tell the kernel about it. The caller may call this
+ * function multiple times before calling io_uring_submit().
+ *
+ * Returns a vacant sqe, or NULL if we're full.
+ */
+struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring)
+{
+       struct io_uring_sq *sq = &ring->sq;
+       unsigned next = sq->sqe_tail + 1;
+       struct io_uring_sqe *sqe;
+
+       /*
+        * All sqes are used
+        */
+       if (next - sq->sqe_head > *sq->kring_entries)
+               return NULL;
+
+       sqe = &sq->sqes[sq->sqe_tail & *sq->kring_mask];
+       sq->sqe_tail = next;
+       return sqe;
+}
diff --git a/tools/io_uring/setup.c b/tools/io_uring/setup.c
new file mode 100644 (file)
index 0000000..4da19a7
--- /dev/null
@@ -0,0 +1,103 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+#include "liburing.h"
+
+static int io_uring_mmap(int fd, struct io_uring_params *p,
+                        struct io_uring_sq *sq, struct io_uring_cq *cq)
+{
+       size_t size;
+       void *ptr;
+       int ret;
+
+       sq->ring_sz = p->sq_off.array + p->sq_entries * sizeof(unsigned);
+       ptr = mmap(0, sq->ring_sz, PROT_READ | PROT_WRITE,
+                       MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_SQ_RING);
+       if (ptr == MAP_FAILED)
+               return -errno;
+       sq->khead = ptr + p->sq_off.head;
+       sq->ktail = ptr + p->sq_off.tail;
+       sq->kring_mask = ptr + p->sq_off.ring_mask;
+       sq->kring_entries = ptr + p->sq_off.ring_entries;
+       sq->kflags = ptr + p->sq_off.flags;
+       sq->kdropped = ptr + p->sq_off.dropped;
+       sq->array = ptr + p->sq_off.array;
+
+       size = p->sq_entries * sizeof(struct io_uring_sqe),
+       sq->sqes = mmap(0, size, PROT_READ | PROT_WRITE,
+                               MAP_SHARED | MAP_POPULATE, fd,
+                               IORING_OFF_SQES);
+       if (sq->sqes == MAP_FAILED) {
+               ret = -errno;
+err:
+               munmap(sq->khead, sq->ring_sz);
+               return ret;
+       }
+
+       cq->ring_sz = p->cq_off.cqes + p->cq_entries * sizeof(struct io_uring_cqe);
+       ptr = mmap(0, cq->ring_sz, PROT_READ | PROT_WRITE,
+                       MAP_SHARED | MAP_POPULATE, fd, IORING_OFF_CQ_RING);
+       if (ptr == MAP_FAILED) {
+               ret = -errno;
+               munmap(sq->sqes, p->sq_entries * sizeof(struct io_uring_sqe));
+               goto err;
+       }
+       cq->khead = ptr + p->cq_off.head;
+       cq->ktail = ptr + p->cq_off.tail;
+       cq->kring_mask = ptr + p->cq_off.ring_mask;
+       cq->kring_entries = ptr + p->cq_off.ring_entries;
+       cq->koverflow = ptr + p->cq_off.overflow;
+       cq->cqes = ptr + p->cq_off.cqes;
+       return 0;
+}
+
+/*
+ * For users that want to specify sq_thread_cpu or sq_thread_idle, this
+ * interface is a convenient helper for mmap()ing the rings.
+ * Returns -1 on error, or zero on success.  On success, 'ring'
+ * contains the necessary information to read/write to the rings.
+ */
+int io_uring_queue_mmap(int fd, struct io_uring_params *p, struct io_uring *ring)
+{
+       int ret;
+
+       memset(ring, 0, sizeof(*ring));
+       ret = io_uring_mmap(fd, p, &ring->sq, &ring->cq);
+       if (!ret)
+               ring->ring_fd = fd;
+       return ret;
+}
+
+/*
+ * Returns -1 on error, or zero on success. On success, 'ring'
+ * contains the necessary information to read/write to the rings.
+ */
+int io_uring_queue_init(unsigned entries, struct io_uring *ring, unsigned flags)
+{
+       struct io_uring_params p;
+       int fd;
+
+       memset(&p, 0, sizeof(p));
+       p.flags = flags;
+
+       fd = io_uring_setup(entries, &p);
+       if (fd < 0)
+               return fd;
+
+       return io_uring_queue_mmap(fd, &p, ring);
+}
+
+void io_uring_queue_exit(struct io_uring *ring)
+{
+       struct io_uring_sq *sq = &ring->sq;
+       struct io_uring_cq *cq = &ring->cq;
+
+       munmap(sq->sqes, *sq->kring_entries * sizeof(struct io_uring_sqe));
+       munmap(sq->khead, sq->ring_sz);
+       munmap(cq->khead, cq->ring_sz);
+       close(ring->ring_fd);
+}
diff --git a/tools/io_uring/syscall.c b/tools/io_uring/syscall.c
new file mode 100644 (file)
index 0000000..6b835e5
--- /dev/null
@@ -0,0 +1,40 @@
+/*
+ * Will go away once libc support is there
+ */
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/uio.h>
+#include <signal.h>
+#include "liburing.h"
+
+#if defined(__x86_64) || defined(__i386__)
+#ifndef __NR_sys_io_uring_setup
+#define __NR_sys_io_uring_setup                425
+#endif
+#ifndef __NR_sys_io_uring_enter
+#define __NR_sys_io_uring_enter                426
+#endif
+#ifndef __NR_sys_io_uring_register
+#define __NR_sys_io_uring_register     427
+#endif
+#else
+#error "Arch not supported yet"
+#endif
+
+int io_uring_register(int fd, unsigned int opcode, void *arg,
+                     unsigned int nr_args)
+{
+       return syscall(__NR_sys_io_uring_register, fd, opcode, arg, nr_args);
+}
+
+int io_uring_setup(unsigned entries, struct io_uring_params *p)
+{
+       return syscall(__NR_sys_io_uring_setup, entries, p);
+}
+
+int io_uring_enter(unsigned fd, unsigned to_submit, unsigned min_complete,
+                  unsigned flags, sigset_t *sig)
+{
+       return syscall(__NR_sys_io_uring_enter, fd, to_submit, min_complete,
+                       flags, sig, _NSIG / 8);
+}