wip: cp c io_uring
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669781b86f
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c88fabdf2f
@ -1,3 +0,0 @@
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CC=clang
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all: cp
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201
examples/cp.c
201
examples/cp.c
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#include <fcntl.h>
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#include <linux/fs.h>
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#include <linux/io_uring.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <sys/uio.h>
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#include <unistd.h>
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#define QUEUE_DEPTH 16
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#define IO_BLOCK_SIZE 4096
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/*
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* io_uring structures
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*/
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struct submission_ring {
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unsigned *head;
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unsigned *tail;
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unsigned *ring_mask;
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unsigned *ring_entries;
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unsigned *flags;
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unsigned *array;
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};
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struct completion_ring {
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unsigned *head;
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unsigned *tail;
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unsigned *ring_mask;
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unsigned *ring_entries;
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struct io_uring_cqe *cqes;
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};
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struct ring {
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int fd;
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struct submission_ring sq_ring;
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struct io_uring_sqe *sqes;
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struct completion_ring cq_ring;
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};
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/*
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* File info struct
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*/
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struct file {
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int fd;
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off_t size;
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struct iovec iovecs[];
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};
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/*
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* Generate syscall wrappers that are still not in stdlib
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*/
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int io_uring_setup(unsigned entries, struct io_uring_params *p) {
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return (int)syscall(__NR_io_uring_setup, entries, p);
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}
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int io_uring_enter(int ring_fd, unsigned int to_submit,
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unsigned int min_complete, unsigned int flags) {
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return (int)syscall(__NR_io_uring_enter, ring_fd, to_submit, min_complete,
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flags, NULL, 0);
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}
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/*
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* Setup a ring.
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*/
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int init_uring(struct ring *r) {
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struct submission_ring *sring = &r->sq_ring;
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struct completion_ring *cring = &r->cq_ring;
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struct io_uring_params p;
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void *sq_ptr, *cq_ptr;
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memset(&p, 0, sizeof(p));
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r->fd = io_uring_setup(QUEUE_DEPTH, &p);
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if (r->fd < 0) {
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perror("io_uring_setup");
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return 1;
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}
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int submission_ring_size = p.sq_off.array + p.sq_entries * sizeof(void *);
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int completion_ring_size =
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p.cq_off.cqes + p.cq_entries * sizeof(struct io_uring_cqe);
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if (p.features & IORING_FEAT_SINGLE_MMAP) {
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if (completion_ring_size > submission_ring_size) {
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submission_ring_size = completion_ring_size;
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}
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completion_ring_size = submission_ring_size;
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} else {
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fprintf(
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stderr,
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"requires unified queue mapping, needs kernel version 5.4 or above\n");
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return 1;
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}
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sq_ptr = mmap(0, submission_ring_size, PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_POPULATE, r->fd, IORING_OFF_SQ_RING);
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if (sq_ptr == MAP_FAILED) {
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perror("mmap");
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return 1;
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}
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cq_ptr = sq_ptr;
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sring->head = sq_ptr + p.sq_off.head;
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sring->tail = sq_ptr + p.sq_off.tail;
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sring->ring_mask = sq_ptr + p.sq_off.ring_mask;
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sring->ring_entries = sq_ptr + p.sq_off.ring_entries;
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sring->flags = sq_ptr + p.sq_off.flags;
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sring->array = sq_ptr + p.sq_off.array;
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cring->head = cq_ptr + p.cq_off.head;
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cring->tail = cq_ptr + p.cq_off.tail;
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cring->ring_mask = cq_ptr + p.cq_off.ring_mask;
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cring->ring_entries = cq_ptr + p.cq_off.ring_entries;
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cring->cqes = cq_ptr + p.cq_off.cqes;
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r->sqes = mmap(0, p.sq_entries * sizeof(struct io_uring_sqe),
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PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, r->fd,
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IORING_OFF_SQES);
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if (r->sqes == MAP_FAILED) {
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perror("mmap");
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return 1;
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}
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return 0;
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}
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/*
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* Get size of regular file or error otherwise.
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*/
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off_t get_file_size(int fd) {
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struct stat st;
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if (fstat(fd, &st) < 0) {
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perror("fstat");
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return -1;
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}
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if (S_ISREG(st.st_mode)) {
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return st.st_size;
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} else {
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return -1;
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}
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}
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/*
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* Open file and prepare a file struct.
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*/
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int prep_file(struct file **f, char *path, int flags) {
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int fd = open(path, flags);
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if (fd == -1) {
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perror("open");
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return -1;
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}
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off_t size = get_file_size(fd);
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if (size == -1) {
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return -1;
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}
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off_t blocks = size / IO_BLOCK_SIZE;
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if (size % IO_BLOCK_SIZE)
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blocks++;
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*f = malloc(sizeof(struct file) + sizeof(struct iovec) * blocks);
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if (!*f) {
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fprintf(stderr, "malloc failed\n");
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return -1;
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}
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return 0;
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}
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int main(int argc, char **argv) {
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if (argc < 3) {
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fprintf(stderr, "usage: %s <src> <dst>\n", argv[0]);
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return 1;
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}
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struct ring r;
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memset(&r, 0, sizeof(r));
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if (init_uring(&r)) {
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fprintf(stderr, "uring setup failed\n");
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return 1;
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}
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struct file *src, *dst;
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if (prep_file(&src, argv[1], O_RDONLY) == -1) {
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return 1;
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}
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if (prep_file(&dst, argv[2], O_WRONLY | O_CREAT | O_TRUNC) == -1) {
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return 1;
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}
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return 0;
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}
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13
examples/cp/Makefile
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13
examples/cp/Makefile
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C=clang
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all: c ml
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clean:
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rm -f c ml
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c: cp.c
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${C} -o c cp.c
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ml: cp.ml
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opam switch default
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ocamlopt -o ml cp.ml
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162
examples/cp/cp.c
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162
examples/cp/cp.c
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <sys/uio.h>
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#include <unistd.h>
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#include <liburing.h>
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#include <linux/fs.h>
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#define QUEUE_DEPTH 16
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#define IO_BLOCK_SIZE 4096
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#define BUFFER_NUM_BLOCKS 8
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/*
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* Data struct for SQEs and CQEs.
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*/
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struct io_data {
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bool read;
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off_t offset;
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int len;
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};
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/*
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* Get size of regular file or error otherwise.
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*/
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off_t get_file_size(int fd) {
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struct stat st;
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if (fstat(fd, &st) < 0) {
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perror("fstat");
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return -1;
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}
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if (S_ISREG(st.st_mode)) {
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return st.st_size;
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} else {
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return -1;
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}
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}
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/*
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* Submit a linked pair of read/write requests
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*/
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int prep_read_write_pair(struct io_uring *ring, int src_fd, int dst_fd,
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off_t offset, void *buf, int len) {
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struct io_uring_sqe *sqe;
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struct io_data *data;
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sqe = io_uring_get_sqe(ring);
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if (!sqe)
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return 1;
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io_uring_prep_read(sqe, src_fd, buf, len, offset);
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data = malloc(sizeof(*data));
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data->read = 1;
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data->len = len;
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data->offset = offset;
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sqe->flags |= IOSQE_IO_LINK; // add as a dependency of the write
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io_uring_sqe_set_data(sqe, data);
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sqe = io_uring_get_sqe(ring);
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if (!sqe) {
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io_uring_submit_and_wait(ring, 1);
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sqe = io_uring_get_sqe(ring);
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if (!sqe)
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return 2;
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}
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io_uring_prep_write(sqe, dst_fd, buf, len, offset);
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data = malloc(sizeof(*data));
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data->read = 0;
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data->len = len;
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data->offset = offset;
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io_uring_sqe_set_data(sqe, data);
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return 0;
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}
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/*
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* Await and handle completion entries.
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*/
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int await_cqes(struct io_uring *ring, unsigned int wait_nr) {
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struct io_uring_cqe *cqe;
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struct io_data *data;
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io_uring_submit(ring);
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for (int i = 0; i < wait_nr; i++) {
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int ret;
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if ((ret = io_uring_wait_cqe(ring, &cqe))) {
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fprintf(stderr, "io_uring_wait_cqe: %d\n", ret);
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return 1;
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}
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}
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return 0;
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}
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int main(int argc, char **argv) {
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// argument validation
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if (argc < 3) {
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fprintf(stderr, "usage: %s <src> <dst>\n", argv[0]);
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return 1;
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}
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// load files
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int src_fd, dst_fd;
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off_t src_len;
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if ((src_fd = open(argv[1], O_RDONLY)) == -1) {
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perror("open");
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return 1;
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}
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if ((dst_fd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC)) == -1) {
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perror("open");
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return 1;
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}
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if ((src_len = get_file_size(src_fd)) == -1) {
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return 1;
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}
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// prepare uring
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struct io_uring ring;
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io_uring_queue_init(QUEUE_DEPTH, &ring, 0);
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// perform copy
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void *buf;
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if ((buf = mmap(0, IO_BLOCK_SIZE * BUFFER_NUM_BLOCKS, PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_ANONYMOUS, -1, 0)) == MAP_FAILED) {
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perror("mmap");
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return 1;
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}
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off_t blocks =
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(src_len / IO_BLOCK_SIZE) + ((src_len % IO_BLOCK_SIZE) > 0 ? 1 : 0);
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for (off_t i = 0; i < blocks; i++) {
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int section = i % BUFFER_NUM_BLOCKS;
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void *base = buf + (IO_BLOCK_SIZE * section);
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off_t len;
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if (i == blocks - 1) {
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len = src_len % IO_BLOCK_SIZE;
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} else {
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len = IO_BLOCK_SIZE;
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}
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prep_read_write_pair(&ring, src_fd, dst_fd, i * IO_BLOCK_SIZE, base, len);
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if (await_cqes(&ring, 2)) {
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return 1;
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}
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}
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return 0;
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}
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