io_uring: kill io_uring userspace examples

F:	include/trace/events/io_uring.h

F:	include/uapi/linux/io_uring.h

F:	io_uring/

F:	tools/io_uring/

IPMI SUBSYSTEM

M:	Corey Minyard <minyard@acm.org>

# 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) -o $@ $^ $(LDLIBS)

io_uring-cp: setup.o syscall.o queue.o

clean:

	$(RM) io_uring-cp io_uring-bench *.o

.PHONY: all clean

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

#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

// 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"

#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;

	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 lk_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;

			}

		}

		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", lk_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;

	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);

	reap = calls = done = 0;

	do {

		unsigned long this_done = 0;

		unsigned long this_reap = 0;

		unsigned long this_call = 0;

		unsigned long rpc = 0, ipc = 0;

		sleep(1);

		this_done += s->done;

		this_call += s->calls;

		this_reap += s->reaps;

		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)\n",

				this_done - done, rpc, ipc, s->inflight,

				fdepths);

		done = this_done;

		calls = this_call;

		reap = this_reap;

	} while (!finish);

	pthread_join(s->thread, &ret);

	close(s->ring_fd);

	free(fdepths);

	return 0;

}