text: // 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 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", 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;
  }
  