// 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;
}