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Sourcecode: fio version File versions

syslet-rw.c

/*
 * syslet engine
 *
 * IO engine that does regular pread(2)/pwrite(2) to transfer data, but
 * with syslets to make the execution async.
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <malloc.h>
#include <asm/unistd.h>

#include "../fio.h"
#include "../lib/fls.h"

#ifdef FIO_HAVE_SYSLET

#ifdef __NR_pread64
#define __NR_fio_pread  __NR_pread64
#define __NR_fio_pwrite __NR_pwrite64
#else
#define __NR_fio_pread  __NR_pread
#define __NR_fio_pwrite __NR_pwrite
#endif

struct syslet_data {
      struct io_u **events;
      unsigned int nr_events;
      
      struct syslet_ring *ring;
      unsigned int ring_mask;
      void *stack;
};

static void fio_syslet_add_event(struct thread_data *td, struct io_u *io_u)
{
      struct syslet_data *sd = td->io_ops->data;

      assert(sd->nr_events < td->o.iodepth);
      sd->events[sd->nr_events++] = io_u;
}

static void fio_syslet_add_events(struct thread_data *td, unsigned int nr)
{
      struct syslet_data *sd = td->io_ops->data;
      unsigned int i, uidx;

      uidx = sd->ring->user_tail;
      read_barrier();

      for (i = 0; i < nr; i++) {
            unsigned int idx = (i + uidx) & sd->ring_mask;
            struct syslet_completion *comp = &sd->ring->comp[idx];
            struct io_u *io_u = (struct io_u *) (long) comp->caller_data;
            long ret;

            ret = comp->status;
            if (ret <= 0) {
                  io_u->resid = io_u->xfer_buflen;
                  io_u->error = -ret;
            } else {
                  io_u->resid = io_u->xfer_buflen - ret;
                  io_u->error = 0;
            }

            fio_syslet_add_event(td, io_u);
      }
}

static void fio_syslet_wait_for_events(struct thread_data *td)
{
      struct syslet_data *sd = td->io_ops->data;
      struct syslet_ring *ring = sd->ring;

      do {
            unsigned int kh = ring->kernel_head;
            int ret;

            /*
             * first reap events that are already completed
             */
            if (ring->user_tail != kh) {
                  unsigned int nr = kh - ring->user_tail;

                  fio_syslet_add_events(td, nr);
                  ring->user_tail = kh;
                  break;
            }

            /*
             * block waiting for at least one event
             */
            ret = syscall(__NR_syslet_ring_wait, ring, ring->user_tail);
            assert(!ret);
      } while (1);
}

static int fio_syslet_getevents(struct thread_data *td, unsigned int min,
                        unsigned int fio_unused max,
                        struct timespec fio_unused *t)
{
      struct syslet_data *sd = td->io_ops->data;
      long ret;

      /*
       * While we have less events than requested, block waiting for them
       * (if we have to, there may already be more completed events ready
       * for us - see fio_syslet_wait_for_events()
       */
      while (sd->nr_events < min)
            fio_syslet_wait_for_events(td);

      ret = sd->nr_events;
      sd->nr_events = 0;
      return ret;
}

static struct io_u *fio_syslet_event(struct thread_data *td, int event)
{
      struct syslet_data *sd = td->io_ops->data;

      return sd->events[event];
}

static void fio_syslet_prep_sync(struct fio_file *f,
                         struct indirect_registers *regs)
{
      FILL_IN(*regs, __NR_fsync, (long) f->fd);
}

static void fio_syslet_prep_datasync(struct fio_file *f,
                             struct indirect_registers *regs)
{
      FILL_IN(*regs, __NR_fdatasync, (long) f->fd);
}

static void fio_syslet_prep_rw(struct io_u *io_u, struct fio_file *f,
                         struct indirect_registers *regs)
{
      long nr;

      /*
       * prepare rw
       */
      if (io_u->ddir == DDIR_READ)
            nr = __NR_fio_pread;
      else
            nr = __NR_fio_pwrite;

      FILL_IN(*regs, nr, (long) f->fd, (long) io_u->xfer_buf,
            (long) io_u->xfer_buflen, (long) io_u->offset);
}

static void fio_syslet_prep(struct io_u *io_u, struct indirect_registers *regs)
{
      struct fio_file *f = io_u->file;

      if (io_u->ddir == DDIR_SYNC)
            fio_syslet_prep_sync(f, regs);
      else if (io_u->ddir == DDIR_DATASYNC)
            fio_syslet_prep_datasync(f, regs);
      else
            fio_syslet_prep_rw(io_u, f, regs);
}

static void ret_func(void)
{
      syscall(__NR_exit);
}

static int fio_syslet_queue(struct thread_data *td, struct io_u *io_u)
{
      struct syslet_data *sd = td->io_ops->data;
      union indirect_params params;
      struct indirect_registers regs;
      int ret;

      fio_ro_check(td, io_u);

      memset(&params, 0, sizeof(params));
      fill_syslet_args(&params.syslet, sd->ring, (long)io_u, ret_func, sd->stack);

      fio_syslet_prep(io_u, &regs);

      ret = syscall(__NR_indirect, &regs, &params, sizeof(params), 0);
      if (ret == (int) io_u->xfer_buflen) {
            /*
             * completed sync, account. this also catches fsync().
             */
            return FIO_Q_COMPLETED;
      } else if (ret < 0) {
            /*
             * queued for async execution
             */
            if (errno == ESYSLETPENDING)
                  return FIO_Q_QUEUED;
      }

      io_u->error = errno;
      td_verror(td, io_u->error, "xfer");
      return FIO_Q_COMPLETED;
}

static int check_syslet_support(struct syslet_data *sd)
{
      union indirect_params params;
      struct indirect_registers regs;
      pid_t pid, my_pid = getpid();

      memset(&params, 0, sizeof(params));
      fill_syslet_args(&params.syslet, sd->ring, 0, ret_func, sd->stack);

      FILL_IN(regs, __NR_getpid);

      pid = syscall(__NR_indirect, &regs, &params, sizeof(params), 0);
      if (pid == my_pid)
            return 0;

      return 1;
}

static void fio_syslet_cleanup(struct thread_data *td)
{
      struct syslet_data *sd = td->io_ops->data;

      if (sd) {
            free(sd->events);
            free(sd->ring);
            free(sd);
      }
}

static int fio_syslet_init(struct thread_data *td)
{
      struct syslet_data *sd;
      void *ring = NULL, *stack = NULL;
      unsigned int ring_size, ring_nr;

      sd = malloc(sizeof(*sd));
      memset(sd, 0, sizeof(*sd));

      sd->events = malloc(sizeof(struct io_u *) * td->o.iodepth);
      memset(sd->events, 0, sizeof(struct io_u *) * td->o.iodepth);

      /*
       * The ring needs to be a power-of-2, so round it up if we have to
       */
      ring_nr = td->o.iodepth;
      if (ring_nr & (ring_nr - 1))
            ring_nr = 1 << __fls(ring_nr);

      ring_size = sizeof(struct syslet_ring) +
                  ring_nr * sizeof(struct syslet_completion);
      if (posix_memalign(&ring, sizeof(uint64_t), ring_size))
            goto err_mem;
      if (posix_memalign(&stack, page_size, page_size))
            goto err_mem;

      sd->ring = ring;
      sd->ring_mask = ring_nr - 1;
      sd->stack = stack;

      memset(sd->ring, 0, ring_size);
      sd->ring->elements = ring_nr;

      if (!check_syslet_support(sd)) {
            td->io_ops->data = sd;
            return 0;
      }

      log_err("fio: syslets do not appear to work\n");
err_mem:
      free(sd->events);
      if (ring)
            free(ring);
      if (stack)
            free(stack);
      free(sd);
      return 1;
}

static struct ioengine_ops ioengine = {
      .name       = "syslet-rw",
      .version    = FIO_IOOPS_VERSION,
      .init       = fio_syslet_init,
      .queue            = fio_syslet_queue,
      .getevents  = fio_syslet_getevents,
      .event            = fio_syslet_event,
      .cleanup    = fio_syslet_cleanup,
      .open_file  = generic_open_file,
      .close_file = generic_close_file,
      .get_file_size    = generic_get_file_size,
};

#else /* FIO_HAVE_SYSLET */

/*
 * When we have a proper configure system in place, we simply wont build
 * and install this io engine. For now install a crippled version that
 * just complains and fails to load.
 */
static int fio_syslet_init(struct thread_data fio_unused *td)
{
      fprintf(stderr, "fio: syslet not available\n");
      return 1;
}

static struct ioengine_ops ioengine = {
      .name       = "syslet-rw",
      .version    = FIO_IOOPS_VERSION,
      .init       = fio_syslet_init,
};

#endif /* FIO_HAVE_SYSLET */

static void fio_init fio_syslet_register(void)
{
      register_ioengine(&ioengine);
}

static void fio_exit fio_syslet_unregister(void)
{
      unregister_ioengine(&ioengine);
}

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