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Sourcecode: fio version File versions

mmap.c

/*
 * mmap engine
 *
 * IO engine that reads/writes from files by doing memcpy to/from
 * a memory mapped region of the file.
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>

#include "../fio.h"
#include "../verify.h"

/*
 * Limits us to 1GB of mapped files in total
 */
#define MMAP_TOTAL_SZ   (1 * 1024 * 1024 * 1024UL)

static unsigned long mmap_map_size;
static unsigned long mmap_map_mask;

static int fio_mmap_file(struct thread_data *td, struct fio_file *f,
                   size_t length, off_t off)
{
      int flags = 0;

      if (td_rw(td))
            flags = PROT_READ | PROT_WRITE;
      else if (td_write(td)) {
            flags = PROT_WRITE;

            if (td->o.verify != VERIFY_NONE)
                  flags |= PROT_READ;
      } else
            flags = PROT_READ;

      f->mmap_ptr = mmap(NULL, length, flags, MAP_SHARED, f->fd, off);
      if (f->mmap_ptr == MAP_FAILED) {
            f->mmap_ptr = NULL;
            td_verror(td, errno, "mmap");
            goto err;
      }

      if (!td_random(td)) {
            if (madvise(f->mmap_ptr, length, MADV_SEQUENTIAL) < 0) {
                  td_verror(td, errno, "madvise");
                  goto err;
            }
      } else {
            if (madvise(f->mmap_ptr, length, MADV_RANDOM) < 0) {
                  td_verror(td, errno, "madvise");
                  goto err;
            }
      }

err:
      if (td->error && f->mmap_ptr)
            munmap(f->mmap_ptr, length);
            
      return td->error;
}

/*
 * Just mmap an appropriate portion, we cannot mmap the full extent
 */
static int fio_mmapio_prep_limited(struct thread_data *td, struct io_u *io_u)
{
      struct fio_file *f = io_u->file;

      if (io_u->buflen > mmap_map_size) {
            log_err("fio: bs too big for mmap engine\n");
            return EIO;
      }

      f->mmap_sz = mmap_map_size;
      if (f->mmap_sz  > f->io_size)
            f->mmap_sz = f->io_size;

      f->mmap_off = io_u->offset;

      return fio_mmap_file(td, f, f->mmap_sz, f->mmap_off);
}

/*
 * Attempt to mmap the entire file
 */
static int fio_mmapio_prep_full(struct thread_data *td, struct io_u *io_u)
{
      struct fio_file *f = io_u->file;
      int ret;

      if (fio_file_partial_mmap(f))
            return EINVAL;

      f->mmap_sz = f->io_size;
      f->mmap_off = 0;

      ret = fio_mmap_file(td, f, f->mmap_sz, f->mmap_off);
      if (ret)
            fio_file_set_partial_mmap(f);

      return ret;
}

static int fio_mmapio_prep(struct thread_data *td, struct io_u *io_u)
{
      struct fio_file *f = io_u->file;
      int ret;

      /*
       * It fits within existing mapping, use it
       */
      if (io_u->offset >= f->mmap_off &&
          io_u->offset + io_u->buflen < f->mmap_off + f->mmap_sz)
            goto done;

      /*
       * unmap any existing mapping
       */
      if (f->mmap_ptr) {
            if (munmap(f->mmap_ptr, f->mmap_sz) < 0)
                  return errno;
            f->mmap_ptr = NULL;
      }

      if (fio_mmapio_prep_full(td, io_u)) {
            td_clear_error(td);
            ret = fio_mmapio_prep_limited(td, io_u);
            if (ret)
                  return ret;
      }

done:
      io_u->mmap_data = f->mmap_ptr + io_u->offset - f->mmap_off -
                        f->file_offset;
      return 0;
}

static int fio_mmapio_queue(struct thread_data *td, struct io_u *io_u)
{
      struct fio_file *f = io_u->file;

      fio_ro_check(td, io_u);

      if (io_u->ddir == DDIR_READ)
            memcpy(io_u->xfer_buf, io_u->mmap_data, io_u->xfer_buflen);
      else if (io_u->ddir == DDIR_WRITE)
            memcpy(io_u->mmap_data, io_u->xfer_buf, io_u->xfer_buflen);
      else if (ddir_sync(io_u->ddir)) {
            if (msync(f->mmap_ptr, f->mmap_sz, MS_SYNC)) {
                  io_u->error = errno;
                  td_verror(td, io_u->error, "msync");
            }
      }

      /*
       * not really direct, but should drop the pages from the cache
       */
      if (td->o.odirect && !ddir_sync(io_u->ddir)) {
            if (msync(io_u->mmap_data, io_u->xfer_buflen, MS_SYNC) < 0) {
                  io_u->error = errno;
                  td_verror(td, io_u->error, "msync");
            }
            if (madvise(io_u->mmap_data, io_u->xfer_buflen,  MADV_DONTNEED) < 0) {
                  io_u->error = errno;
                  td_verror(td, io_u->error, "madvise");
            }
      }

      return FIO_Q_COMPLETED;
}

static int fio_mmapio_init(struct thread_data *td)
{
      unsigned long shift, mask;

      mmap_map_size = MMAP_TOTAL_SZ / td->o.nr_files;
      mask = mmap_map_size;
      shift = 0;
      do {
            mask >>= 1;
            if (!mask)
                  break;
            shift++;
      } while (1);
            
      mmap_map_mask = 1UL << shift;
      return 0;
}

static struct ioengine_ops ioengine = {
      .name       = "mmap",
      .version    = FIO_IOOPS_VERSION,
      .init       = fio_mmapio_init,
      .prep       = fio_mmapio_prep,
      .queue            = fio_mmapio_queue,
      .open_file  = generic_open_file,
      .close_file = generic_close_file,
      .get_file_size    = generic_get_file_size,
      .flags            = FIO_SYNCIO | FIO_NOEXTEND,
};

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

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

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