Re: [Qemu-block] [RFC v6] RBD: Add support readv,writev for rbd

[Jaze Lee]

If I test , which cache mode i should choose ?

writeback? or none? or default?












2017-02-21 14:50 GMT+08:00  <address@hidden>:
> From: tianqing <address@hidden>
>
> Rbd can do readv and writev directly, so wo do not need to transform
> iov to buf or vice versa any more.
>
> Signed-off-by: tianqing <address@hidden>
> ---
>  block/rbd.c | 80 
> ++++++++++++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 56 insertions(+), 24 deletions(-)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index a57b3e3..22e8e69 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -62,6 +62,13 @@
>  #define RBD_MAX_SNAP_NAME_SIZE 128
>  #define RBD_MAX_SNAPS 100
>
> +/* The LIBRBD_SUPPORTS_IOVEC is defined in librbd.h */
> +#ifdef LIBRBD_SUPPORTS_IOVEC
> +#define LIBRBD_USE_IOVEC 1
> +#else
> +#define LIBRBD_USE_IOVEC 0
> +#endif
> +
>  typedef enum {
>      RBD_AIO_READ,
>      RBD_AIO_WRITE,
> @@ -310,6 +317,17 @@ static int qemu_rbd_set_conf(rados_t cluster, const char 
> *conf,
>      return ret;
>  }
>
> +static void qemu_rbd_memset(RADOSCB *rcb, int64_t offs)
> +{
> +    if (LIBRBD_USE_IOVEC) {
> +        RBDAIOCB *acb = rcb->acb;
> +        iov_memset(acb->qiov->iov, acb->qiov->niov, offs, 0,
> +                   acb->qiov->size - offs);
> +    } else {
> +        memset(rcb->buf + offs, 0, rcb->size - offs);
> +    }
> +}
> +
>  static int qemu_rbd_create(const char *filename, QemuOpts *opts, Error 
> **errp)
>  {
>      Error *local_err = NULL;
> @@ -426,11 +444,11 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
>          }
>      } else {
>          if (r < 0) {
> -            memset(rcb->buf, 0, rcb->size);
> +            qemu_rbd_memset(rcb, 0);
>              acb->ret = r;
>              acb->error = 1;
>          } else if (r < rcb->size) {
> -            memset(rcb->buf + r, 0, rcb->size - r);
> +            qemu_rbd_memset(rcb, r);
>              if (!acb->error) {
>                  acb->ret = rcb->size;
>              }
> @@ -441,10 +459,13 @@ static void qemu_rbd_complete_aio(RADOSCB *rcb)
>
>      g_free(rcb);
>
> -    if (acb->cmd == RBD_AIO_READ) {
> -        qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
> +    if (!LIBRBD_USE_IOVEC) {
> +        if (acb->cmd == RBD_AIO_READ) {
> +            qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
> +        }
> +        qemu_vfree(acb->bounce);
>      }
> -    qemu_vfree(acb->bounce);
> +
>      acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
>
>      qemu_aio_unref(acb);
> @@ -655,7 +676,6 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>      RBDAIOCB *acb;
>      RADOSCB *rcb = NULL;
>      rbd_completion_t c;
> -    char *buf;
>      int r;
>
>      BDRVRBDState *s = bs->opaque;
> @@ -664,27 +684,29 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>      acb->cmd = cmd;
>      acb->qiov = qiov;
>      assert(!qiov || qiov->size == size);
> -    if (cmd == RBD_AIO_DISCARD || cmd == RBD_AIO_FLUSH) {
> -        acb->bounce = NULL;
> -    } else {
> -        acb->bounce = qemu_try_blockalign(bs, qiov->size);
> -        if (acb->bounce == NULL) {
> -            goto failed;
> +
> +    rcb = g_new(RADOSCB, 1);
> +
> +    if (!LIBRBD_USE_IOVEC) {
> +        if (cmd == RBD_AIO_DISCARD || cmd == RBD_AIO_FLUSH) {
> +            acb->bounce = NULL;
> +        } else {
> +            acb->bounce = qemu_try_blockalign(bs, qiov->size);
> +            if (acb->bounce == NULL) {
> +                goto failed;
> +            }
>          }
> +        if (cmd == RBD_AIO_WRITE) {
> +            qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
> +        }
> +        rcb->buf = acb->bounce;
>      }
> +
>      acb->ret = 0;
>      acb->error = 0;
>      acb->s = s;
>
> -    if (cmd == RBD_AIO_WRITE) {
> -        qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
> -    }
> -
> -    buf = acb->bounce;
> -
> -    rcb = g_new(RADOSCB, 1);
>      rcb->acb = acb;
> -    rcb->buf = buf;
>      rcb->s = acb->s;
>      rcb->size = size;
>      r = rbd_aio_create_completion(rcb, (rbd_callback_t) rbd_finish_aiocb, 
> &c);
> @@ -694,10 +716,18 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>
>      switch (cmd) {
>      case RBD_AIO_WRITE:
> -        r = rbd_aio_write(s->image, off, size, buf, c);
> +#ifdef LIBRBD_SUPPORTS_IOVEC
> +            r = rbd_aio_writev(s->image, qiov->iov, qiov->niov, off, c);
> +#else
> +            r = rbd_aio_write(s->image, off, size, rcb->buf, c);
> +#endif
>          break;
>      case RBD_AIO_READ:
> -        r = rbd_aio_read(s->image, off, size, buf, c);
> +#ifdef LIBRBD_SUPPORTS_IOVEC
> +            r = rbd_aio_readv(s->image, qiov->iov, qiov->niov, off, c);
> +#else
> +            r = rbd_aio_read(s->image, off, size, rcb->buf, c);
> +#endif
>          break;
>      case RBD_AIO_DISCARD:
>          r = rbd_aio_discard_wrapper(s->image, off, size, c);
> @@ -712,14 +742,16 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs,
>      if (r < 0) {
>          goto failed_completion;
>      }
> -
>      return &acb->common;
>
>  failed_completion:
>      rbd_aio_release(c);
>  failed:
>      g_free(rcb);
> -    qemu_vfree(acb->bounce);
> +    if (!LIBRBD_USE_IOVEC) {
> +        qemu_vfree(acb->bounce);
> +    }
> +
>      qemu_aio_unref(acb);
>      return NULL;
>  }
> --
> 2.10.2
>



-- 
谦谦君子