Re: [Qemu-devel] [RFC 07/12] Store the data to send also in iovec

[Paolo Bonzini <pbonzini@redhat.com>]

Il 21/03/2013 10:09, Orit Wasserman ha scritto:
> All data is still copied into the static buffer.
> 
> Signed-off-by: Orit Wasserman <owasserm@redhat.com>
> ---
>  savevm.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/savevm.c b/savevm.c
> index ec64533..d5834ca 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -114,6 +114,7 @@ void qemu_announce_self(void)
>  /* savevm/loadvm support */
>  
>  #define IO_BUF_SIZE 32768
> +#define MAX_IOV_SIZE 64

You could use IOV_MAX, or min(IOV_MAX, 64).  The 64 should be tuned on a
good 10G network...

Paolo

>  struct QEMUFile {
>      const QEMUFileOps *ops;
> @@ -129,6 +130,9 @@ struct QEMUFile {
>      int buf_size; /* 0 when writing */
>      uint8_t buf[IO_BUF_SIZE];
>  
> +    struct iovec iov[MAX_IOV_SIZE];
> +    unsigned int iovcnt;
> +
>      int last_error;
>  };
>  
> @@ -546,6 +550,7 @@ static void qemu_fflush(QEMUFile *f)
>              f->pos += f->buf_index;
>          }
>          f->buf_index = 0;
> +        f->iovcnt = 0;
>      }
>      if (ret < 0) {
>          qemu_file_set_error(f, ret);
> @@ -638,12 +643,14 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
>          if (l > size)
>              l = size;
>          memcpy(f->buf + f->buf_index, buf, l);
> +        f->iov[f->iovcnt].iov_base = f->buf + f->buf_index;
> +        f->iov[f->iovcnt++].iov_len = l;
>          f->is_write = 1;
>          f->buf_index += l;
>          f->bytes_xfer += l;
>          buf += l;
>          size -= l;
> -        if (f->buf_index >= IO_BUF_SIZE) {
> +        if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
>              qemu_fflush(f);
>              if (qemu_file_get_error(f)) {
>                  break;
> @@ -667,8 +674,10 @@ void qemu_put_byte(QEMUFile *f, int v)
>      f->buf[f->buf_index++] = v;
>      f->is_write = 1;
>      f->bytes_xfer += 1;
> +    f->iov[f->iovcnt].iov_base = f->buf + (f->buf_index - 1);
> +    f->iov[f->iovcnt++].iov_len = 1;
>  
> -    if (f->buf_index >= IO_BUF_SIZE) {
> +    if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) {
>          qemu_fflush(f);
>      }
>  }
>