Re: [PATCH 1/1] virtio: add VIRTIO_F_IN_ORDER to header file

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Sep 05, 2021 at 03:09:11PM +0300, Max Gurtovoy wrote:
> For now only add this definition from the spec. In the future, The
> drivers should negotiate this feature to optimize the performance.
> 
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>

So I think IN_ORDER was a mistake since it breaks ability
to do pagefaults efficiently without stopping the ring.
I think that VIRTIO_F_PARTIAL_ORDER is a better option -
am working on finalizing that proposal, will post RSN now.


> ---
>  include/uapi/linux/virtio_config.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> index b5eda06f0d57..3fcdc4ab6f19 100644
> --- a/include/uapi/linux/virtio_config.h
> +++ b/include/uapi/linux/virtio_config.h
> @@ -82,6 +82,12 @@
>  /* This feature indicates support for the packed virtqueue layout. */
>  #define VIRTIO_F_RING_PACKED		34
>  
> +/*
> + * This feature indicates that all buffers are used by the device in the same
> + * order in which they have been made available.
> + */
> +#define VIRTIO_F_IN_ORDER              35
> +
>  /*
>   * This feature indicates that memory accesses by the driver and the
>   * device are ordered in a way described by the platform.
> -- 
> 2.18.1