Re: [virtio-dev] [PATCH v14] virtio-net: support the virtqueue coalescing moderation

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

On Tue, Apr 04, 2023 at 04:32:07PM +0000, Parav Pandit wrote:
> 
> > From: Halil Pasic <pasic@linux.ibm.com>
> > Sent: Tuesday, April 4, 2023 12:29 PM
> > 
> > On Thu, 23 Mar 2023 23:24:22 +0800
> > Heng Qi <hengqi@linux.alibaba.com> wrote:
> > 
> > > +struct virtio_net_ctrl_coal_vq {
> > > +    le16 vqn;
> > > +    le16 reserved;
> > > +    struct virtio_net_ctrl_coal coal; };
> > > +
> > >  #define VIRTIO_NET_CTRL_NOTF_COAL 6
> > >   #define VIRTIO_NET_CTRL_NOTF_COAL_TX_SET  0
> > >   #define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET 1
> > > + #define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET 2 #define
> > > + VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET 3
> > >  \end{lstlisting}
> > >
> > >  Coalescing parameters:
> > >  \begin{itemize}
> > > +\item \field{vqn}: The virtqueue number of an enabled transmit or receive
> > virtqueue.
> > 
> > Just to be on the safe side: VIRTIO_F_NOTIF_CONFIG_DATA has been
> > negotiated, and queue_select != queue_notify_data, is vqn supposed to contain
> > queue_notify_data or the number/index that is used for queue_select (I'm
> > talking about the PCI transport case)?
> Vqn has zero relation to notification config data feature and featue bit.
> It is the real vqn enabled via queue_select.
> 
> Once the vqn is renamed to vq_notify_id, we won't have this confusion anymore.

vqn here is the index. queue_select is also the index.

Inside notifications-le.c we have:
le32 {
        vqn : 16;
        next_off : 15;
        next_wrap : 1;
};

vqn here is queue_notify_data.


-- 
MST