[dpdk-dev] [PATCH] net/virtio-user: send kick to tx queue to notify backend on initialization

Steven Luong (sluong) sluong at cisco.com
Thu Aug 3 16:12:34 CEST 2017


Maxime,

Thank you so much for the reply.

1. It’s about conforming to the spec. Please read the text as I quoted in the email. A non-conforming implementation does not communicate with a conforming implementation such as VPP.
2. QEMU’s implementation is conforming and it is sending kick for both TX and RX queues upon initialization.

Steven

On 8/3/17, 2:37 AM, "dev on behalf of Maxime Coquelin" <dev-bounces at dpdk.org on behalf of maxime.coquelin at redhat.com> wrote:

    Hi Steven,
    
    On 08/01/2017 06:17 PM, Steven wrote:
    > Acccording to the spec, https://fossies.org/linux/qemu/docs/specs/vhost-user.txt
    > 
    > client must start ring upon receiving a kick (that is, detecting that file
    > descriptor is reachable) on the descriptor specified by
    > VHOST_USER_SET_VRING_KICK.
    > 
    > The code sends a kick to the rx queue. It is missing sending a kick for the
    > tx queue. This patch is to add the missing code to comply with the spec.
    > 
    > Signed-off-by: Steven <sluong at cisco.com>
    > ---
    >   drivers/net/virtio/virtio_ethdev.c | 5 +++++
    >   1 file changed, 5 insertions(+)
    > 
    > diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
    > index 00a3122..6362e14 100644
    > --- a/drivers/net/virtio/virtio_ethdev.c
    > +++ b/drivers/net/virtio/virtio_ethdev.c
    > @@ -1747,6 +1747,11 @@ virtio_dev_start(struct rte_eth_dev *dev)
    >   		virtqueue_notify(rxvq->vq);
    >   	}
    >   
    > +	for (i = 0; i < dev->data->nb_tx_queues; i++) {
    > +		txvq = dev->data->tx_queues[i];
    > +		virtqueue_notify(txvq->vq);
    > +	}
    > +
    
    I'm not sure to get why we would need to send Txq notification whereas
    no packet have been enqueued. That said, I don't think it hurts.
    
    Steven, does it solve a real problem you are facing with virtio-user?
    
    Yuanhan, what's your opinion on this?
    
    Cheers,
    Maxime
    



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