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From: Tiwei Bie <tiwei.bie@intel.com>
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Subject: Re: [dpdk-dev] net/virtio: fix vector Rx break caused by rxq
flushing
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Hi Zhike,
On Wed, Jan 03, 2018 at 08:21:26AM +0000, 王志克 wrote:
> Hi Tiwei,
>
> Thanks for your help and info.
>
> I have another question about your previous fix below.
> You mentioned that " Otherwise it will lead to incorrect packet collection for port state." Do you mean port statistics? Or such packets may leads to issue, like more TCP restransmission? Thanks.
>
I was just repeating the problem description from another
team who raised the issue. The unexpected behavior caused
some problems when they use virtio PMD. But I don't know
the details of the problems they met. :(
Best regards,
Tiwei Bie
>
> commit d8227497ec5c3de75fe378e09fc9673ae097fa73
> Author: Tiwei Bie <tiwei.bie@intel.com>
> Date: Fri Oct 20 10:09:28 2017 +0800
>
> net/virtio: flush Rx queues on start
>
> After starting a device, the driver shouldn't deliver the
> packets that already existed before the device is started
> to applications. Otherwise it will lead to incorrect packet
> collection for port state. This patch fixes this issue by
> flushing the Rx queues when starting the device.
>
>
> Br,
> Wang Zhike
> -----Original Message-----
> From: Tiwei Bie [mailto:tiwei.bie@intel.com]
> Sent: Saturday, December 30, 2017 12:02 PM
> To: 王志克
> Cc: dev@dpdk.org; bluca@debian.org; yliu@fridaylinux.org
> Subject: Re: net/virtio: fix vector Rx break caused by rxq flushing
>
> Hi Zhike,
>
> On Fri, Dec 29, 2017 at 01:02:04PM +0000, 王志克 wrote:
> > Hi tiwei,
> >
> > Can you please provide a patch for 16.11.4? Thanks.
> >
>
> Normally, most commits in the stable tree are backported
> from the commits in the mainline tree which contains below
> Cc line:
>
> Cc: stable@dpdk.org
>
> This patch also contains such line. So after this patch
> is applied to the mainline tree, it will be backported.
>
> If you need the fix right now, you can download the latest
> patch (which has been applied to dpdk-next-virtio tree)
> from here:
>
> https://dpdk.org/dev/patchwork/patch/32061/
>
> It can be applied to DPDK 16.11.4 with the patch command.
> After the patching, one small change is needed to get it
> work:
>
> diff --git a/drivers/net/virtio/virtqueue.c b/drivers/net/virtio/virtqueue.c
> index 7fd8604..0e24194 100644
> --- a/drivers/net/virtio/virtqueue.c
> +++ b/drivers/net/virtio/virtqueue.c
> @@ -88,7 +88,7 @@ virtqueue_rxvq_flush(struct virtqueue *vq)
> for (i = 0; i < nb_used; i++) {
> used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> uep = &vq->vq_ring.used->ring[used_idx];
> - if (hw->use_simple_rx) {
> + if (hw->use_simple_rxtx) {
> desc_idx = used_idx;
> rte_pktmbuf_free(vq->sw_ring[desc_idx]);
> vq->vq_free_cnt++;
> @@ -104,7 +104,7 @@ virtqueue_rxvq_flush(struct virtqueue *vq)
> vq->vq_used_cons_idx++;
> }
>
> - if (hw->use_simple_rx) {
> + if (hw->use_simple_rxtx) {
> while (vq->vq_free_cnt >= RTE_VIRTIO_VPMD_RX_REARM_THRESH) {
> virtio_rxq_rearm_vec(rxq);
> if (virtqueue_kick_prepare(vq))
>
> Besides, I'm not sure whether you are aware of this or not.
> But just FYI, when you want to use the vector Rx of virtio
> PMD, you need to be aware of the fact that the current
> implementation of vector Rx doesn't really follow the virtio
> spec. You can find more details in below link:
>
> http://dpdk.org/ml/archives/dev/2017-December/084101.html
>
> Best regards,
> Tiwei Bie