[dpdk-dev] [PATCH v2 6/8] net/virtio: support IN_ORDER Rx and Tx
Liu, Yong
yong.liu at intel.com
Wed Jun 27 16:27:41 CEST 2018
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin at redhat.com]
> Sent: Wednesday, June 27, 2018 4:18 PM
> To: Liu, Yong <yong.liu at intel.com>; Bie, Tiwei <tiwei.bie at intel.com>
> Cc: Wang, Zhihong <zhihong.wang at intel.com>; dev at dpdk.org
> Subject: Re: [PATCH v2 6/8] net/virtio: support IN_ORDER Rx and Tx
>
>
>
> On 06/25/2018 05:17 PM, Marvin Liu wrote:
> > IN_ORDER Rx function can support merge-able feature. Descriptors
> My understanding of the code is that IN_ORDER Rx function only supports
> mergeable feature (and it seems to be confirmed by patch 7).
>
> So maybe change the text to:
> "IN_ORDER Rx function requires merge-able feature."
Thanks for point out this, Rx function choice was depended on merge-able feature. Will change comment in next release.
>
> > allocation and free will be done in bulk.
> >
> > Virtio dequeue logic:
> > dequeue_burst_rx(burst mbufs)
> > for (each mbuf b) {
> > if (b need merge) {
> > merge remained mbufs
> > add merged mbuf to return mbufs list
> > } else {
> > add mbuf to return mbufs list
> > }
> > }
> > if (last mbuf c need merge) {
> > dequeue_burst_rx(required mbufs)
> > merge last mbuf c
> > }
> > refill_avail_ring_bulk()
> > update_avail_ring()
> > return mbufs list
> >
> > IN_ORDER Tx function can support offloading features. Packets can't be
> s/can support/supports/
>
> > transmitted by IN_ORDER Tx will be handled by normal Tx.
>
> Can you clarify why some packets can't be transmitted by IN_ORDER Tx?
My previous description may not clear, all Tx descriptors will be saved to avail ring in-order.
For making code clean, packets which matched "can_push" option will be handled by simple xmit inorder function.
Those packets can't match "can_push" will be handled one by one by previous xmit function.
Thanks,
Marvin
>
> > Virtio enqueue logic:
> > xmit_cleanup(used descs)
> > for (each xmit mbuf b) {
> > if (b can inorder xmit) {
> > add mbuf b to inorder burst list
> > continue
> > } else {
> > xmit inorder burst list
> > xmit mbuf b with normal xmit
> > }
> > }
> > if (inorder burst list not empty) {
> > xmit inorder burst list
> > }
> > update_avail_ring()
> >
> > Signed-off-by: Marvin Liu <yong.liu at intel.com>
> >
>
>
> Other than above clarification needed, the code looks good to me.
>
> Thanks,
> Maxime
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