[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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