[dpdk-dev] [PATCH v2 6/8] net/virtio: support IN_ORDER Rx and Tx

Maxime Coquelin maxime.coquelin at redhat.com
Wed Jun 27 16:32:44 CEST 2018



On 06/27/2018 04:27 PM, Liu, Yong wrote:
> 
> 
>> -----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! Sounds good with above clarification.

Maxime
> 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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