Re: [dpdk-dev] [PATCH v2 3/4] app/testpmd: fix packet header in txonly mode

[Chengchang Tang <tangchengchang@huawei.com>]

On 2020/9/15 0:23, Ferruh Yigit wrote:
> On 8/20/2020 2:42 AM, Wei Hu (Xavier) wrote:
>> From: Chengchang Tang <tangchengchang@huawei.com>
>>
>> In txonly forward mode, the packet header is fixed by the initial
>> setting, including the packet length and checksum. So when the packets
>> varies, this may cause a packet header error. Currently, there are two
>> methods in txonly mode to randomly change the packets.
>> 1. Set txsplit random and txpkts (x[,y]*), the number of segments
>>    each packets will be a random value between 1 and total number of
>>    segments determined by txpkts settings.
>>    The step as follows:
>>      a) ./testpmd -w xxx -l xx -n 4 -- -i --rxd xxxx --txd xxxx
>>      b) set fwd txonly
>>      c) set txsplit rand
>>      d) set txpkts 2048,2048,2048,2048
>>      e) start
>> The nb_segs of the packets sent by testpmd will be 1~4. The real packet
>> length will be 2048, 4096, 6144 and 8192. But in fact the packet length
>> in ip header and udp header will be fixed by 8178 and 8158.
> 
> Although I confirm the patch fixes the ip & udp header packet size for
> "txsplit=rand" config,
> I am always getting actual packet size wrong, independent from
> 'txsplit', and it is always first segment size. Am I doing something wrong?

Yes, I miss it. If the txsplit is not set and the txpkts is set, the txonly
fwd engine will only send single segment packets, and there will be a payload
error for the data_len will be refreshed by the sum of the segment size.

May be the data_len should be the first segment size if the txsplit is not set?
I will fix it in the next version.
> 
> And not related to this patch but why setting 'txpkts' requires "--rxd
> xxxx --txd xxxx" options explicitly set? If you are already there can
> you also remove this restriction?

OK, I will fix it in next version.
> <...> 
> .
>