On Wed, 31 Oct 2018 10:29:38 +0200
"Nikos Anastopoulos" <[email protected]> wrote:

> Hi list, 
> 
>  
> 
> The TRex traffic generator's folks recommended us to contact you for an issue 
> that might relate to DPDK virtio driver 
> (https://groups.google.com/forum/#!topic/trex-tgn/LxtTV7G43AE). 
> 
>  
> 
> Specifically, our scenario involves running TRex inside a KVM instance with 2 
> vhost-user ports, which are connected in loopback mode via an OVS-DPDK (i.e. 
> whatever sent through port1 goes to port2, and vice versa). We observe that 
> the received traffic volume reported by TRex is much less than the 
> transmitted (it is constantly 4B per packet), whereas:
> 
> 1) the count of the received packets is the same
> 
> 2) the contents of the received packets, as captured _inside_ the VM, are the 
> same with the transmitted
> 
>  
> 
> Specifically, we experimented with different packet sizes being transmitted, 
> i.e. 64B, 150B, 1000B, yet in the receive path the reported incoming volume 
> corresponded constantly to 4B-per-packet, for all cases. 
> 
>  
> 
> The TRex engineers suggested that it seems like an RX counters issues in 
> virtio driver. 
> 
>  
> 
> Experimental setup: 
> 
> - TRex v2.45 (uses DPDK 17.11 AFAIK), within a QEMU v2.12
> 
> - on the host: OVS 2.10.0 with DPDK 17.11.3
> 
>  
> 
> Thanks,
> 
> Niko

No idea, try dumping a sample of packets in virtio_update_packet_stats

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