Re: [dpdk-users] Issue with Pktgen and OVS-DPDK

["Wiles, Keith" <keith.wiles@intel.com>]

Comments inline:
> On May 2, 2017, at 8:20 AM, Gabriel Ionescu <Gabriel.Ionescu@enea.com> wrote:
> 
> Hi,
> 
> I am using DPDK-Pktgen with an OVS bridge that has two vHost-user ports and I am seeing an issue where Pktgen does not look like it generates packets correctly.
> 
> For this setup I am using DPDK 17.02, Pktgen 3.2.8 and OVS 2.7.0.
> 
> The OVS bridge is created with:
> ovs-vsctl add-br ovsbr0 -- set bridge ovsbr0 datapath_type=netdev
> ovs-vsctl add-port ovsbr0 vhost-user1 -- set Interface vhost-user1 type=dpdkvhostuser ofport_request=1
> ovs-vsctl add-port ovsbr0 vhost-user2 -- set Interface vhost-user2 type=dpdkvhostuser ofport_request=2
> ovs-ofctl add-flow ovsbr0 in_port=1,action=output:2
> ovs-ofctl add-flow ovsbr0 in_port=2,action=output:1
> 
> DPDK-Pktgen is launched with the following command so that packets generated through port 0 are received by port 1 and viceversa:
> pktgen -c 0xF --file-prefix pktgen --no-pci \
>                                --vdev=virtio_user0,path=/tmp/vhost-user1 \
>                                --vdev=virtio_user1,path=/tmp/vhost-user2 \
>                                -- -P -m "[0:1].0, [2:3].1”

The above command line is wrong as Pktgen needs or takes the first lcore for display output and timers. I would not use -c -0xF, but -l 1-5 instead, as it is a lot easier to understand IMO. Using this option -l 1-5 you are using 5 lcores (skipping lcore 0 in a 6 lcore VM) one for Pktgen and 4 for the two ports. -m [2:3].0 -m [4:5].1 leaving lcore 1 for Pktgen to use and I am concerned you did not see some performance or lockup problem. I really need to add a test for these types of problem :-( You can just have 5 lcores for the VM, which then pktgen shares lcore 0 with Linux using -l 0-4 option.

Pktgen when requested to send 64 byte frames it sends 60 byte payload + 4 byte Frame Checksum. This does work and it must be in how vhost-user is testing for the packet size. In the mbuf you have payload size and the buffer size. The Buffer size could be 1524, but the payload or frame size will be 60 bytes as the 4 bytes FCS is appended to the frame by the hardware. It seems to me that vhost-user is not looking at the correct struct rte_mbuf member variable in its testing.

> 
> In Pktgen, the default settings are used for both ports:
> 
> -          Tx Count: Forever
> 
> -          Rate: 100%
> 
> -          PktSize: 64
> 
> -          Tx Burst: 32
> 
> Whenever I start generating packets through one of the ports (in this example port 0 by running start 0), the OVS logs throw warnings similar to:
> 2017-05-02T09:23:04.741Z|00022|netdev_dpdk(pmd9)|WARN|Dropped 1194956 log messages in last 49 seconds (most recently, 41 seconds ago) due to excessive rate
> 2017-05-02T09:23:04.741Z|00023|netdev_dpdk(pmd9)|WARN|vhost-user2: Too big size 1524 max_packet_len 1518
> 2017-05-02T09:23:04.741Z|00024|netdev_dpdk(pmd9)|WARN|vhost-user2: Too big size 1524 max_packet_len 1518
> 2017-05-02T09:23:04.741Z|00025|netdev_dpdk(pmd9)|WARN|vhost-user2: Too big size 1524 max_packet_len 1518
> 2017-05-02T09:23:04.741Z|00026|netdev_dpdk(pmd9)|WARN|vhost-user2: Too big size 1524 max_packet_len 1518
> 2017-05-02T09:23:15.761Z|00027|netdev_dpdk(pmd9)|WARN|Dropped 1344988 log messages in last 11 seconds (most recently, 0 seconds ago) due to excessive rate
> 2017-05-02T09:23:15.761Z|00028|netdev_dpdk(pmd9)|WARN|vhost-user2: Too big size 57564 max_packet_len 1518
> Port 1 does not receive any packets.
> 
> When running Pktgen with the -socket-mem option (e.g. --socket-mem 512), the behavior is different, but with the same warnings thrown by OVS: port 1 receives some packages, but with different sizes, even though they are generated on port 0 with a 64b size:
>  Flags:Port      :   P--------------:0   P--------------:1
> Link State        :       <UP-10000-FD>       <UP-10000-FD>     ----TotalRate----
> Pkts/s Max/Rx     :                 0/0             35136/0               35136/0
>       Max/Tx     :        238144/25504                 0/0          238144/25504
> MBits/s Rx/Tx     :             0/13270                 0/0               0/13270
> Broadcast         :                   0                   0
> Multicast         :                   0                   0
>  64 Bytes        :                   0                 288
>  65-127          :                   0                1440
>  128-255         :                   0                2880
>  256-511         :                   0                6336
>  512-1023        :                   0               12096
>  1024-1518       :                   0               12096
> Runts/Jumbos      :                 0/0                 0/0
> Errors Rx/Tx      :                 0/0                 0/0
> Total Rx Pkts     :                   0               35136
>      Tx Pkts     :             1571584                   0
>      Rx MBs      :                   0                 227
>      Tx MBs      :              412777                   0
> ARP/ICMP Pkts     :                 0/0                 0/0
>                  :
> Pattern Type      :             abcd...             abcd...
> Tx Count/% Rate   :       Forever /100%       Forever /100%
> PktSize/Tx Burst  :           64 /   32           64 /   32
> Src/Dest Port     :         1234 / 5678         1234 / 5678
> Pkt Type:VLAN ID  :     IPv4 / TCP:0001     IPv4 / TCP:0001
> Dst  IP Address   :         192.168.1.1         192.168.0.1
> Src  IP Address   :      192.168.0.1/24      192.168.1.1/24
> Dst MAC Address   :   a6:71:4e:2f:ee:5d   b6:38:dd:34:b2:93
> Src MAC Address   :   b6:38:dd:34:b2:93   a6:71:4e:2f:ee:5d
> VendID/PCI Addr   :   0000:0000/00:00.0   0000:0000/00:00.0
> 
> -- Pktgen Ver: 3.2.8 (DPDK 17.02.0)  Powered by Intel(r) DPDK -------------------
> 
> If packets are generated from an external source and testpmd is used to forward traffic between the two vHost-user ports, the warnings are not thrown by the OVS bridge.
> 
> Should this setup work?
> Is this an issue or am I setting something up wrong?
> 
> Thank you,
> Gabriel Ionescu

Regards,
Keith