Re: Unable to get RSS to work in testpmd and load balancing question

The problem appears to be that rxmode.mq_mode was never set to ETH_MQ_RX_RSS in testpmd.c; it’s initialized to 0. There should probably be a configuration for that, or should be set when rxq > 1. 

Dan

On Jan 8, 2014, at 3:24 PM, Dan Kan [off-list ref] wrote:

I'm evaluating DPDK using dpdk-1.5.1r1. I have been playing around with the test-pmd sample app. I'm having a hard time to get RSS to work. I have a 2-port 82599 Intel X540-DA2 NIC. I'm running the following command to start the app.

sudo ./testpmd -c 0x1f -n 2 -- -i --portmask=0x3 --nb-cores=4 --rxq=4 --txq=4

I have a packet generator that sends udp packets with various src IP. According testpmd, I'm only receiving packets in port 0's queue 0. Packets are not going into any other queues. I have attached the output from testpmd.


  ------- Forward Stats for RX Port= 0/Queue= 0 -> TX Port= 1/Queue= 0 -------
  RX-packets: 1000000        TX-packets: 1000000        TX-dropped: 0             
  ---------------------- Forward statistics for port 0  ----------------------
  RX-packets: 1000000        RX-dropped: 0             RX-total: 1000000
  TX-packets: 0              TX-dropped: 0             TX-total: 0
  ----------------------------------------------------------------------------

  ---------------------- Forward statistics for port 1  ----------------------
  RX-packets: 0              RX-dropped: 0             RX-total: 0
  TX-packets: 1000000        TX-dropped: 0             TX-total: 1000000
  ----------------------------------------------------------------------------

  +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
  RX-packets: 1000000        RX-dropped: 0             RX-total: 1000000
  TX-packets: 1000000        TX-dropped: 0             TX-total: 1000000
  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

On a separate note, I also find that the CPU utilization using 1 forwarding core for 2 ports seems to be better (in the aggregate sense) than using 2 forwarding cores for 2 ports. Running at 10gbps line rate of pktlen=400, with 1 core, the core's utilization is 40%. With 2 cores, each core's utilization would 30%, giving an aggregate of 60%.

I have a use case of only doing rxonly packet processing. From my initial test, it seems that it's more efficient to have a single core read packets from both ports, and distribute the packet using rte_ring instead of having each core read from its port. The rte_eth_rx operations appear to be much CPU intensive than rte_ring_dequeue operations. 

Thanks in advance.

Dan