Help with the latency test of DPDK

[shengkai16]

Hi XDP team,

I'm attempting to use the method you have provided to test the DPDK latency between our Mellanox NICs. But unfortunately, I cannot recurrence the DPDK latency as small as 2us as you have said in your paper. In contrast, we get the DPDK latency which is 7us - 10us on average.

Testbed Configuration
HCA: Mellanox BlueField-2 MT41686
Linux version: Ubuntu 18.04.1 LTS
OFED version: MLNX_OFED_LINUX-5.3-1.0.5.0
DPDK version: 20.11.3
T-rex version: v2.92

Test method
I just followed the instruction you have provided: use T-rex on one of the server to generate packets and start testpmd app of DPDK on the other server. I have tested the latency under 10, 1k, 1M pps situations.
But because of our hardware limitation, We can only connect one link between two servers. So we had to use a dummy port in T-rex configuration.

Latency result from T-rex:
1k pps

1Mpps

I would be very graceful for any help on there problems. Thank you!

Jeff

[tohojo]

Hmm, to get the exact same performance numbers you'll probably need identical hardware. No idea why it would differ on your machine, but it could be anything from the NIC slowing things down, to the host CPU having different caching behaviour, to the fact that you're only using a single NIC... And I'm by no means a DPDK expert, so couldn't really tell you what you need to tune either.

[shengkai16]

Hmmmm, I got that. Maybe I should try to use two links between servers firstly... Thank you anyway!