[dpdk-dev] DPDK Latency Issue

[Jun Han]

Hi all,

I measured a roundtrip latency (using Spirent traffic generator) of sending
64B packets over a 10GbE to DPDK, and DPDK does nothing but simply forward
back to the incoming port (l3fwd without any lookup code, i.e., dstport =
port_id).

However, to my surprise, the average latency was around 150 usec. (The
packet drop rate was only 0.001%, i.e., 283 packets/sec dropped) Another
test I did was to measure the latency due to sending only a single 64B
packet, and the latency I measured is ranging anywhere from 40 usec to 100
usec.

I do not understand why this is so slow. Can someone explain the reasoning
behind this phenomenon?

Thank you so much!