4 TRex Traffic Generator (TG) is used for measuring latency of VPP DUTs.
5 Reported latency values are measured using following methodology:
7 - Latency tests are performed at 100% of discovered NDR and PDR rates
8 for each throughput test and packet size (except IMIX).
9 - TG sends dedicated latency streams, one per direction, each at the
10 rate of 9 kpps at the prescribed packet size; these are sent in
11 addition to the main load streams.
12 - TG reports min/avg/max latency values per stream direction, hence two
13 sets of latency values are reported per test case; future release of
14 TRex is expected to report latency percentiles.
15 - Reported latency values are aggregate across two SUTs if the three
16 node topology is used for given performance test; for per SUT latency,
17 reported value should be divided by two.
18 - 1usec is the measurement accuracy advertised by TRex TG for the setup
19 used in FD.io labs used by CSIT project.
20 - TRex setup introduces an always-on error of about 2*2usec per latency
21 flow additonal Tx/Rx interface latency induced by TRex SW writing and
22 reading packet timestamps on CPU cores without HW acceleration on NICs
23 closer to the interface line.