TRex Traffic Generator (TG) is used for measuring latency across 2-Node and 3-Node SUT server topologies. TRex integrates A High Dynamic Range Histogram (HDRH) code providing per packet latency distribution for latency streams sent in parallel to the main load packet streams. Packet latency is measured using following methodology:
Latency tests are performed at following packet load levels:
No-Load: latency streams only.
Low-Load: at 10% PDR.
Mid-Load: at 50% PDR.
High-Load: at 90% PDR.
NDR-Load: at 100% NDR.
PDR-Load: at 100% PDR.
Latency is measured for all tested packet sizes except IMIX due to TG restriction.
TG sends dedicated latency streams, one per direction, each at the rate of 9 kpps at the prescribed packet size; these are sent in addition to the main load streams.
TG reports Min/Avg/Max and HDRH latency values distribution per stream direction, hence two sets of latency values are reported per test case.
Reported latency values are aggregate across tested topology.
+/- 1 usec is the measurement accuracy advertised by TRex TG for the setup used.
TG setup introduces an always-on Tx/Rx interface latency of about 2 * 2 usec per direction induced by TRex SW writing and reading packet timestamps on CPU cores.