User Manual

TRex 69 / 113
- socket : 1
threads : [9, 10, 11, 12, 13, 14, 15]
This gave best results: with ~98 Gb/s TX BW and c=7, CPU utilization became ~21%! (40% with c=4)
6.2.4 Timer Wheeel section configuration
The memory section is optional. It is used when there is a need to tune the amount of memory used by TRex packet manager.
Default values (from the TRex source code), are usually good for most users. Unless you have some unusual needs, you can
eliminate this section.
6.2.5 Timer Wheel section configuration
The flow scheduler uses timer wheel to schedule flows. To tune it for a large number of flows it is possible to change the default
values. This is an advance configuration, don’t use it if you don’t know what you are doing. it can be configure in trex_cfg file
and trex traffic profile.
tw :
buckets : 1024
v
1
levels : 3
v
2
bucket_time_usec : 20.0
v
3
v
1
the number of buckets in each level, higher number will improve performance, but will reduce the maximum levels.
v
2
how many levels.
v
3
bucket time in usec. higher number will create more bursts
6.3 Command line options
--active-flows
An experimental switch to scale up or down the number of active flows. It is not accurate due to the quantization of flow
scheduler and in some cases does not work. Example: --active-flows 500000 wil set the ballpark of the active flows to be
~0.5M.
--allow-coredump
Allow creation of core dump.
--arp-refresh-period <num>
Period in seconds between sending of gratuitous ARP for our addresses. Value of 0 means ``never send``.
-c <num>
Number of hardware threads to use per interface pair. Use at least 4 for TRex 40Gbs.
TRex uses 2 threads for inner needs. Rest of the threads can be used. Maximum number here, can be number of free
threads divided by number of interface pairs.
For virtual NICs on VM, we always use one thread per interface pair.
--cfg <file name>
TRex configuration file to use. See relevant manual section for all config file options.
--checksum-offload-disable
Enable IP, TCP and UDP tx checksum offloading, using DPDK. This requires all used interfaces to support this.
--client_cfg <file>
YAML file describing clients configuration. Look here for details.