BWCTL is a command line client application and a scheduling and policy daemon that wraps throughput measurement tools such as
thrulay , and
nuttcp (versions prior to 1.3 only support =iperf=).
More Information: For configuration, common problems, examples etc
A typical BWCTL result looks like one of the two print outs below. The first print out shows a test run from the local host to 18.104.22.168 ('-c' stands for 'collector'). The second print out shows a test run to the localhost from 22.214.171.124 ('-s' stands for 'sender').
The read lengths are shown when the test is for received traffic. In his e-mail to Main.TobyRodwell on 28 March 2005 Stanislav Shalunov of Internet2 writes:
"The values are produced by Iperf and reproduced by BWCTL.
An Iperf server gives you several most frequent values that the read()
system call returned during a TCP test, along with the percentages of
all read() calls for which the given read() lengths accounted.
This can let you judge the efficiency of interrupt coalescence
implementations, kernel scheduling strategies and other such esoteric
applesauce. Basically, reads shorter than 8kB can put quite a bit of
load on the CPU (each read() call involves several microseconds of
context switching). If the target rate is beyond a few hundred
megabits per second, one would need to pay attention to read()
bwctlhome page: http://e2epi.internet2.edu/bwctl/
- Example: http://e2epi.internet2.edu/pipes/pmp/pmp-switch.htm
- Announcement of 1.3rc4 release candidate
- PERT KB pages on
– Main.TobyRodwell - 28 Oct 2005
-- Main.FrancoisXavierAndreu & Main.SimonMuyal - 06 Jun 2005
-- Main.SimonLeinen - 22 Apr 2008 - 07 Dec 2008