> > I am getting extremely inaccurate results from my setup: > > - RedHat 8.0 on a Compaq ProLiant 1600, dual PII/450, Intel Dual 100 NIC > - I've tried both SMP and non-SMP kernels. > - I'm using the updated tc from the HTB home page. > - I'm using the HTB that comes with the RH8 kernel. > > Here's what's happening. If I, for instance: > > tc qdisc add dev eth2 root tbf rate 1.9mbit buffer 20Kb/8 limit > 15Kb > > Then my download rate goes at 360,000 bytes/s, which, by my > calculations, is 2.77mbit. I am using Win2k perfmon to test the speed. > The line is flat and the speed is very consistent (consistently *wrong*, > unfortunately...) > > Immediately after, I do: > > tc qdisc change dev eth2 root tbf rate 1.8mbit buffer 20Kb/8 limit > 15Kb > > My download speed is then 243,000 bytes/s, or 1.85mbit. Again, very > flat, consistent line. > > > I have played with the parameters on both TBF and HTB in many different > configurations. I always seem to have a large jump between 1.8-1.9. I > can't find any number between those two that will actually produce a > 2mbit limit. I know 1.85 is close to 2.0, but is this the expected > margin of error? (Then again, 2.77 isn't close to 1.9 at all, so I hope > not!) > > Has anyone else experienced anything like this? I did some tests with htb and tbf : http://www.docum.org/stef.coene/qos/tests/tbf/ http://www.docum.org/stef.coene/qos/tests/htb/index.html And the accuracy was very good. I did the tests on a debian system with a custom kernel and tc command. How did you measure the throughput? I use the iptables counters so I know exactly what passes the box. If you download a file from the internet with a ftp client, there can be overhead due to retransmission, control packets, .... So the speed you measure with the ftp client may be lower then the real connection speed. Stef -- stef.coene@docum.org "Using Linux as bandwidth manager" http://www.docum.org/ #lartc @ irc.oftc.net _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
