----- Original Message -----
Sent: Tuesday,
November 12, 2002 9:57 AM
Subject:
Extremely inaccurate results using either TBF or HTB
Hi everyone,
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?
Thank you very much for any help
you can provide!
Dan Farino
Sr.
System Engineer
Stamps.com,
Inc.
Santa
Monica, CA
