[LARTC] why can not turn the bandwidth knob up to 100Mbit

[Rune Kock]

> (using "tc -s class show dev eth1" to list result,if the rate of class 1:21
> is 100Mbit,the result is between 99M and 100M;
> if the rate of class 1:21 is 150Mbit ,the result is between 45M and 50M;)

I wonder if this has something to do with what devik writes on the htb homepage:

<qoute>
Limitation: when you operate with high rates on computer with low
resolution timer you need some minimal burst and cburst to be set for
all classes. Timer resolution on i386 systems is 10ms and 1ms on
Alphas. The minimal burst can be computed as
max_rate*timer_resolution. So that for 10Mbit on plain i386 you needs
burst 12kb.

If you set too small burst you will encounter smaller rate than you
set. Latest tc tool will compute and set the smallest possible burst
when it is not specified.
</quote>