[LARTC] HTB at 100+ Mbits/sec

[Jesper Dangaard Brouer]

On Fri, 12 May 2006, Muthukumar S wrote:

> <cut>
> Also I was wondering what limits (if any) the kernel timer resolution
> imposes on HTB.
> <cut>

The kernel timer resolution does have an impact on the precision of HTB 
(the delay jitter).

I have done some detailed studies in my master thesis.  Which is located 
at: http://www.adsl-optimizer.dk/thesis/.

You should look at chapter 7.
  Read section 7.3.2 "Timer Granularity" (page 71)
  and section 7.3.3 "Improving Granularity" (page 73)

Figure 7.8 (page 75), shows how the delay jitter bound is improved when 
changing the timer from HZ=100 to HZ=1500.


For the discusion about, why the you need to reduce the bandwidth to less 
that the actual bandwidth, you should look at Chapter 6 "Achieving Queue 
Control".  Especially if you have an ADSL link.

Greeting,
   Jesper Brouer

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MSc. Master of Computer Science
Dept. of Computer Science, University of Copenhagen
Author of http://www.adsl-optimizer.dk
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