Re: [LARTC] has anyone tried adsl-optmizer kernel patches for dsl

[Andy Furniss <andy.furniss@dsl.pipex.com>]

Markus Schulz wrote:
> On Wednesday 16 November 2005 16:03, Andy Furniss wrote:
> 
>>sophana wrote:
>>
>>>Hi
>>>
>>>I'm using wondershaper like script. But noticed imperfect
>>>scheduling.
>>>
>>>By googling, I found some patches that takes the aal5 atm overhead
>>>in the scheduling algorithms.
>>>http://www.adsl-optimizer.dk/ADSL-optimizer/
>>>
>>>Before trying it, has anyone tried these patches? they apply on
>>>2.4.29 kernel and 2.6.9 TC. I use centos4 with a 2.6 kernel, so I
>>>can't try these easily.
>>
>>They should be OK as long as you are sure about your overheads.
>>
>>I use something similar and use ceil 286kbit while synced at 288kbit
>>without problems.
>>
>>If your modem is connected by eth rather than ppp then htb/whatever
>>will see the packet size as ip len + 14 - so you need to account for
>>that.
> 
> 
> can you explain this a bit more please?

It's because htb uses skb->len for packet size and if you shape on an 
eth interface this is ip length + 14, but it's just ip length if you 
shape on ppp/vlan etc.

You can see this by looking at htb counters and sending fixed size packets.

> 
> 
>>I think that produces a corner case (overhead < 14) where you would
>>need to put in a negative number - I don't think that will work, but
>>haven't tried.
> 
> 
> should be easy to patch in. Overhead is only a simple variable which 
> will be added in htb/* module for each paket. Only sign/unsign problem  
> should be considered.

Yep  - you just need to be aware of it and I can't recall it being 
mentioned in the thesis - I have only tested on 2.6 kernels.

Andy.
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