[LARTC] HTB traffic shaping odd effects

[Andy Furniss]

Oliver Hookins wrote:
> Denis Ovsienko wrote:
> 
>>> tc qdisc add dev eth0 root handle 1: htb default 10
>>> tc class add dev eth0 parent 1: classid 1:1 htb rate 100mbit burst 24k
>>
>>
>> Does the following help?
>> tc qdisc add dev eth0 root handle 1: htb default 1
>> tc class add dev eth0 parent 1: classid 1:1 htb rate 81mbit burst 24k
> 
> 
> That seems a bit backward, limiting the total available bandwidth to 
> enforce child class limits. Or is that how htb works, that the sum of 
> the child classes must add up to no less than the parent class?
> 
> In any case we have 100mbit available so I don't want to set it any 
> lower than that, if possible.
> 

You haven't got 100mbit once overheads are accounted for and in this 
test using 81 instead of 100 won't affect your bandwidth as all traffic 
is going to one of the two sub classes. I have IIRC spotted differences 
(to do with quantum and sharing excess) when parent is > than ceils - it 
wasn't the same setup as yours though.

Andy.