[LARTC] bandwidth control on htb

[LARTC] bandwidth control on htb

[Fatih Düzova]

Hi,
I implemented queues on some ports with htb by filtering. and to have
a constant bw, i defined rate and ceil the same. But while watching
the bw's, I ve realized they may sometimes exceed the defined value
for short periods. How could I avoid this situation? I thought that
implementing a leaky bucket'd be fine but i m not sure about this and
how to do it on tc.
I would be glad if anyone could help me. Thanks,

Fatih DUZOVA
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Re: [LARTC] bandwidth control on htb

[Andy Furniss]

Fatih Düzova wrote:
> Hi,
> I implemented queues on some ports with htb by filtering. and to have
> a constant bw, i defined rate and ceil the same. But while watching
> the bw's, I ve realized they may sometimes exceed the defined value
> for short periods.

How are you measuring this and what rates do you use?

> How could I avoid this situation? I thought that
> implementing a leaky bucket'd be fine but i m not sure about this and
> how to do it on tc.
> I would be glad if anyone could help me. Thanks,

There are a few things you can do - I don't know if you really need to.

You could specify burst 10b cburst 10b quantum 1500 on the leaf classes.

There is also a setting - HYSTERESIS in the defines in 
net/sched/sch_htb.c that when changed to 0 (need to recompile 
kernel/module) makes htb a bit more accurate - though I never noticed it 
affecting rates as such.

Andy.
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Re: [LARTC] bandwidth control on htb

[Andy Furniss]

Andy Furniss wrote:
> Fatih Düzova wrote:
> 
>> Hi,
>> I implemented queues on some ports with htb by filtering. and to have
>> a constant bw, i defined rate and ceil the same. But while watching
>> the bw's, I ve realized they may sometimes exceed the defined value
>> for short periods.
> 
> 
> How are you measuring this and what rates do you use?

If you are looking at the tc counters then it will look bursty as they 
report the enque packets/bytes not dequeue - use tcpdump to see dequeue.

Andy.
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