[LARTC] HTB Quatum values

[LARTC] HTB Quatum values

[Damion de Soto]

Hi guys,

I've just been playing and reading again, and come to the conclusion
that although i've read a lot about quantum (& r2q) settings for the
htb qdisc, i still don't understand it.

If the quantum for each class should be as small as possible, but
larger than the MTU, then is there any reason I shouldn't always
set it to the MTU size ?

If 2 classes are fulfulling their rate and you want them to share unequally, instead 
of making the quantums different of each one, why not just change the prio ?

regards,

-- 
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Damion de Soto - Software Engineer  email:     damion@snapgear.com
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Re: [LARTC] HTB Quatum values

[Stef Coene]

On Friday 20 February 2004 06:18, Damion de Soto wrote:
> Hi guys,
>
> I've just been playing and reading again, and come to the conclusion
> that although i've read a lot about quantum (& r2q) settings for the
> htb qdisc, i still don't understand it.
>
> If the quantum for each class should be as small as possible, but
> larger than the MTU, then is there any reason I shouldn't always
> set it to the MTU size ?
Yes.  Each class will be able to send quantum bytes.  If quantum is too low, 
the classes are maybe not able to send enough packets because the polling 
frequency is not high enough.

> If 2 classes are fulfulling their rate and you want them to share
> unequally, instead of making the quantums different of each one, why not
> just change the prio ?
The prio does 2 things :
   - a low prio class will have low latency if this class is not overlimited, 
but if this class is overlimited, the latency can be very high
   - a low prio class will have a higher priority to borrow tokens from the 
parent class

Stef

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