[LARTC] HTB timer??

[LARTC] HTB timer??

[Lars Landmark]

Hi;
As I understand, HTB use a timer in order to calculate rate.  In addition 
it also use timer to tell whether classes are allowed to send packets or 
not.                     
Could somebody tell me how this timer is calculated??

If you have, say, a link with capacity 10MB. If you so configure using HTB
two classes with the same parent to use 5MB each with priority 0,1 and 
ceil 10MB.  What would happen if bandwidth decrease to under 5MB.  

Would the highest prio class be the only served??

Thanks in advance

Lars 
Student

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] HTB timer??

[Stef Coene]

On Wednesday 14 May 2003 11:20, Lars Landmark wrote:
> Hi;
> As I understand, HTB use a timer in order to calculate rate.  In addition
> it also use timer to tell whether classes are allowed to send packets or
> not.
> Could somebody tell me how this timer is calculated??
http://www.docum.org/stef.coene/qos/faq/cache/40.html

> If you have, say, a link with capacity 10MB. If you so configure using HTB
> two classes with the same parent to use 5MB each with priority 0,1 and
> ceil 10MB.  What would happen if bandwidth decrease to under 5MB.
>
> Would the highest prio class be the only served??
No.  Each class can send it's rate as a minimum.  Prio is only used to 
distribute remaining bandwidth and to determine the order of the classes so 
the highest priority class has the lowest delays.
If you have a 10mbit class with 2 classes of each 2mbit and prio 0 and 1.  
Each class can send 2mbit.  And the class with prio 0 can use the remaining 
6mbit.  So you have 2 classes with rate 2mbit and 8mbit.

Remember : the lower the prio, the higher the priority.

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] HTB timer??

[Lars Landmark]

On Wed, 14 May 2003, Stef Coene wrote:

> On Wednesday 14 May 2003 11:20, Lars Landmark wrote:
> > Hi;
> > As I understand, HTB use a timer in order to calculate rate.  In addition
> > it also use timer to tell whether classes are allowed to send packets or
> > not.
> > Could somebody tell me how this timer is calculated??
> http://www.docum.org/stef.coene/qos/faq/cache/40.html
> 
> > If you have, say, a link with capacity 10MB. If you so configure using HTB
> > two classes with the same parent to use 5MB each with priority 0,1 and
> > ceil 10MB.  What would happen if bandwidth decrease to under 5MB.
> >
> > Would the highest prio class be the only served??
> No.  Each class can send it's rate as a minimum.  Prio is only used to 
> distribute remaining bandwidth and to determine the order of the classes so 
> the highest priority class has the lowest delays.
> If you have a 10mbit class with 2 classes of each 2mbit and prio 0 and 1.  
> Each class can send 2mbit.  And the class with prio 0 can use the remaining 
> 6mbit.  So you have 2 classes with rate 2mbit and 8mbit.
> 
> Remember : the lower the prio, the higher the priority.
Ok, But as you say prio is used in order:
to to determine the order of the classes so the highest
priority class has the lowest delays.

As I understand this, high prio class must be placed among the first
classes in the self feed list.
So my question is, how does HTB schedule this???  Among leafs classes it
has a self feed list for each priority.
Does it place high prio class at first place, or how does it order this
list.??
I have done a test for this scenario, but the result as you say did not
end with starving low prio class.

Lars 
Student

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] HTB timer??

[Stef Coene]

> > Remember : the lower the prio, the higher the priority.
>
> Ok, But as you say prio is used in order:
> to to determine the order of the classes so the highest
> priority class has the lowest delays.
>
> As I understand this, high prio class must be placed among the first
> classes in the self feed list.
> So my question is, how does HTB schedule this???  Among leafs classes it
> has a self feed list for each priority.
> Does it place high prio class at first place, or how does it order this
> list.??
> I have done a test for this scenario, but the result as you say did not
> end with starving low prio class.
It also depends on how much data you generate in the low prio class.  If you 
generate more data then the rate, the latency will be very high.  You can 
find this on the htb homepage.
So for high latency, never send more data in the class then it's configured 
rate.

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/