[LARTC] What is: "Consider r2q change"

[LARTC] What is: "Consider r2q change"

[Oliver Schulze L.]

Hi,
I'm getting this warning/error in /var/log/messages:

May 26 18:21:05 mail kernel: HTB: quantum of class 10010 is small. 
Consider r2q change.

Its a big deal? What should I do?

Many thanks
Oliver

-- 
Oliver Schulze L.
<oliver@samera.com.py>

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Re: [LARTC] What is: "Consider r2q change"

[gypsy]

"Oliver Schulze L." wrote:
> 
> Hi,
> I'm getting this warning/error in /var/log/messages:
> 
> May 26 18:21:05 mail kernel: HTB: quantum of class 10010 is small.
> Consider r2q change.
> 
> Its a big deal? What should I do?
> 
> Many thanks
> Oliver
> 
> --
> Oliver Schulze L.
> <oliver@samera.com.py>

If you are sure you REALLY want the rate that tc is complaining about,
you should manually set quantum, probably to 1514 (look at quantum for a
rate that does not generate this message for size hints).  htb is
telling you that the rate is a lot less than the rate of the parent;
experience says 31% or less of the parent rate generates this message.

tc class add dev eth1 parent 1:1 classid 1:30 htb rate $RATE ceil $CEIL
burst 5k quantum 1514 prio 3

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gypsy
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Re: [LARTC] What is: "Consider r2q change"

[m.innocenti]

Oliver Schulze L. ha scritto:
> I'm getting this warning/error in /var/log/messages:
> May 26 18:21:05 mail kernel: HTB: quantum of class 10010 is small. 
> Consider r2q change.
> Its a big deal? What should I do?

If I understand the source, that message occours when you have a leaf 
class whose calculated quantum (rate/r2q) is less than 1000 byte and the 
kernel set the quantum to 1000 byte.
I've read that the quantum should be bigger than the MTU so I don't 
understand why the kernel don't use a minimum quantum value bigger than 
1500. Someone has a clue?

 From kernel-source-2.6.10/net/sched/sch_htb.c
if (!hopt->quantum && cl->un.leaf.quantum < 1000) {
    printk(KERN_WARNING "HTB: quantum of class %X is small. Consider r2q 
change.\n", cl->classid);
    cl->un.leaf.quantum = 1000;



-- 
**********************************************************************
Marco Innocenti              Gruppo Infrastruttura e Sicurezza
CINECA                       phone:+39 0516171553 / fax:+39 0516132198
Via Magnanelli 6/3           e-mail: innocenti@cineca.it
40033 Casalecchio di Reno    Bologna (Italia)
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Re: [LARTC] What is: "Consider r2q change"

[Oliver Schulze L.]

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Re: [LARTC] What is: "Consider r2q change"

[Oliver Schulze L.]

Hi, yes, thats right, the problem was only with leaf classes.
Thanks for clarifyind that

Oliver

m.innocenti@cineca.it wrote:

> Oliver Schulze L. ha scritto:
>
>> I'm getting this warning/error in /var/log/messages:
>> May 26 18:21:05 mail kernel: HTB: quantum of class 10010 is small. 
>> Consider r2q change.
>> Its a big deal? What should I do?
>
>
> If I understand the source, that message occours when you have a leaf 
> class whose calculated quantum (rate/r2q) is less than 1000 byte and 
> the kernel set the quantum to 1000 byte.
> I've read that the quantum should be bigger than the MTU so I don't 
> understand why the kernel don't use a minimum quantum value bigger 
> than 1500. Someone has a clue?
>
> From kernel-source-2.6.10/net/sched/sch_htb.c
> if (!hopt->quantum && cl->un.leaf.quantum < 1000) {
>    printk(KERN_WARNING "HTB: quantum of class %X is small. Consider 
> r2q change.\n", cl->classid);
>    cl->un.leaf.quantum = 1000;
>
>
>
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