[LARTC] CBQ or HTP accuracy

[LARTC] CBQ or HTP accuracy

[Thierry Coutelier]

Hello,

I am rate limiting traffic going to some IP addresses using CBQ
  (and want to change to HTB sometime).

While testing with different packet sizes I found out that I could go above the
   rate limit I set. (even with HTB)

The values I use are: rate: 768kbit  weight 77kbit allot 10000 avpkt 1512
I did not change the cell or other parameters.
My root qdisc is set to 40MBit.

With those values I am able to go up to 840kbit/s with packets sizes of 612 or 1224.
With other values it's less except for very low values.

Changing the allot value (If I understood well allot*weight=max packets per round)
  it only gets worst (tested with 1000 and 50000).

AVPKT is only used for maxidle so it should not change anything ?

What values should I tweak to have the max rate never exeeded and still be able
   to come very near my max-rate using 1460 bytes packets ?

Would HTB be more accruate ?


Thanks for the HELP.

-- 
Thierry Coutelier      /'\ ASCII Ribbon Campaign
http://www.linux.lu    \ / No HTML/RTF in email
.                       ×  No Word docs in email
.                      / \ Respect for open standards


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Re: [LARTC] CBQ or HTP accuracy

[Stephane Ouellette]

Thierry Coutelier wrote:

>
>
> Hello,
>
> I am rate limiting traffic going to some IP addresses using CBQ
>  (and want to change to HTB sometime).
>
> While testing with different packet sizes I found out that I could go 
> above the
>   rate limit I set. (even with HTB)
>
> The values I use are: rate: 768kbit  weight 77kbit allot 10000 avpkt 1512
> I did not change the cell or other parameters.
> My root qdisc is set to 40MBit.
>
> With those values I am able to go up to 840kbit/s with packets sizes 
> of 612 or 1224.
> With other values it's less except for very low values.
>
> Changing the allot value (If I understood well allot*weight=max 
> packets per round)
>  it only gets worst (tested with 1000 and 50000).
>
> AVPKT is only used for maxidle so it should not change anything ?
>
> What values should I tweak to have the max rate never exeeded and 
> still be able
>   to come very near my max-rate using 1460 bytes packets ?
>
> Would HTB be more accruate ?
>
>
> Thanks for the HELP.
>
Thierry,

   to my knowledge, HTB is more predictable than CBQ and easier to set up.

   If you want more accuracy,  I suggest you modify a file in the kernel 
source:    include/net/pkt_sched.h

   Change the #define for PSCHED_CLOCK_SOURCE from PSCHED_JIFFIES to 
PSCHED_CPU.

   I've read this suggestion on the list but never tried it yet.  Note 
that this is valid only for CPUs that support a TSC (Pentium and up).

Regards,

Stephane


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Re: [LARTC] CBQ or HTP accuracy

[Thierry Coutelier]

I already tried it and it does not improve much the behaviour.

With which parameters should I play in HTB and CBQ ?


Stephane Ouellette wrote:

> Thierry Coutelier wrote:
>
> >
> >
> > Hello,
> >
> > I am rate limiting traffic going to some IP addresses using CBQ
> >  (and want to change to HTB sometime).
> >
> > While testing with different packet sizes I found out that I could go
> > above the
> >   rate limit I set. (even with HTB)
> >
> > The values I use are: rate: 768kbit  weight 77kbit allot 10000 avpkt 1512
> > I did not change the cell or other parameters.
> > My root qdisc is set to 40MBit.
> >
> > With those values I am able to go up to 840kbit/s with packets sizes
> > of 612 or 1224.
> > With other values it's less except for very low values.
> >
> > Changing the allot value (If I understood well allot*weight=max
> > packets per round)
> >  it only gets worst (tested with 1000 and 50000).
> >
> > AVPKT is only used for maxidle so it should not change anything ?
> >
> > What values should I tweak to have the max rate never exeeded and
> > still be able
> >   to come very near my max-rate using 1460 bytes packets ?
> >
> > Would HTB be more accruate ?
> >
> >
> > Thanks for the HELP.
> >
> Thierry,
>
>   to my knowledge, HTB is more predictable than CBQ and easier to set up.
>
>   If you want more accuracy,  I suggest you modify a file in the kernel
> source:    include/net/pkt_sched.h
>
>   Change the #define for PSCHED_CLOCK_SOURCE from PSCHED_JIFFIES to
> PSCHED_CPU.
>
>   I've read this suggestion on the list but never tried it yet.  Note
> that this is valid only for CPUs that support a TSC (Pentium and up).
>
> Regards,
>
> Stephane
>

-- 
Thierry Coutelier      /'\ ASCII Ribbon Campaign
http://www.linux.lu    \ / No HTML/RTF in email
.                       ×  No Word docs in email
.                      / \ Respect for open standards


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