From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thierry Coutelier <Thierry.Coutelier@linux.lu>
Date: Thu, 05 Dec 2002 15:34:45 +0000
Subject: Re: [LARTC] CBQ or HTP accuracy
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To: lartc@vger.kernel.org


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 15=
12
> > 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=3Dmax
> > 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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