Re: [LARTC] HTB doesn't respect rate values

Linux Advanced Routing and Traffic Control

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> I did pfifo with limit 10 and HTB started to work. I noticed drops and
> rate was OK. Sometimes (for 10-40 seconds) but seldom it worked bad (1:2
> got less, than it should) but there wasn't drops during this time. I
> tried this also with 12kbit at it was similar.
>
> If I good understand, there is something (TCP stack or what) whitch
> works BEVORE htb and this makes some connections slower or faster, so
> HTB has later nothing to do.
>
> The question for me is: how can I set it (the mechanism bevore HTB) to
> give HTB full control over the bandwitch? I don't wont to use pfifo (not
> everywhere). I would like to use sfq for some classes.

you can try to play with /proc/sys/net/ipv4/tcp_{w,r,}mem. If wmem is
smaller than space in qdisc (15kB for 10 pfifo, approx 200kB for SFQ)
then TCP will back off before it fill the qdisc...
Also with sfq it should work - it is like pfifo with limit 128 - you
might need to increase wmem.
Note that the problem occur only when you have qdisc on the same machine
as sending app.

devik

> Should I set specific parameter somewhere or set something in network
> configuration, or maybe recompile the kernel with a specific option?
>
> Sergiusz
>
> Użytkownik devik napisał:
> > Interestingly from what I see HTB didn't come into play.
> > All drop and overlimits counters are zero. It seems that
> > www server haven't managed to send more.
> > Please try to add pfifo with limit 10 under both classes.
> > Because you are sending from the same computer, your
> > TCP stack uses send queue management which counts packets
> > in qdisc and backs off. It MIGHT cause problems ...
> >
> > -------------------------------
> >     Martin Devera aka devik
> > Linux kernel QoS/HTB maintainer
> >   http://luxik.cdi.cz/~devik/
> >
> > On Sat, 5 Jul 2003, Sergiusz Brzeziński wrote:
> >
> >
> >>Thak you for your hints!
> >>
> >> > 1) 6kbit is really too small it should be at least 10 ..
> >>
> >>I tried with 12, 20 and even with 30kbit for 1:3
> >>
> >>I noticed, that it work for some seconds (or 1-2 minutes) but than the
> >>1:3 class gets more then it should get :(.
> >>
> >>
> >> > 2) it should workeven with 6k:
> >> >  - look at stats (tc -s class show dev eth0) before and
> >> >    after the test - you are interested in drops. Also try
> >> >    it during the test to look whether queues are build up.
> >> >
> >>
> >>I made a test with settings:
> >>---------------------------------
> >>
> >>tc qdisc del root dev eth0
> >>tc qdisc add dev eth0 root handle 1:0 htb default 3
> >>
> >>tc class add dev eth0 parent 1:0 classid 1:1 htb rate 128kbit ceil
> >>128kbit burst 20kbit
> >>
> >>tc class add dev eth0 parent 1:1 classid 1:2 htb rate 98kbit ceil
> >>128kbit quantum 4900 burst 20kbit
> >>
> >>tc class add dev eth0 parent 1:1 classid 1:3 htb rate 30kbit ceil
> >>128kbit quantum 1500
> >>
> >>tc filter add dev eth0 protocol ip parent 1:0 prio 1 u32 match ip sport
> >>80 0xffff flowid 1:2
> >>
> >>Bevore test: (reseted htb)
> >>--------------------------------
> >># tc -s class show dev eth0
> >>
> >>class htb 1:1 root rate 128Kbit ceil 128Kbit burst 2559b cburst 1762b
> >>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
> >>  lended: 0 borrowed: 0 giants: 0
> >>  tokens: 244140 ctokens: 168131
> >>
> >>class htb 1:2 parent 1:1 prio 0 rate 98Kbit ceil 128Kbit burst 2559b
> >>cburst 1762b
> >>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
> >>  lended: 0 borrowed: 0 giants: 0
> >>  tokens: 318876 ctokens: 168131
> >>
> >>class htb 1:3 parent 1:1 prio 0 rate 30Kbit ceil 128Kbit burst 1637b
> >>cburst 1762b
> >>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
> >>  lended: 0 borrowed: 0 giants: 0
> >>  tokens: 666503 ctokens: 168131
> >>
> >>After test:
> >>------------
> >>class htb 1:1 root rate 128Kbit ceil 128Kbit burst 2559b cburst 1762b
> >>  Sent 5843869 bytes 4715 pkts (dropped 0, overlimits 0)
> >>  rate 15427bps 12pps
> >>  lended: 1461 borrowed: 0 giants: 0
> >>  tokens: -21142 ctokens: -97151
> >>
> >>class htb 1:2 parent 1:1 prio 0 rate 98Kbit ceil 128Kbit burst 2559b
> >>cburst 1762b
> >>  Sent 2735702 bytes 1811 pkts (dropped 0, overlimits 0)
> >>  rate 6397bps 4pps
> >>  lended: 1802 borrowed: 9 giants: 0
> >>  tokens: 312898 ctokens: 163555
> >>
> >>class htb 1:3 parent 1:1 prio 0 rate 30Kbit ceil 128Kbit burst 1637b
> >>cburst 1762b
> >>  Sent 3108167 bytes 2904 pkts (dropped 0, overlimits 0)
> >>  rate 9488bps 8pps
> >>  lended: 1452 borrowed: 1452 giants: 0
> >>  tokens: -561135 ctokens: -97151
> >>
> >>Description of the test:
> >>------------------------
> >>On the beginning it was everything OK, after 1 min, 1:2 lost his 98kbit.
> >>Than he got sometimes his 98kbit again and sometimes he got even 30kbit.
> >>
> >>
> >>1. Can I do something more to find out what happen?
> >>2. What does mean: "queues are build up" ?
> >>
> >>Sergiusz
> >>
>
>
>




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