[LARTC] tc strange behaviour (some discoveries)

[LARTC] tc strange behaviour (some discoveries)

[Alexander Kabanov]

hi All,

seems like a kernel problem

when I do the following on kernel 2.6.12.5

tc qdisc add dev lo root handle 1: htb default 1
tc class add dev lo parent 1: classid 1:1 htb rate 512kbit ceil 1mbit

all works as expected (traffic is limited to 1mbit), but this doesn't
work the same
way on kernel 2.6.14.3, and actually only ceil has effect (in my
previous message
I mentioned "rate", but I didn't pay attention that ceil gets set
automatically to
the same value you set in "rate")

when you set ceil 128kbit, you start with 128kbit bandwidth, and it
goes up to 1mbit, if you set 1mbit, it starts with 1 mbit and goes up
to 5mbit

any comments? can someone verify? how can I debug this?

best,

--alex
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Re: [LARTC] tc strange behaviour (some discoveries)

[Andy Furniss]

Alexander Kabanov wrote:
> hi All,
> 
> seems like a kernel problem
> 
> when I do the following on kernel 2.6.12.5
> 
> tc qdisc add dev lo root handle 1: htb default 1
> tc class add dev lo parent 1: classid 1:1 htb rate 512kbit ceil 1mbit
> 
> all works as expected (traffic is limited to 1mbit), but this doesn't
> work the same
> way on kernel 2.6.14.3, and actually only ceil has effect (in my
> previous message
> I mentioned "rate", but I didn't pay attention that ceil gets set
> automatically to
> the same value you set in "rate")
> 
> when you set ceil 128kbit, you start with 128kbit bandwidth, and it
> goes up to 1mbit, if you set 1mbit, it starts with 1 mbit and goes up
> to 5mbit
> 
> any comments? can someone verify? how can I debug this?

If you put htb on an interface with a big mtu - like lo/gig eth then you 
need to specify that mtu wherever you have a rate or ceil.

Andy.
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