[LARTC] tbf latency problems!

[LARTC] tbf latency problems!

[Alaios]

Hi i have found a problem related with tbf and the
latency that the tbf calculates.. I have used the
following parameters for burst and limit
burst 100Kbit limit 500Kbit  lat81.8ms
burst 6Kbit   limit 6Kbit    lat 0us
burst 200Kbit limit 100Kbit  lat 4294.9s

As u can see in the 3rd column the latency for 100Kbit
burst and 500Kbit limit is 81.8ms but for 200Kbit and
limit 100Kbit is 4294.9s!!! How  could be possible???
I want to find a way to caclulate the latency for a
packet entering my tbf.. What do u suggest me to do?

Ah! I use the tc -s qdisc ls dev eth1 command for the
tbf statistics



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Re: [LARTC] tbf latency problems!

[Andy Furniss]

Alaios wrote:
> Hi i have found a problem related with tbf and the
> latency that the tbf calculates.. I have used the
> following parameters for burst and limit
> burst 100Kbit limit 500Kbit  lat81.8ms
> burst 6Kbit   limit 6Kbit    lat 0us
> burst 200Kbit limit 100Kbit  lat 4294.9s

What is the full command you used to get those?

> 
> As u can see in the 3rd column the latency for 100Kbit
> burst and 500Kbit limit is 81.8ms but for 200Kbit and
> limit 100Kbit is 4294.9s!!! How  could be possible???
> I want to find a way to caclulate the latency for a
> packet entering my tbf.. What do u suggest me to do?

latency is worked out from rate and limit (you can also specify latency 
and let tbf work out limit (it approximates, though)).

> 
> Ah! I use the tc -s qdisc ls dev eth1 command for the
> tbf statistics

Could be a stats bug that is fixed now, what kernel/tc version do you use.

Andy.

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Re: [LARTC] tbf latency problems!

[Alaios]

thx for your answer... i use the 2.6.10 vanilla
kernel.. i have downloaded two weeks ago the latest
iproute2.

I have installed tbf with the following command

$tc qdisc add dev $DEV parent 2:1 tbf rate $EF_RATE
burst $EF_BURST mtu $EF_MTU limit $EF_LIMIT

and i have got the results using 
tc -s qdisc ls dev eth1

I dont really think that i have done something wrong
for taking such calculation errors for the latency...

I plan to measure  the latency  this week with the
appropriate scenario.. Tell me if u want to send you a
short description of my scenario and of  course of my
results about the limit and the latency.
Thx in advance... 
I would to contribute for the lartc... that's all

--- Andy Furniss <andy.furniss@dsl.pipex.com> wrote:
> Alaios wrote:
> > Hi i have found a problem related with tbf and the
> > latency that the tbf calculates.. I have used the
> > following parameters for burst and limit
> > burst 100Kbit limit 500Kbit  lat81.8ms
> > burst 6Kbit   limit 6Kbit    lat 0us
> > burst 200Kbit limit 100Kbit  lat 4294.9s
> 
> What is the full command you used to get those?
> 
> > 
> > As u can see in the 3rd column the latency for
> 100Kbit
> > burst and 500Kbit limit is 81.8ms but for 200Kbit
> and
> > limit 100Kbit is 4294.9s!!! How  could be
> possible???
> > I want to find a way to caclulate the latency for
> a
> > packet entering my tbf.. What do u suggest me to
> do?
> 
> latency is worked out from rate and limit (you can
> also specify latency 
> and let tbf work out limit (it approximates,
> though)).
> 
> > 
> > Ah! I use the tc -s qdisc ls dev eth1 command for
> the
> > tbf statistics
> 
> Could be a stats bug that is fixed now, what
> kernel/tc version do you use.
> 
> Andy.
> 
> 


		
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Re: [LARTC] tbf latency problems!

[Andy Furniss]

Alaios wrote:
> thx for your answer... i use the 2.6.10 vanilla
> kernel.. i have downloaded two weeks ago the latest
> iproute2.
> 
> I have installed tbf with the following command
> 
> $tc qdisc add dev $DEV parent 2:1 tbf rate $EF_RATE
> burst $EF_BURST mtu $EF_MTU limit $EF_LIMIT
> 
> and i have got the results using 
> tc -s qdisc ls dev eth1
> 

I will try if you give me all the numbers you used.

Andy.
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