Hello,

Besides a very good functionality, I have a small, yet stressing, problem.

Let's say I have a bandwidth of N bits.

I have X clients, everyone with his fixed bandwidth.

I create htb qdsics for each client. Each leaf has sfq queueing
discipline.

A sample config would be like this :

tc class add dev eth0 parent 1:2 classid 1:346 htb rate 32Kbit ceil 32Kbit
   burst 4k cburst 2k prio 4
tc qdisc add dev eth0 parent 1:346 handle 346 sfq perturb 10

AND

tc class add dev eth0 parent 1:2 classid 1:161 htb rate 256Kbit ceil
   256Kbit burst 32k cburst 2k prio 4
tc qdisc add dev eth0 parent 1:161 handle 161 sfq perturb 10


The filters are like :
tc filter add dev eth0 parent 1:0 protocol ip prio 100 u32 match ip dst
1.2.3.128/25 classid 1:346
tc filter add dev eth0 parent 1:0 protocol ip prio 100 u32 match ip dst
1.2.3.4/30 classid 1:161

The problem is that clients can have their bandwidths at maximum only if
they use a download accelerating software like DAP with multiple
symultanous threads. Using only one thread, a single download can reach
about 60% of the allocated bandwidth.

I have tested a download without any limits and it was working well, so
there's no problem with the remote site.

I have searched thorugh messages posted on this mailing list but I didn't
find a similar problem.


Maybe I need to set quantum manually. I have tested with r2q default value
(10) and also with 2 (raising quantum).

Another question would be: if quantum is bigger, the client can exceed his
limit by that value ? Is that possible all the time or at bursty intervals
?


Thank you very much,
Ciprian Nica

On Wednesday 28 August 2002 15:15, Ciprian Nica wrote:
> Hello,
>
> Besides a very good functionality, I have a small, yet stressing, probl=
em.
>
> Let's say I have a bandwidth of N bits.
>
> I have X clients, everyone with his fixed bandwidth.
>
> I create htb qdsics for each client. Each leaf has sfq queueing
> discipline.
>
> A sample config would be like this :
>
> tc class add dev eth0 parent 1:2 classid 1:346 htb rate 32Kbit ceil 32K=
bit
>    burst 4k cburst 2k prio 4
> tc qdisc add dev eth0 parent 1:346 handle 346 sfq perturb 10
>
> AND
>
> tc class add dev eth0 parent 1:2 classid 1:161 htb rate 256Kbit ceil
>    256Kbit burst 32k cburst 2k prio 4
> tc qdisc add dev eth0 parent 1:161 handle 161 sfq perturb 10
>
>
> The filters are like :
> tc filter add dev eth0 parent 1:0 protocol ip prio 100 u32 match ip dst
> 1.2.3.128/25 classid 1:346 tc filter add dev eth0 parent 1:0 protocol i=
p
> prio 100 u32 match ip dst 1.2.3.4/30 classid 1:161
>
> The problem is that clients can have their bandwidths at maximum only i=
f
> they use a download accelerating software like DAP with multiple
> symultanous threads. Using only one thread, a single download can reach
> about 60% of the allocated bandwidth.
>
> I have tested a download without any limits and it was working well, so
> there's no problem with the remote site.
>
> I have searched thorugh messages posted on this mailing list but I didn=
't
> find a similar problem.
>
>
> Maybe I need to set quantum manually. I have tested with r2q default va=
lue
> (10) and also with 2 (raising quantum).
>
> Another question would be: if quantum is bigger, the client can exceed =
his
> limit by that value ? Is that possible all the time or at bursty interv=
als
> ?
Quantum is used if 2 or more classes with the same parent are fighting fo=
r=20
bandwidth.  First, they are allowed to get the rate you gave them.  For t=
he=20
remaining bandwidth, quantum is used.  Each class may send quantum bytes.=
 =20
You have to make sure quantum > MTU (typical 1500 bytes for ethernet).

What if you use no sfq qdiscs?

Stef


--=20

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net

On Wednesday 28 August 2002 20:45, Stef Coene wrote:

> > The problem is that clients can have their bandwidths at maximum only
if
> > they use a download accelerating software like DAP with multiple
> > symultanous threads. Using only one thread, a single download can
reach
> > about 60% of the allocated bandwidth.
>
> Quantum is used if 2 or more classes with the same parent are fighting for
> bandwidth.  First, they are allowed to get the rate you gave them.  For the
> remaining bandwidth, quantum is used.  Each class may send quantum bytes.
> You have to make sure quantum > MTU (typical 1500 bytes for ethernet).
>
> What if you use no sfq qdiscs?
>
> Stef

I have tried with pfifo queues and it's the same. I made many tests changing
quantum, queueing for leaf but in no case I could reach the allocated
bandwidth with a single download thread. The same limit set on cisco router
with traffic-shape, worked fine.

Could there be a problem when there are many qdiscs ? Are there many
calculations to be done, so the packets get delayed and the TCP transfer rate
is lowered.

Ciprian