tbf/htb heavily inaccurate transfer rate.

Hello group,

I got two computers, one desktop (lets call it c1)
and second which is ThinkPad R52 (lets call it c0),
with the same operating system PLD AC (PLD - PLD Linux Distribution).
I am learning tc, I utilise very simple configuration,
I have chosen just for testing purposes to limit global outgoing
transfer to 100KiB/s, I played both with tbf and htb.
My both computers are connected by 100Mbit Ethernet.

My setup:

tbf case:
tc qdisc add dev eth0 root tbf rate 100kbps burst 10kb latency 70ms peakrate 101kbps mtu 1540

htb case:
tc qdisc add dev eth0 root handle 1: htb default 10
tc class add dev eth0 parent 1:0 classid 1:10 htb rate 100kbps ceil 100kbps cburst 0

I perform test by sending files from c0 to c1 (when tc tbf/htb is run
on and only on c0), and from c1 to c0 (when tc tbf/htb is set up
on and only on c1).

Without tc both of my computers have upload transfer rate
close to 11MiB/s.

When I use tbf/htb on my desktop computer, upload transfer rate
I have measured is in the expected rate range (around 100KiB/s).
My problem is with my R52, when I use tbf upload rate about 11KiB/s,
and in case of htb transfer equals 480 KiB/s.

I do not know what can be the reason of such behavior.

Feral computer is:

IBM ThinkPad R52 Intel(R) Pentium(R) M processor 1.73GHz,
Ethernet controller: Broadcom Corporation NetXtreme BCM5751M Gigabit
Ethernet PCI Express,
1GB RAM,

For my Ethernet card on R52 I use tg3 module if that matters.

Operating system, as I have mentioned is PLD AC
with 2.6.18 kernel, I have also tried to run my test on Debian Sid
also equipped with 2.6.18 kernel.

Following the advise from Polish newsgroup I have recompiled
kernel with CONFIG_NET_SCH_CLK_GETTIMEOFDAY=y setting.
No luck this time also.

I am heavily desperate and short of ideas, any help
will be really appreciated.

I attach output from "tc -s class show dev eth0" command.
This command had been invoked after uploading 240MiB of data from c0 to
c1.

class htb 1:10 root prio 0 rate 800000bit ceil 800000bit burst 1999b cburst 1999b
Sent 166303889 bytes 21612 pkt (dropped 0, overlimits 0 requeues 0)
rate 3149Kbit 50pps backlog 0b 23p requeues 0
lended: 21589 borrowed: 0 giants: 39532
tokens: -41008 ctokens: -41008

Best regards.


--
Huginn
GCS d? s:+>: a- C++$() UB++++$ P++ L++++$ E---
W+(-) N++ o? K? w-- O M- V- PS+ PE++ Y PGP-
t--- 5-- X- R !tv b++ DI++ D+ G e* h+ !r>++ y>+

On Sun, 31 Dec 2006 18:56:54 +0000 (UTC), Marcin Konarski
<(E-Mail Removed)> wrote:

>
>Hello group,

>I am heavily desperate and short of ideas, any help
>will be really appreciated.
>
>I attach output from "tc -s class show dev eth0" command.
>This command had been invoked after uploading 240MiB of data from c0 to
>c1.
>
>class htb 1:10 root prio 0 rate 800000bit ceil 800000bit burst 1999b cburst 1999b
> Sent 166303889 bytes 21612 pkt (dropped 0, overlimits 0 requeues 0)
> rate 3149Kbit 50pps backlog 0b 23p requeues 0
> lended: 21589 borrowed: 0 giants: 39532
> tokens: -41008 ctokens: -41008

Your problem is "giants:39532".

Read LARTC, searching google for "LARTC giants". It has to do with
the gigabit ethernet. Sorry, I don't know what your solution is, but
when you run at 100BaseT but are getting giants, then you have a
configuration problem. Perhaps setting mtu ("quantum 1514") in your
htb "class" line will help.
--
buck

On Sun, 31 Dec 2006 18:22:23 -0800,
buck <(E-Mail Removed)> wrote:
>>I attach output from "tc -s class show dev eth0" command.
>>This command had been invoked after uploading 240MiB of data from c0 to
>>c1.
>>
>>class htb 1:10 root prio 0 rate 800000bit ceil 800000bit burst 1999b cburst 1999b
>> Sent 166303889 bytes 21612 pkt (dropped 0, overlimits 0 requeues 0)
>> rate 3149Kbit 50pps backlog 0b 23p requeues 0
>> lended: 21589 borrowed: 0 giants: 39532
>> tokens: -41008 ctokens: -41008
>
> Your problem is "giants:39532".
>
> Read LARTC, searching google for "LARTC giants". It has to do with
> the gigabit ethernet. Sorry, I don't know what your solution is, but
> when you run at 100BaseT but are getting giants, then you have a
> configuration problem. Perhaps setting mtu ("quantum 1514") in your
> htb "class" line will help.

Hello.

Thanks to your suggestion I have found very intresting thread
http://tiny.pl/wxw4, I have followed advise from this thread
and set my mtu to 16500, and that fixed my problem.

Thank you very much.

--
Huginn
GCS d? s:+>: a- C++$() UB++++$ P++ L++++$ E---
W+(-) N++ o? K? w-- O M- V- PS+ PE++ Y PGP-
t--- 5-- X- R !tv b++ DI++ D+ G e* h+ !r>++ y>+