[Click] Bidirectional Performance Issues

[Dietmar Tölle]

Hello altogether,

 

We're trying to set up a switch/router using Click with high performance, but we have trouble with bidirectional traffic and the polling drivers.

 

First of all: Our system

Pentium D830 + 2GB RAM

Mainboard with Intel 975X Chipset and 2 PCI-X interfaces

2 Intel Pro/1000 MT Dual Port Server Cards for PCI-X (82546GB chipset)

 

Click: Standard-version 1.5.0 from the Web

E1000 driver 5.7, which is included in the package, compiled with NAPI-option

Patched linux kernel 2.6.16.13

 

Click-script: Just a simple cross-connect across the 2 cards over the PCI-X bus (one card in, the other card out, and vice versa)

PollDevice(eth2, PROMISC true, BURST 32) -> Queue(100) -> ToDevice(eth5, BURST 16);

PollDevice(eth5, PROMISC true, BURST 32) -> Queue(100) -> ToDevice(eth2, BURST 16);

 

Using this script the performance is as follows:

 

Unidirectional traffic:

With max. packet size, we achieve about 1 gbps (75 kpps)

 

Bidirectional traffic:

With max. packet size, we achieve about 600 mbps (50 kpps) per direction

With min. packet size, throughput drops to 15 mbps (30 kpps) per direction

 

And the strangest fact of all: FromDevice performs EVEN BETTER than PollDevice (about 5-10%)???

 

We tried to tweak the parameter in the script (BURST) and the e1000 parameters (IntDelay, Descriptors, etc.), but it seems to have no effect at all!

 

Did anyone come across similar problems or can give us any recommendations?

Does this problem arise from the PCI-bus?

 

Thanks in advance!

 

Best regards,

Dietmar