I am getting "hw csum failure" messages with sky2. I have seen this
problem reported elsewhere with a fibre NIC, but I am using a copper
NIC. It seems to be triggered by SMP. It is easy to reproduce in
2.6.23. 2.6.24-rc2-git3 still has the problem, but it happens less
frequently.
To reproduce the problem, I am using a simple network benchmark program
that I wrote that basically does send()/recv() as fast as possible using
a memory buffer (null data, no disk I/O, no data integrity checking).
The computer with the SysKonnect NIC acts as the server. I have two
other computers with Intel PRO/1000 NICs that are directly cabled to the
two ports on the SysKonnect NIC. Each of them runs the client program,
which connects to the server, send()s 10 GB, and then recv()s 10 GB.
Essentially, both ports on the Syskonnect NIC are receiving at the
maximum rate for a few minutes, and then transmitting at the maximum
rate for a few minutes. Sustained throughput is about 117 MB/s on both
ports simultaneously.
The "hw csum failure" does not seem to affect the test. send()/recv()
continue to work normally. Nothing locks up.
I get several "hw csum failure" messages per minute on 2.6.23-SMP. The
error does not happen with 2.6.23 if I boot with "max_cpus=1". The
message seems less frequent with 2.6.24-SMP, but it still happens once
every minute or so.
The "hw csum failure" message does not happen when only one port is in
use. You have to stress both ports simultaneously to reproduce the
problem.
Another cosmetic issue is that "ifconfig" shows eth2 at IRQ 16 and eth3
at IRQ 218, when in fact both are at IRQ 218. IRQ 16 is the regular
interrupt line and IRQ 218 is the MSI interrupt. I imagine that the
driver is just reporting the IRQ incorrectly in this case. It is just a
minor cosmetic issue which doesn't break anything.
Let me know if I can be of any further assistance in tracking down this
problem.
NIC: Syskonnect SK-9E22 dual-port copper PCI-express
motherboard: SuperMicro ...
