Traffic shaping with Generic Receive Offload

I found an issue on my firewall: traffic shaping reduces download speed. I tracked it down to GRO on my ethernet board and I’d like to confirm my problems on other systems.
Could you please follow the steps in issue 3241 and post your findings?

Thank you.

I confirmed my findings on a different system.

Please, anyone could confirm my findings?
I tested some adsl lines here in Italy, but I can’t reproduce the problem.
The only two systems where I found the slow down share a fast fiber line.

The basic test is:

  1. do a speed test and record performances with traffic shaping
  2. repeat with traffic shaping set to a much higher bandwidth limit then real (i.e. set to 100000 kbps)

Results in 2. shoud be much lower then real speed. In my tests, I had 30mbit in 1 and less than 1mbit in 2.