Hi,

I'm bridging two network interfaces. I tested throughput of a TCP session, I'm getting around 350 Mbps of throughput. When I do the same test with a Cisco switch, I'm getting over 800Mbps of throughput. So I checked the CPU utilization with sar -u 5 100 and top but I don't understand the result. I expected to see a high value for %system, but I'm getting this:

# sar -u 5 100
Linux 3.2.0-4-686-pae (mpcr01) 05/06/14 _i686_ (4 CPU)

07:28:26 PM CPU %user %nice %system %iowait %steal %idle

07:29:26 PM all 0.00 0.00 0.00 0.00 0.00 100.00
07:29:31 PM all 0.00 0.00 0.05 0.00 0.00 99.95
07:29:36 PM all 0.00 0.00 0.37 0.00 0.00 99.63
07:29:41 PM all 0.00 0.00 0.51 0.00 0.00 99.49
07:29:46 PM all 0.00 0.00 0.51 0.00 0.00 99.49

Do I understand correctly that the CPU us utilized at 0.51% only?
How can I improve network performance in bridging?

Thanks,

The primary limiting factor in bridging, at least in my experience, is the performance of the adapter(s) and the system bus width. That's why you find network hardware with the CPU performance of a childs toy handling massive levels of traffic.
I was surprised the first time I noticed that as well, however the more your work with this stuff, the less surprising it becomes to the point where if you see your processor spiking hard on inetd, you know you've mis-configured something.