e1000 performance issues and broken mtu setting
From: Chris Friesen
Date: Fri Mar 26 2004 - 14:25:32 EST
I've got a pair of dual G5s. For a second gigE link we added in some
Intel 82540EM cards, using the e1000 driver in the 2.6.4 tree with NAPI
enabled. lspci reports the bus as 66MHz. The cards were connected
together with a crossover cable.
A basic UDP packet-blasting program in userspace using 64KB datagrams
could only manage 47MB/s of data throughput, using 20% of a cpu.
For comparison, the same program managed 108.9 MB/s with 30% cpu when
using the onboard gigE ports.
Also, I tried setting a larger mtu using "ip set link dev ethx mtu
xxxxx". No matter what value I chose (even setting it to its default
value, which should have had zero effect) it resulted in the link not
being able to transfer data. Downing/upping the link didn't clear the
issue, neither did unloading/reloading the driver module. It took a
reboot to actually get it working again.
Any ideas what's going on?
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