From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Friesen Subject: strange e1000 performance issues Date: Fri, 09 Apr 2004 03:23:53 -0400 Sender: netdev-bounce@oss.sgi.com Message-ID: <40764F89.8090306@nortelnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: netdev@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org I've got a pair of dual G5s running 2.6.4. For a second gigE link we added in some Intel 82540EM cards, using the mainline e1000 driver 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? Thanks, Chris