Hello! We just got a nice file server with an Intel 82599EB 10GB Ethernet adapter, and are trying various things for optimal performance.
That tcp-segmentation-offload is working really great, and I can see 64k packets going in and 1518 byte packets coming out on the wire in amazing speed, we can easily saturate the 1GBit the blade client is connected with with 938 MBit/s. Now, I thought, increasing the interface MTU to 9000 should boost performance even more, but instead it reduced it to about 600MBit/s, apparently because the tcp offloading is not working as before. The maximum frame size I see going to the interface is 17962 Bytes, and also quite a few with 9018 bytes. Any hint what might be the cause for that, or what I have missed? One guess is that the asymmetrical setup here (sending on 10GBE, receiving on 1GB) might cause it, but looking at the packet dumps it should work like a charm, no lost packets, of course with "TCP Window full" all the time. The receiver uses a Broadcom Corporation NetXtreme II BCM5708S 1GBit adapter, is this one maybe known to have problems with large MTUs? After all that "MTU 9000 considered harmful" statements, is there a more useful large PDU? I also tried 8252, but it still achieves very bad performance with the largest tcp segment beeing 16478 bytes. Operating system is openSuse 12.1, "modinfo ixgbe" shows driver version "3.4.8-k" Ring buffers are available, as far as I can tell: # ethtool -k eth4 Offload parameters for eth4: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp-segmentation-offload: on udp-fragmentation-offload: off generic-segmentation-offload: on generic-receive-offload: on large-receive-offload: on rx-vlan-offload: on tx-vlan-offload: on ntuple-filters: off receive-hashing: on # ethtool -g eth4 Ring parameters for eth4: Pre-set maximums: RX: 4096 RX Mini: 0 RX Jumbo: 0 TX: 4096 Current hardware settings: RX: 512 RX Mini: 0 RX Jumbo: 0 TX: 512 Thanks for any help or pointers. Regards, Walter -- Walter Zimmer German Aerospace Center (DLR) Earth Observation Center (EOC) Remote Sensing Technology Institute (IMF) Department Atmospheric Processors (AP) Oberpfaffenhofen 82234 Wessling Tel.: +49 (8153) 28 1492 Fax: +49 (8153) 28 1446 email: [email protected] Internet: http://www.dlr.de/eoc ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
