Bruce Allen wrote: > Details: > Kernel version: 2.6.23.12 > ethernet NIC: Intel 82573L > ethernet driver: e1000 version 7.3.20-k2 > motherboard: Supermicro PDSML-LN2+ (one quad core Intel Xeon X3220, > Intel 3000 chipset, 8GB memory)
Hi Bruce, The 82573L (a client NIC, regardless of the class of machine it is in) only has a x1 connection which does introduce some latency since the slot is only capable of about 2Gb/s data total, which includes overhead of descriptors and other transactions. As you approach the maximum of the slot it gets more and more difficult to get wire speed in a bidirectional test. > The test was done with various mtu sizes ranging from 1500 to 9000, > with ethernet flow control switched on and off, and using reno and > cubic as a TCP congestion control. As asked in LKML thread, please post the exact netperf command used to start the client/server, whether or not you're using irqbalanced (aka irqbalance) and what cat /proc/interrupts looks like (you ARE using MSI, right?) I've recently discovered that particularly with the most recent kernels if you specify any socket options (-- -SX -sY) to netperf it does worse than if it just lets the kernel auto-tune. > The behavior depends on the setup. In one test we used cubic > congestion control, flow control off. The transfer rate in one > direction was above 0.9Gb/s while in the other direction it was 0.6 > to 0.8 Gb/s. After 15-20s the rates flipped. Perhaps the two steams > are fighting for resources. (The performance of a full duplex stream > should be close to 1Gb/s in both directions.) A graph of the > transfer speed as a function of time is here: > https://n0.aei.uni-hannover.de/networktest/node19-new20-noflow.jpg > Red shows transmit and green shows receive (please ignore other > plots): One other thing you can try with e1000 is disabling the dynamic interrupt moderation by loading the driver with InterruptThrottleRate=8000,8000,... (the number of commas depends on your number of ports) which might help in your particular benchmark. just for completeness can you post the dump of ethtool -e eth0 and lspci -vvv? Thanks, Jesse -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
