[Requested by Matti Aarnio on the centos mailing list on Aug 11, 2011]<br />
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Hi,<br />
<br />
Could CentOS kernel keepers apply following patch on current kernel?<br />
<a href="http://patchwork.ozlabs.org/patch/95785/">http://patchwork.ozlabs.org/patch/95785/</a> [<a href="http://patchwork.ozlabs.org/patch/95785/" target="_blank">^</a>]<br />
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(Current as: 2.6.32-71.29.1.el6.x86_64)<br />
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With the patch applied, and a ".local" kernel built, I get 30% higher throughput with vmxnet3 in my IP routing node, than when using e1000 "card" at the same. Without the patch, the TCP flow over vmxnet3 driver on a _router_ node is abysmally slow.<br />
<br />
I am running a bunch of CentOS servers on VMware ESXi 4.1U1 hosts with multiple of VLANs.<br />
The best network performance is obtainable with vmxnet3 network driver in normal case.<br />
This driver includes so called LRO optimization, which boosts TCP flow network performance on end-nodes, but kills it on routers, thus the LRO mode needs to be disabled on a host doing routing in between network interfaces.<br />
<br />
The issue is a bug in vmxnet3 driver, which is not able to disable LRO mode when the kernel is telling the driver to do so.<br />
The patch for it applies on 2.6.32 kernels as well as 2.6.38/39 where it got applied to baseline.<br />
<br />
Could this be applied on stock CentOS kernel so that I could return on un-customized kernel use?<br />
<br />
Best Regards, Matti Aarnio
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