NUMA local PCI-Express interfaces

With Sandybridge PCI-Express slots are now local to a particular socket and therefore NUMA node.

If you're connecting to a specific NIC then it makes sense to make sure you're on the same NUMA node as the NIC is, thereby preventing having to shuttle data over the QPI between the kernel buffers and your user-space buffers.

Details on what NUMA nodes a particular NIC is on can be found as follows:

/sys/class/net/eth0/device $ cat numa_node
0

/sys/class/net/eth0/device $ cat local_cpus
00005555

/sys/class/net/eth0/device $ cat local_cpulist
0,2,4,6,8,10,12,14