[CentOS] Intel 82579V ethernet nic using only one IRQ? (Dual TX RX queues)

Sun Jun 9 05:44:53 UTC 2013
John R Pierce <pierce at hogranch.com>

On 6/8/2013 9:46 PM, Alex Flex wrote:
> So I bought a NIC (using the  Intel 82579V chipset) that supports Dual
> RX and TX queues , my goal with that is so iam able to see and use two
> IRQs in /proc/interrupts and hence be able to take advantage of 2 cores
> on my CPU. Instead I only see one IRQ being used, and hence only one CPU
> core.. Please see below.
> Advisement is appreciated!

wait, the 82579 is just a PHY layer for the Intel 6 Series Express CPU 
chipset's built in MAC (p67, z68, hm67, etc chipsets for the Sandy 
Bridge family of desktop/mobile CPUs).   That combination is also a 
'entry level' desktop/workstation or 'mobile embedded' grade ethernet 
interface, not really a server grade interface at all.

regardless, its a single device.   single devices, regardless of how 
many queues they may happen to have, are not reentrant, and can not deal 
with multiple concurrent IRQ handlers poking at their registers at the 
same time.

you might have more luck with something like this
but even so, I doubt it will use multiple CPU cores at the same time, 
but it probably WILL significantly reduce the CPU overhead of dealing 
with high volume ethernet traffic.

john r pierce                                      37N 122W
somewhere on the middle of the left coast