Alex Flex
2013-Jun-09 04:46 UTC
[CentOS] Intel 82579V ethernet nic using only one IRQ? (Dual TX RX queues)
Hello CentOS Community,
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!
Alex
--------------------------------------------------------------------------------------------------------------------------------
LAN support Gigabit (10/100/1000 Mbits/sec) LAN subsystem using the
Intel? 82579V Gigabit Ethernet Controller
http://www.intel.com/content/www/us/en/motherboards/desktop-motherboards/desktop-board-dh77eb.html
[root at nodeA LabTests]# cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3
{...}
33: 180364 0 0 0 IR-PCI-MSI-edge eth0
DMESG:
e1000e 0000:00:19.0: eth0: (PCI Express:2.5GT/s:Width x1) 00:22:4d:9d:55:13
e1000e 0000:00:19.0: eth0: Intel(R) PRO/1000 Network Connection
e1000e 0000:00:19.0: eth0: MAC: 10, PHY: 11, PBA No: FFFFFF-0FF
e1000e 0000:00:19.0: irq 33 for MSI/MSI-X
e1000e 0000:00:19.0: irq 33 for MSI/MSI-X
ADDRCONF(NETDEV_UP): eth0: link is not ready
e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: Rx/Tx
e1000e 0000:00:19.0: eth0: 10/100 speed: disabling TSO
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
eth0: no IPv6 routers present
usb 1-1.5: USB disconnect, device number 3
lo: Disabled Privacy Extensions
e1000e 0000:00:19.0: irq 33 for MSI/MSI-X
e1000e 0000:00:19.0: irq 33 for MSI/MSI-X
ADDRCONF(NETDEV_UP): eth0: link is not ready
e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: Rx/Tx
e1000e 0000:00:19.0: eth0: 10/100 speed: disabling TSO
ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
eth0: no IPv6 routers present
Intel? 82579V
John R Pierce
2013-Jun-09 05:44 UTC
[CentOS] Intel 82579V ethernet nic using only one IRQ? (Dual TX RX queues)
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 http://ark.intel.com/products/59062/Intel-Ethernet-Server-Adapter-I350-T2 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
Tilman Schmidt
2013-Jun-09 17:06 UTC
[CentOS] Intel 82579V ethernet nic using only one IRQ? (Dual TX RX queues)
Am 09.06.2013 06:46, schrieb Alex Flex:> Hello CentOS Community, > > 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.First, yes, the NIC will only use one IRQ. That is as it should be. Second, no, that doesn't mean that only one CPU core will be used. Very little work is done inside the ISR, because that work must be strictly serialized. The bulk of the work is done outside interrupt context, and that work is distributed over the CPU cores by the scheduler. Distributing the IRQs would unnecessarily complicate things without buying you any performance improvement. HTH T. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 261 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20130609/73a45528/attachment-0005.sig>