Messages in this thread | | | Subject | Re: [2.6.36.1] IGB driver handles all ethX interrupts on single cpu core. | From | Eric Dumazet <> | Date | Wed, 08 Dec 2010 08:59:25 +0100 |
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Le mercredi 08 décembre 2010 à 08:45 +0100, Paweł Sikora a écrit : > On Wednesday 08 of December 2010 02:44:25 Robert Hancock wrote: > > On 12/07/2010 12:06 PM, Paweł Sikora wrote: > > > hi, > > > > > > i'm currently testing a new server with 2x opteron-6128 with dual gigabit port > > > and observing that the igb driver uses only single core for all ethX interrupts. > > > is it a correct behaviour for this driver? > > > > > > BR, > > > Pawel. > > > > The CPU affinity for the IRQ isn't really under the driver's control. It > > looks like all your interrupts are being handled on CPU0. You likely > > need to run the irqbalance daemon. > > ok, so why e.g. on one machine (dual amd opteron) irqbalance daemon is required > and on second machine (single intel quad-core) irqs are balanced w/o daemon? > this looks inconsistent to me. > > $ cat /proc/interrupts > CPU0 CPU1 CPU2 CPU3 > 0: 49 2 0 0 IO-APIC-edge timer > 1: 0 1 0 1 IO-APIC-edge i8042 > 8: 13 11 12 13 IO-APIC-edge rtc0 > 9: 0 0 0 0 IO-APIC-fasteoi acpi > 12: 0 0 3 1 IO-APIC-edge i8042 > 16: 224 236 235 232 IO-APIC-fasteoi pata_marvell, uhci_hcd:usb3 > 17: 0 0 0 0 IO-APIC-fasteoi saa7133[0], saa7133[0] > 18: 0 0 0 0 IO-APIC-fasteoi ehci_hcd:usb1, uhci_hcd:usb5, uhci_hcd:usb8 > 19: 695 672 660 630 IO-APIC-fasteoi uhci_hcd:usb7 > 21: 0 0 0 0 IO-APIC-fasteoi uhci_hcd:usb4 > 23: 1 1 1 0 IO-APIC-fasteoi ehci_hcd:usb2, uhci_hcd:usb6 > 40: 3409 3446 3441 3403 PCI-MSI-edge ahci > 41: 63 60 60 61 PCI-MSI-edge hda_intel > 42: 3219 3180 3237 3192 PCI-MSI-edge radeon > 43: 505 487 496 498 PCI-MSI-edge eth0
irqbalance is not required.
You can decide yourself of IRQ affinities
Given data you provided :
echo 0f >/proc/irq/*/eth0/../smp_affinity
If your IGB card has 4 queues and you want each queue serviced by a given cpu :
echo 01 >/proc/irq/*/eth0-fp-0/../smp_affinity echo 02 >/proc/irq/*/eth0-fp-1/../smp_affinity echo 04 >/proc/irq/*/eth0-fp-2/../smp_affinity echo 08 >/proc/irq/*/eth0-fp-3/../smp_affinity
Note 1 : If under load, NAPI is triggered and no anymore hardirqs are delivered, so load stay on one ksoftirqd (one cpu), no matter changes you make on /proc/irq/...
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