lkml.org 
[lkml]   [2010]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [2.6.36.1] IGB driver handles all ethX interrupts on single cpu core.
From
Date
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/...



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2010-12-08 09:01    [W:0.047 / U:1.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site