Re: irqbalance mandatory on SMP kernels?
From: Arjan van de Ven
Date: Mon Apr 17 2006 - 09:10:33 EST
> [jackson:stock]:(/usr/src/linux)$ cat /proc/interrupts
> CPU0 CPU1
> 0: 3139568 0 IO-APIC-edge timer
> 1: 8923 0 IO-APIC-edge i8042
> 3: 10 0 IO-APIC-edge serial
> 4: 37 0 IO-APIC-edge serial
> 8: 0 0 IO-APIC-edge rtc
> 9: 240 0 IO-APIC-level acpi
> 12: 75316 0 IO-APIC-edge i8042
> 14: 64291 0 IO-APIC-edge ide0
> 15: 64291 0 IO-APIC-edge ide1
> 16: 235408 0 IO-APIC-level HiSax, nvidia
> 17: 15823 0 IO-APIC-level libata, AMD AMD8111
> 19: 241 0 IO-APIC-level ohci_hcd, ohci_hcd, ohci1394
> 24: 50761 0 IO-APIC-level eth0
> NMI: 89 28
> LOC: 3139042 3139125
> ERR: 0
> MIS: 0
> [jackson:stock]:(/usr/src/linux)$
this may or may not be a problem depending on how long a time you used
to collect this. Based on your timer tick count it really looks like
your irq rates are so low that it really doesn't matter much
>
> Only when firing up the irqbalance util at boot time will activate
> true SMP, distributing IRQ's across CPU's. Is this on purpose?
> Because afaik a Linux SMP kernel, 2.4.xx or 2.6.xx should always
> result in distributed IRQ loads across CPU's.
that is a chipset feature if it happens; not all chipsets do this (and
most that do, do it badly).
I'm not sure what your actual problem is btw, the irqbalance tool is
supposed to automatically start at boot, did it not do that ?
(and no the kernel doesn't need to do everything, something like this
can perfectly well be done in userspace as irqbalance shows)
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