Messages in this thread | | | Date | Mon, 21 Apr 2008 15:19:38 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH] Re: Bad network performance over 2Gbps |
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Hi!
> [X86] IRQBALANCE: Mark as BROKEN and disable by default > > The IRQBALANCE option causes interrupts to bounce all around on SMP systems > quickly burying the CPU in migration cost and cache misses. Mainly affected are > network interrupts and this results in one CPU pegged in softirqd completely. > > Disable this option and provide documentation to a better solution (userspace > irqbalance daemon does overall the best job to begin with and only manual setting > of smp_affinity will beat it). > > Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com> > > --- > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 6c70fed..956aa22 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1026,13 +1026,17 @@ config EFI > platforms. > > config IRQBALANCE > - def_bool y > + def_bool n
ACK. > prompt "Enable kernel irq balancing" > - depends on X86_32 && SMP && X86_IO_APIC > + depends on X86_32 && SMP && X86_IO_APIC && BROKEN
This is wrong. irqbalance works, there's nothing wrong with it; but it has nasty sideffects.
> help > The default yes will allow the kernel to do irq load balancing. > Saying no will keep the kernel from doing irq load balancing. > > + This option is known to cause performance issues on SMP > + systems. The preferred method is to use the userspace > + 'irqbalance' daemon instead. See http://irqbalance.org/. > +
ACK.
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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