Re: nmi_watchdog fix for x86_64 to be more like i386

[Arjan van de Ven <arjan@infradead.org>]

On Tue, 2 Oct 2007 00:47:12 +0200 (CEST)
Thomas Gleixner <tglx@linutronix.de> wrote:

> On Tue, 2 Oct 2007, Andi Kleen wrote:
> > 
> > > OTOH, the accounting hook would allow us to remove the IRQ#0 ->
> > > CPU#0 restriction. Not sure whether it's worth the trouble.
> > 
> > Some SIS chipsets hang the machine when you migrate irq 0 to another
> > CPU. It's better to keep that Also I wouldn't be surprised if there
> > are some other assumptions about this elsewhere.
> > 
> > Ok in theory it could be done only on SIS, but that probably would
> > really not be worth the trouble
> 
> Agreed.
> 
> I just got a x8664-hrt report, where I found the following oddity:
> 
>  0:       1197     172881   IO-APIC-edge      timer
> 
> That's one of those infamous AMD C1E boxen. Strange, all my systems
> have IRQ#0 on CPU#0 and nowhere else. Any idea ?

2 things;
the current irq balancers don't balance the timer interrupt, in fact
they'll leave it alone (so the chipset might balance)
older ones pin it to cpu 0 or rotate it....