RE: nmi_watchdog fix for x86_64 to be more like i386

["Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>]

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org 
>[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of 
>Thomas Gleixner
>Sent: Monday, October 01, 2007 11:19 PM
>To: Andi Kleen
>Cc: Arjan van de Ven; David Bahi; LKML; 
>linux-rt-users@vger.kernel.org; Andrew Morton; Ingo Molnar; 
>Gregory Haskins
>Subject: Re: nmi_watchdog fix for x86_64 to be more like i386
>
>>
>> The only workaround for chipsets ignoring IRQ affinity would 
>be to keep
>> track on which CPU irq 0 happens and then restart APIC timer 
>interrupts
>> on the others (or send IPIs) as needed. But that would be 
>fairly ugly.
>
>The clock events code does handle this already. The broadcast 
>interrupt 
>can come in on any cpu. It's just the nmi watchdog which would 
>be affected 
>by that.
>

Probably we can workaround this by keeping track of IRQ0 count at percpu
level and
use local apic timer + this percpu counter in NMI. Or just increment
local
apic timer count in IRQ0 with nohz enabled.

Thanks,
Venki
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