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SubjectRE: [Fdutils] DMA cache consistency bug introduced in 2.6.28


>-----Original Message-----
>From: Linus Torvalds [mailto:torvalds@linux-foundation.org]
>Sent: Wednesday, December 23, 2009 8:50 AM
>To: Andi Kleen
>Cc: Mark Hounschell; Pallipadi, Venkatesh; dmarkh@cfl.rr.com;
>Alain Knaff; Linux Kernel Mailing List;
>fdutils@fdutils.linux.lu; Li, Shaohua; Ingo Molnar
>Subject: Re: [Fdutils] DMA cache consistency bug introduced in 2.6.28
>
>
>
>On Wed, 23 Dec 2009, Andi Kleen wrote:
>>
>> I suspect it's a system where the APIC timer stops in deeper idle
>> states and it supports them. In this case CPU #0 does timer
>broadcasts
>> when needed to wake the other CPUs up from deep C, but for
>that it has
>> to run with HPET. At least the other ones can still enjoy the LAPIC
>> timer.
>
>Ahh, ok, that makes sense. I was assuming the broadcast timer
>would act in
>that capacity, but..

This is what I was thining yday and asked Mark to try idle=halt.
This /proc/interrupts is with idle=halt when there should not be any
C-states and broadcasts involved.
>>> HPET_MSI-edge hpet2
>>> NMI: 0 0 0 0
>>> Non-maskable interrupts
>>> LOC: 268 513395 513138 522088 Local timer
>>> interrupts

Not sure how this is related to floppy problem. But, we surely
have something wrong with percpu HPET usage here.

Thanks,
Venki


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