From: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
       Andi Kleen <andi@firstfloor.org>
CC: Mark Hounschell <markh@compro.net>,
       "dmarkh@cfl.rr.com" <dmarkh@cfl.rr.com>, Alain Knaff <alain@knaff.lu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       "fdutils@fdutils.linux.lu" <fdutils@fdutils.linux.lu>,
       "Li, Shaohua" <shaohua.li@intel.com>, Ingo Molnar <mingo@elte.hu>
Date: Wed, 23 Dec 2009 09:19:42 -0800
Subject: RE: [Fdutils] DMA cache consistency bug introduced in 2.6.28
Thread-Topic: [Fdutils] DMA cache consistency bug introduced in 2.6.28
Thread-Index: AcqD8B6dcCBJAY4DSd+tPU5Tp2giogAA4NWQ
Message-ID: <6598A4E21F1DB24D80BF72956484F59802EFD2F1@orsmsx001.amr.corp.intel.com>
References: <4AFB3962.2020106@ntlworld.com> <4B2B4485.6000305@cfl.rr.com>
 <4B2B5F86.1090403@cfl.rr.com>
 <alpine.LFD.2.00.0912180716400.3712@localhost.localdomain>
 <4B2B9F9F.7040802@compro.net>
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 <4B2BE05B.9050006@compro.net>
 <alpine.LFD.2.00.0912181213540.3712@localhost.localdomain>
 <4B30E1B4.7000702@compro.net>
 <alpine.LFD.2.00.0912220922250.31313@localhost.localdomain>
 <4B310879.9050701@compro.net> <1261525076.16916.4.camel@localhost.localdo
 main> <4B3162BC.9000508@cfl.rr.com> <4B3214EC.6020308@compro.net>
 <6598A4E21F1DB24D80BF72956484F59802EFD1C6@orsmsx001.amr.corp.intel.com>
 <4B32386B.2060509@compro.net>
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>-----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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