linux-kernel - Re: [Fdutils] DMA cache consistency bug introduced in 2.6.28

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Message-ID: <4B32565E.6000501@compro.net>
Date:	Wed, 23 Dec 2009 12:41:50 -0500
From:	Mark Hounschell <markh@...pro.net>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	"dmarkh@....rr.com" <dmarkh@....rr.com>,
	Alain Knaff <alain@...ff.lu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"fdutils@...tils.linux.lu" <fdutils@...tils.linux.lu>,
	"Li, Shaohua" <shaohua.li@...el.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [Fdutils] DMA cache consistency bug introduced in 2.6.28

On 12/23/2009 11:38 AM, Andi Kleen wrote:
> Linus Torvalds <torvalds@...ux-foundation.org> writes:
> 
>> It's not using the lapic for CPU0. 
>>
>> Using the HPET as a per-cpu timer is some crazy sh*t, since it's pretty 
>> expensive to reprogram (compared to the local apic). And having different 
>> timers for different CPU's is just odd.
>>
>> The fact that the timer subsystem can do this and it all (mostly) works at 
>> all is nice and impressive, but doesn't make it any less crazy ;)
> 
> 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.
> 
> This might suggest that Mark's floppy controller doesn't like
> deep C? Mark, did you try booting with processor.max_cstate=1
> and HPET enabled?

I just did and /proc/interrupts looks the same and the floppy still does
not format.

I'll try the patch Linus provided now.

Mark

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