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

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Message-ID: <4B3270FE.5090607@compro.net>
Date:	Wed, 23 Dec 2009 14:35:26 -0500
From:	Mark Hounschell <markh@...pro.net>
To:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
CC:	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"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 02:18 PM, Pallipadi, Venkatesh wrote:
> On Wed, Dec 23, 2009 at 09:41:50AM -0800, Mark Hounschell wrote:
>> 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.
>>
> 
> Can you try this one line patch either on .28 or .32 (with /proc/interrupts
> output).
> This disables hpet2 and lapic timer should then be used on CPU 0. If things
> work with this test patch, we will know that the failure is somehow related
> to HPET usage in MSI mode.
> 
> Thanks,
> Venki
> 
> Reduce the rating of percpu hpet timer
> 
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
> ---
>  arch/x86/kernel/hpet.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
> index cafb1c6..f89d17a 100644
> --- a/arch/x86/kernel/hpet.c
> +++ b/arch/x86/kernel/hpet.c
> @@ -480,7 +480,7 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
>  	hpet_setup_irq(hdev);
>  	evt->irq = hdev->irq;
>  
> -	evt->rating = 110;
> +	evt->rating = 40;
>  	evt->features = CLOCK_EVT_FEAT_ONESHOT;
>  	if (hdev->flags & HPET_DEV_PERI_CAP)
>  		evt->features |= CLOCK_EVT_FEAT_PERIODIC;

That made it work. Used 2.6.32.2

cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3
  0:         82          0          0          1   IO-APIC-edge      timer
  1:          0          0          0         67   IO-APIC-edge      i8042
  3:          0          0          0          6   IO-APIC-edge
  4:          0          0          0          4   IO-APIC-edge
  6:          0          0          0          4   IO-APIC-edge      floppy
  8:          0          0          0          8   IO-APIC-edge      rtc0
  9:          0          0          0          0   IO-APIC-fasteoi   acpi
 12:          0          0         10       1519   IO-APIC-edge      i8042
 14:          0          0         39      10995   IO-APIC-edge
pata_atiixp
 15:          0          0          3        391   IO-APIC-edge
pata_atiixp
 16:          0          0          2        606   IO-APIC-fasteoi
aic79xx, ohci_hcd:usb3, ohci_hcd:usb4, HDA Intel, Digi DBX2, ni-pci-gpib
 17:          0          0          0          3   IO-APIC-fasteoi
ehci_hcd:usb1, parport0, ni-pci-gpib
 18:          0          0         10       2168   IO-APIC-fasteoi
ohci_hcd:usb5, ohci_hcd:usb6, ohci_hcd:usb7, Digi DBX2, nvidia
 19:          0          0          0        130   IO-APIC-fasteoi
aic7xxx, ehci_hcd:usb2, ttySLG0, eth1
 22:          0          0          8       1151   IO-APIC-fasteoi   ahci
 24:          0          0          0          0  HPET_MSI-edge      hpet2
 29:          0          0          0         48   PCI-MSI-edge
sky2@pci:0000:04:00.0
NMI:          0          0          0          0   Non-maskable interrupts
LOC:      34842      30177      29672      29632   Local timer interrupts
SPU:          0          0          0          0   Spurious interrupts
PMI:          0          0          0          0   Performance monitoring
interrupts
PND:          0          0          0          0   Performance pending work
RES:      17501      20449      16670      11224   Rescheduling interrupts
CAL:      10554       2336       1102       1071   Function call interrupts
TLB:        364        562        753        468   TLB shootdowns
ERR:          0
MIS:          0


# fdformat /dev/fd0u1440
Double-sided, 80 tracks, 18 sec/track. Total capacity 1440 kB.
Formatting ... done
Verifying ... done
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