RE: Possible CPU_IDLE bug [WAS: Re: Timer unstability on when usingC2 and deeper sleep states (Dell Latitude XT)]

[Pallipadi, Venkatesh]

>-----Original Message-----
>From: linux-kernel-owner@xxxxxxxxxxxxxxx
>[mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of Milan Plzik
>Sent: Wednesday, August 13, 2008 7:16 AM
>To: linux-kernel@xxxxxxxxxxxxxxx
>Subject: Possible CPU_IDLE bug [WAS: Re: Timer unstability on
>when using C2 and deeper sleep states (Dell Latitude XT)]
>
>  Hello again,
>
>On St, 2008-08-13 at 12:58 +0200, Milan Plzik wrote:
>> I apologize for replying on my own mail (and also for
>top-posting, but
>> this information is global update, not exactly fitting any of topics
>> mentioned below).
>>
>>   After playing for a longer while I found out that the system ends
>> sometimes in state where, in order to do anything useful, I need to
>> press keys on keyboard. Otherwise, the system just stalls and does
>> nothing. I have no idea why does this happen (especially when I know
>> that OHCI or wireless network adapter produce fair amount of
>> interrupts). My /proc/interrupts is below. Just for the record,
>> chipset
>> on board is ATI RS600 with (apparently from lspci) ATI SB600
>> southbridge.
>
>  it looks like this problem disappears if CONFIG_CPU_IDLE option is
>disabled, system seems to be stable for more than one hour. This
>suggests that something may be wrong with the CPU_IDLE code. I can not
>spend much more time by debugging the kernel, but if anyone has an
>suggestion about what to fix, I will gladly test it.
>
>  Best regards,
>        Milan Plzik

It may not be a problem with cpuidle code per se. We have had issues earlier like this one

http://bugzilla.kernel.org/show_bug.cgi?id=10011

Cpuidle tries to go to C3 state aggressively and thus may be indirectly causing the problem with graphics hardware or something like that.

>From Dave's comment in the above bugzilla:
can you try with Option "DRI" "Off" in your xorg.conf

Does that change anything?

Thanks,
Venki
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