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Subject: RE: Possible CPU_IDLE bug [WAS: Re: Timer unstability on when
	using C2 and deeper sleep states (Dell Latitude XT)]
From: Milan Plzik <milan.plzik@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Date: Thu, 14 Aug 2008 15:28:27 +0200
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On Št, 2008-08-14 at 13:40 +0200, Milan Plzik wrote:
> On Št, 2008-08-14 at 11:00 +0200, Thomas Gleixner wrote:
> > On Thu, 14 Aug 2008, Milan Plzik wrote:
> > >   I tried it just now, is performs a bit better than 2.6.26 (e.g. I
> > > don't get that "press any key unless nothing happens" states), even
> > > reports a bit more reasonable values of wakeups, but the system
> > > sometimes becomes rather slow (e.g. when playing video). I was not able
> > > to compile fglrx driver, so I had to change it to radeon one. And also,
> > > the number of wakeups reported is not very convincing, though, it
> > > changes from 300 to 600 (which is ~ two times the sum of wakeups)
> > > without any reason, and sometimes goes even higher.
> > > 
> > >   I tried to use nolapic_timer option, but it didn't help.
> > 
> > Can you please try "hpet=disable" on the kernel command line ?
> 
>   Looks like this has helped; after cold reboot hpet=disable seems to
> help the system to run properly (on 2.6.26 kernel). I wonder what could
> cause these problems. In the meanwhile I learned that this machine
> doesn't do proper cleanup during reboot -- it seems that state before
> reboot affects the state after reboot, so I should probably do some
> re-testing with cold reboot after each attempt. I guess I tried
> hpet=disable some time ago and after quick reboot it did not work
> properly.

  UPDATE: looks like it doesn't help always. I cold-booted twice, once
hpet=disable didn't help and the timing was messed up, the other time it
seemed to work just correctly. Maybe it's some race condition during
startup, but I was not able to find any substantial difference in kernel
messages emitted during boot, (just little changes like 2401.86 BogoMIPS
processor vs. 2401.88 and similar). 

> 
> > 
> > Thanks,
> > 	tglx
> 
>   Thank you,
> 	Milan

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