linux-kernel - Re: Timer unstability on when using C2 and deeper sleep states (Dell Latitude XT)

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Message-Id: <1218637994.5250.22.camel@localhost>
Date:	Wed, 13 Aug 2008 16:33:14 +0200
From:	Milan Plzik <milan.plzik@...il.com>
To:	Pavel Machek <pavel@...e.cz>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Timer unstability on when using C2 and deeper sleep states
	(Dell Latitude XT)

On St, 2008-08-13 at 15:05 +0200, Pavel Machek wrote:
> Hi!

  Hello,

  I apologize, I have not seen your reply, the newest update already
describes my situation.

> 
> >   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
> 
> I have seen it before with NOHZ problems. Try nohz=off, highres=off ?
> 

  I tried nohz=off; result was stably working system, but the cause
could be that it virtually did not enter any of deeper C states (I also
had HZ configured to 1000, but I'm not sure whether that matters when
calculating efficieny of switching to Cx state). I also tried to disable
hpet at all, and to disable support for high resolution timers in
kernel, but result was the same, IIRC. Unless I wasn't entering C2 or
C3, the system was stable.

	Milan

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