Date: Tue, 11 Jan 2005 21:18:10 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Mikael Pettersson <mikpe@csd.uu.se>
Cc: Pavel Machek <pavel@ucw.cz>, Bernard Blackham <bernard@blackham.com.au>,
       Shaw <shawv@comcast.net>, linux-kernel@vger.kernel.org
Subject: Re: Screwy clock after apm suspend
Message-ID: <20050111201810.GA1464@openzaurus.ucw.cz>
References: <20050109224711.GF1353@elf.ucw.cz> <200501092328.54092.shawv@comcast.net> <20050110074422.GA17710@mussel> <20050110105759.GM1353@elf.ucw.cz> <20050110174804.GC4641@blackham.com.au> <20050111001426.GF1444@elf.ucw.cz> <20050111011611.GE4641@blackham.com.au> <16867.51258.916944.195917@alkaid.it.uu.se> <20050111131019.GA1324@openzaurus.ucw.cz> <16867.57217.358323.945559@alkaid.it.uu.se>
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Hi!

>  > >  > Looking harder, in arch/i386/kernel/apm.c the system time is also
>  > >  > saved and restored in a very similar way to timer_suspend/resume.
>  > >  > Would this account for the time drift in APM mode? (sleep time being
>  > >  > accounted for twice?)
>  > > 
>  > > No, apm.c's update to xtime is absolute, just like time.c's.
>  > > Doing both is pointless but not harmful. (I've already tried
>  > > with apm.c's xtime update commented out, but the time-warp
>  > > bug remained.)
>  > > 
>  > > My 0.02 SEK says it's the jiffies update that's broken.
>  > 
>  > Okay, can you
>  > 
>  > * kill jiffie update (x86-64, too)
>  > * remove apm.c variant
>  > * test it (or make someone test it) with apm?
>  > 
>  > I now see the drift with acpi, too :-(. I can do the acpi testing...
> 
> I'm away from my APM laptop until Friday, but I'll do this test then.

Now I recall why jiffies need to be updated: if they are not, ps
shows wrong process start times after resume.

If it causes worse problems, we may temporarily back that out, but...
				Pavel
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