Re: peculiar suspend/resume bug.

From: Dave Jones
Date: Tue Aug 15 2006 - 20:35:18 EST

On Wed, Aug 16, 2006 at 10:19:59AM +1000, Nigel Cunningham wrote:
> Hi Dave.
> On Tue, 2006-08-15 at 18:10 -0400, Dave Jones wrote:
> > Here's a fun one.
> > - Get a dual core cpufreq aware laptop (Like say, a core-duo)
> > - Add a cpufreq monitor to gnome-panel. Configure it
> > to watch the 2nd core.
> > - Suspend.
> > - Resume.
> >
> > Watch the cpufreq monitor die horribly.
> >
> > I believe this is because we take down the 2nd core at suspend
> > time with cpu hotplug, and for some reason we're scheduling
> > userspace before we bring that second core back up.
> >
> > Anyone have any clues why this is happening?
> If you hotunplug and replug the cpu using the sysfs interface, rather
> than suspending and resuming, does the same thing happen?

cpufreq-applet crashes as soon as the cpu goes offline.
Now, the applet should be written to deal with this scenario more
gracefully, but I'm questioning whether or not userspace should
*see* the unplug/replug that suspend does at all.

IMO, when we shouldn't schedule userspace until the system is
in the exact state it was before we suspended.


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