Re: [Xen-devel] Only CPU0 active after ACPI S3, xen 4.1.3

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 16/01/13 13:08, Jan Beulich wrote:
> > > > On 16.01.13 at 12:58, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> > On 16/01/13 11:22, George Dunlap wrote:
> > > Jan, the commit message isn't very informative -- can you point me to
> Which commit message?
>
> > > a conversation describing the problem you're fixing wrt
> > > suspend/resume, and/or describe what you were trying to do?  Given the
> > > results, the whole thing about not disabling scheduling during suspend
> > > seems a bit suspect...
> > In particular, just on a fairly cursory bit of function call skimming,
> > it looks like:
> > * This change means that cpupool.c:cpu_callback() won't call
> > cpupool_cpu_add() when resuming
> > * cpupool_cpu_add() does a bunch of paperwork (which would be
> > unnecessary given the changes re suspend), but also calls
> > cpupool_assign_cpu_locked()
> > * cpupool_assign_cpu_locked() calls schedule_cpu_switch()
> > * schedule_cpu_switch() calls the scheduler's tick_resume()
> >
> > So is it possible that on resume ticks are not being re-enabled, or
> > something like that?
> I don't see a problem here - it's symmetric (nothing done on
> suspend, and nothing done on resume).
Well it would be if it was only data, but it's not.  That's my point.  
Before this changeset (xen-unstable 25079:d5ccb2d1dbd1), ticks were 
suspended and resumed on the CPU (i.e., timer interrupts turned off and 
on), and after the patch, they're not.  Doesn't suspend disable / muck 
with timer interrupts?
 -George

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