Re: Only CPU0 active after ACPI S3, xen 4.1.3

[George Dunlap <george.dunlap@eu.citrix.com>]

On 16/01/13 13:08, Jan Beulich wrote:
>>>> On 16.01.13 at 12:58, George Dunlap <george.dunlap@eu.citrix.com> 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