Re: cpuset trouble after hibernate

[Balbir Singh <balbir@linux.vnet.ibm.com>]

Andrew Morton wrote:
> On Mon, 10 Sep 2007 11:45:10 +0200 (CEST) Simon Derr <Simon.Derr@bull.net> wrote:
> 
>> On Sat, 8 Sep 2007, Nicolas Capit wrote:
>>
>>> Hello,
>>>
>>> This is my situation:
>>>   - I mounted the pseudo cpuset filesystem into /dev/cpuset
>>>   - I created a cpuset named oar with my 2 cpus
>>>
>>> cat /dev/cpuset/oar/cpus 
>>> 0-1
>>>
>>>   - Then I hibernate my computer with 'echo -n "disk" >/sys/power/state'
>>>   - After reboot:
>>>
>>> cat /dev/cpuset/oar/cpus 
>>> 0
>>>
>>> Why did I lost a cpu?
>>> Is this a normal behavior???
>> Hi Nicolas,
>>
>> I believe this is related to the fact that hibernation uses the hotplug 
>> subsystem to disable all CPUs except the boot CPU.
>>
>> Thus guarantee_online_cpus() is called on each cpuset and removes all 
>> CPUs, except CPU 0, from all cpusets.
>>
>> I'm not quite sure about if/how this should be fixed in the kernel, 
>> though. Looks like a very simple user-land workaround would be enough.
>>
> 
> Yeah.  Bug, surely.  But I guess it's always been there.
> 
> What are the implications of this for cpusets-via-containers?
> 

I suspect the functionality of cpusets is not affected by containers.

I wonder if containers should become suspend/resume aware and pass
that option on to controllers. I think it's only the bus drivers
and device drivers that do that now.



-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL