Re: cpuset trouble after hibernate

From: Simon Derr
Date: Mon Sep 10 2007 - 05:45:40 EST


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.

Simon.

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