Re: [Qemu-devel] ballooning not working on hotplugged pc-dimm

[zhanghailiang]

On 2014/9/9 11:05, Alexandre DERUMIER wrote:
> Hello,
>
> I was playing with pc-dimm hotplug, and I notice that balloning is not working 
> on
> memory space of pc-dimm devices.
>
> example:
>
> qemu -m size=1024,slots=255,maxmem=15000M
>
> #free -m : 1024M
> ->  qmp balloon 512M
> #free -m : 512M
>
> ->  hotplug pc-dimm 1G:
>
> #free -m : 1512M
>
>
> (This is the same behavior if qemu is started with pc-dimm devices)
>
>
> qemu 2.1
> Guest kernel : 3.12.
>
>
>
> Does it need a guest balloon module update ?
>
> Regards,
>
> Alexandre Derumier
Hi,

I noticed this fault also;-), this is a bug in qemu, And some work in process...

Actually in QEMU the hotplugged memory(named hotplug-memory) is distinguished
from the common memory(named pc.ram). When do balloon action, QEMU wrongly
stats the ram_size.

I will send a patch series which also include other bug fix for the memory 
hotplug.

Thanks,
zhanghailiang