Re: [Qemu-devel] incorrect memory size inside vm

[Andrey Korolyov]

On Mon, Jun 22, 2015 at 4:30 PM, Piotr Rybicki
<address@hidden> wrote:
>
>
> W dniu 2015-06-19 o 14:01, Andrey Korolyov pisze:
>
>> On Fri, Jun 19, 2015 at 2:14 PM, Piotr Rybicki
>> <address@hidden> wrote:
>>>
>>> Hello.
>>>
>>> Actually it was my mistake.
>>> After some time using memory in guest (find /, cp bigfine, etc), res size
>>> of
>>> qemu process shrinks to expected value.
>>>
>>> Sorry for disturbing.
>>> Now i don't see any memory waste in guest and host when using 'base'
>>> memory
>>> + 'dimm' memory.
>>>
>>> Although i have one issue.
>>>
>>> When i start qemu via libvirt with 16GB mem and 1G current mem:
>>> (...)
>>>    <memory unit='KiB'>16777216</memory>
>>>    <currentMemory unit='KiB'>1048576</currentMemory>
>>> (...)
>>>
>>> Qemu starts, and balloon can't free memmory, so guest doesn't boot (It
>>> hangs
>>> or is looped in ' virtio_balloon virtio2: Out of puff! Can't get 1
>>> pages').
>>> I think this is because dimm memmory is not yet onlined, and balloon
>>> already
>>> tries to shring memory in guest.
>>>
>>> Best regards
>>> Piotr Rybicki
>>>
>>>
>> - libvir@
>>
>> Please don`t top-post in technical mailing lists. Do you have a
>> crashkernel-reserved area there in the boot arguments? What
>> distro/guest kernel are running in this guest and what is dimm
>> configuration?
>>
>
> Hi.
>
> No, I don't have a crashkernel reserved area.
>
> But I've solved my problem. I load virtio-balloon device as a module
> (previously it was kernel built-in), and everything is working as expected.
>
> Thank You for Your attention.
>
> Best regards
> Piotr Rybicki

Thanks Piotr, the lack of the host-side memory shrinkage after balloon
deflation is interesting anyway, hopefully you may share guest` dmesg
bits from compiled-in balloon to check visible signs of the issue
(balloon should be initialized *before* DIMMs are being onlined, so
the behavior of the balloon itself it not clear at least for me).