[ovirt-users] VM "hot" RAM memory decrease

[Martin Sivak]

Hi Nicolas,

KiB Mem tells you how much memory the host has. I am actually more
interested in the VM. Do you still have the mom.log from the time this
happened? We keep the logs for some time (they are rotated).

Best regards

Martin

On Wed, Mar 29, 2017 at 10:28 AM,  <nicolas at devels.es> wrote:
> El 2017-03-28 15:33, Martin Sivak escribió:
>>>
>>> min guaranteed should be respected, adding mom maintainer Martin
>>
>>
>> I can't really help without the mom.log and the virsh dumpxml output
>> of that VM in the final state (all memory ballooned).
>>
>> Min guaranteed should be respected, but the question is how the
>> physical memory was measured (which number from top was used).
>>
>> --
>> Martin Sivak
>> SLA / oVirt
>>
>
> Hi Martin,
>
> I tried to reproduce the issue again and I was unable to. I had a host with
> ~90% of RAM utilization and in mom.log I could see that ballooning was
> indeed happening, but I couldn't see a VM going under its minimum guaranteed
> threshold (at least not significantly).
>
> On top, I was using the 'KiB Mem' value to compare. I know this is in KiB
> and that oVirt has its values as MB in the webadmin, but when I sent this
> message the difference was quite more significant (1024MB of minimum
> guaranteed and about 640K KiB on the VM).
>
> It's also true that meanwhile we upgraded from 4.0.2 to 4.1.1 and this time
> I couldn't reproduce it anymore.
>
> If at some point I am able to reproduce it again, I'll send detailed logs of
> the issue.
>
> Thanks.
>
>
>> On Tue, Mar 28, 2017 at 4:29 PM, Michal Skrivanek
>> <michal.skrivanek at redhat.com> wrote:
>>>
>>>
>>>> On 27 Mar 2017, at 23:15, Nicolás <nicolas at devels.es> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I don't really know if this question is suitable on this list, as I
>>>> doubt it's an oVirt bug, neither I know if it shall be considered a bug.
>>>>
>>>> We recently run a VM on a host that was memory over-used (around 80% of
>>>> usage). The VM booted correctly, then we run "top" and saw how physical RAM
>>>> started decreasing every two seconds. At first it was 4GB, then less and
>>>> less until it stabilized at around 600MB.
>>>>
>>>> Based on this (correct me if I'm wrong), we believe this is an effect of
>>>> having this VM with ballooning enabled, as it does exactly this: It
>>>> adds/removes RAM depending on host decision. Thing is that this VM had a
>>>> minimal guaranteed RAM of 1GB, so even if this happened due to ballooning,
>>>> I'm not sure if it should have honored the minimum guaranteed RAM.
>>>>
>>>> When this happened, we run a 'ps' to see with what options the qemu
>>>> process was invoked, and parameters seemed correct (that's why I don't know
>>>> if it should be posted here or even if it's a bug).
>>>
>>>
>>> It does belong here, it’s a different component doing it “externally” to
>>> the qemu process- mom.
>>>
>>>>
>>>> Is this the expected behavior?
>>>
>>>
>>> min guaranteed should be respected, adding mom maintainer Martin
>>>
>>> Thanks,
>>> michal
>>>
>>>>
>>>> Thanks.
>>>> _______________________________________________
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>>>>
>>>>
>>>
>