[ovirt-users] hot plug memory in el7

Thu Dec 10 11:24:36 UTC 2015

> On 10 Dec 2015, at 11:30, Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:
> 
> On Thu, Dec 10, 2015 at 10:41 AM, Michal Skrivanek <mskrivan at redhat.com> wrote:
> 
>> On 10 Dec 2015, at 00:11, Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:
>> 
>> On Wed, Dec 9, 2015 at 10:21 PM, Sandro Bonazzola  wrote:
>> 
>> 
>> No idea. If it's libvirt issue, can you test http://cbs.centos.org/koji/buildinfo?buildID=4726 ? it's from centos virt sig, introduced for Xen but should work on kvm as well. or the 7.2 libvirt from http://mirror.centos.org/centos/7/cr/x86_64/Packages/.
>> 
>> 
>> 
>> 
>> Then I reboot my HV, exit from maintenance, connect to engine and start VM.
>> VM situation
>> $ free
>>               total        used        free      shared  buff/cache   available
>> Mem:        8172900      147356     7875692        8480      149852     7847248
>> Swap:        839676           0      839676
>> 
>> I set memory from 8192Mb to 10240Mb
>> I get the same window I got with previous libvirt version.
>> I select OK (I don't select "Apply later" checkbox)
>> 
>> Inside guest there is no changed memory, but I can see this in /var/log/messages:
> 
> could it be perhaps the guest has troubles recognizing hotplug? Is it also a CentOS 7.1 guest?
> 
> Yes, CentOS 7.1 updated up to a couple of days ago.

Can you try 7.2? I don’t remember exactly but it may be that in earlier guests it’s not automatic. Check some tips for onlining memory explicitly

5.2. How to online memory
 ------------
Even if the memory is hot-added, it is not at ready-to-use state.
For using newly added memory, you have to "online" the memory block.

For onlining, you have to write "online" to the memory block's state file as:

% echo online > /sys/devices/system/memory/memoryXXX/state

> 
>   
> 
>> 
>> Dec  9 23:56:18 racclient1 kernel: init_memory_mapping: [mem 0x240000000-0x2bfffffff]
>> 
>> ANd output of dmesg contains:
>> 
>> [  219.363640] ACPI: \_SB_.MP00: ACPI_NOTIFY_DEVICE_CHECK event
>> [  219.364248] init_memory_mapping: [mem 0x240000000-0x2bfffffff]
>> [  219.364253]  [mem 0x240000000-0x2bfffffff] page 2M
>> [  219.366773]  [ffffea0009000000-ffffea00091fffff] PMD -> [ffff8800b7e00000-ffff8800b7ffffff] on node 0
>> [  219.368433]  [ffffea0009200000-ffffea00093fffff] PMD -> [ffff880231400000-ffff8802315fffff] on node 0
>> [  219.369838]  [ffffea0009400000-ffffea00095fffff] PMD -> [ffff880233600000-ffff8802337fffff] on node 0
>> [  219.371226]  [ffffea0009600000-ffffea00097fffff] PMD -> [ffff880233000000-ffff8802331fffff] on node 0
>> [  219.372790]  [ffffea0009800000-ffffea00099fffff] PMD -> [ffff880232c00000-ffff880232dfffff] on node 0
>> [  219.374185]  [ffffea0009a00000-ffffea0009bfffff] PMD -> [ffff880232200000-ffff8802323fffff] on node 0
>> [  219.377349]  [ffffea0009c00000-ffffea0009ffffff] PMD -> [ffff8800b7400000-ffff8800b77fffff] on node 0
>> [  219.378716]  [ffffea000a000000-ffffea000a1fffff] PMD -> [ffff8800b7000000-ffff8800b71fffff] on node 0
>> [  219.380115]  [ffffea000a200000-ffffea000a3fffff] PMD -> [ffff880230c00000-ffff880230dfffff] on node 0
>> [  219.388147]  [ffffea000a400000-ffffea000abfffff] PMD -> [ffff880227c00000-ffff8802283fffff] on node 0
>> [  219.389687]  [ffffea000ac00000-ffffea000adfffff] PMD -> [ffff8800b7200000-ffff8800b73fffff] on node 0
> 
> but “free” sstill shows the same value as before hotplug?
> 
> 
> Yes, output of "free" command show the same amount of memory
> 
>   
> 
>> 
>> I then shutdown the VM and power on it again and I get the changed memory:
> 
> well, yeah, but that doesn’t count since you’ve shut it down, so the next run is initialized with 10GB
> 
> 
> It was only to verify that after shutdown/power on the changed setting would have been applied to the VM
>  
>> $ free
>>               total        used        free      shared  buff/cache   available
>> Mem:       10237276      167872     9919656        8480      149748     9891280
>> Swap:        839676           0      839676
>> 
>> BTW: When I press ok in the gui for memory increase I get these events in webadmin:
>> Dec 9, 2015 11:56:22 PM
>> VM racclient1 c71_Disk1_newtemplate disk was updated by admin at internal.
> 
> hm..doesn’t sound right. Did the confirmation window show any more fields as changed other than memory?
> 
> The window I got when I increased the amount of memory was the same as in a previous test where I selected "Cancel", before libvirt update; see
> https://drive.google.com/file/d/0BwoPbcrMv8mvbUw2VnpCMTNNQlU/view?usp=sharing
> 
> And I also commented about misleading information inside it: I didn't clearly understand what would have been changed and what not, because I see memory information in both parts…..

I agree it’s confusing. Please do open a bug on that

Thanks,
michal

> 
>> 
>> It doesn't seem as expected, does it?
> 
> I think we’re almost there. Just need to figure out what happened in the guest. I would suspect a problem there
> 
> Thanks,
> michal
> 
>> Gianluca
>> 
> 
> 
> 
> The gui events have the same timestamp of the moment when I pressed ok. After 2-3 minutes I did shutdown and power on of the VM and I only got the down/up events...
> I'm available to make further test you need.
> 
> GIanluca 
> 