[Openstack] Improving Xen support in the libvirt driver

Muriel mucawhite at gmail.com
Thu May 10 15:33:53 UTC 2012


Il 10/05/2012 16:08, Alvaro Lopez ha scritto:
> On Thu 10 May 2012 (15:17), Muriel wrote:
>> Great! But there is a reason if are you using /proc/meminfo instead
>> of getInfo when calculating the memory used?
>> You know if there is a way to get, using libvirt, the reserved
>> memory for dom0? Or the only solution is to read the configuration
>> file of xen?
> I calculated the memory looking into /proc/meminfo because if the memory
> is not limited (i.e. no dom0_mem option) the dom0 might take all the
> memory available, that then will be ballooned out. For example, in a
> machine with 16GB RAM you could have:
>
>    # xm li
>    Name                                        ID   Mem VCPUs      State   Time(s)
>    Domain-0                                     0 15030     8     r-----   1312.8
>
> If you query libvirt for the dom0 mem, the free memory will be around
> 1GB, but you can create a machine with more RAM (since ballooning is
> enabled):
>
>    # xm li
>    Name                                        ID   Mem VCPUs      State   Time(s)
>    Domain-0                                     0  9188     8     r-----   1328.6
>    test                                         4  7000     4     -b----   3.5
>
> If the dom0 memory is fixed and ballooning is disabled, then yes, you
> can query libvirt directly.
>
> Regards,
Thank you for remarking this point, sometimes I forget the balooning 
system :).
I messed up the question: if you consider the case where the memory is 
limited (dom0_mem) the value of MemTotal in meminfo is wrong. Do you 
think it makes sense to take the total memory value from libvirt and 
from meminfo the rest?
Thus it should work in both cases.

Thanks,
M.




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