[Libvirt-cim] What does NumberOfBlocks and ConsumableBlocks in theXen_Memory class represent?

[Kaitlin Rupert]

Medlyn, Dayne (VSL - Ft Collins) wrote:
> All,
> 
> I am trying to understand the use of NumberOfBlocks and ConsumableBlocks in the Xen_Memory class, specifically for the Xen host.  
> What I have noticed is that between libvirt-cim-0.4.1 and libvirt-cim-0.5.2 the values for NumberOfBlock is now different than ConsumableBlocks and 
 > much larger than the physical memory installed on the system.
> Is it the case that NumberOfBlocks represents the maximum possible blocks for the  hardware,
 > or some such number ConsumableBlocks is the memory that is
> actually installed in the system? On my system, however, NumberOfBlocks reports 16TB where /proc/meminfo
> reports 32Tb for VmallocTotal.  In short, should I be using ConsumableBlocks to determine the total physical memory on the system?


Hi Dayne,

It looks like there is a bug here.  Currently, the providers use the 
following representation:

NumberOfBlocks:   max amount of memory that can be allocated to a guest
ConsumableBlocks: current memory allocated to the guest

However, these values should be reversed based on the attribute 
definitions.

Here's an example using one of the guests on my system:

# virsh dominfo rstest_domainId:             -
Name:           rstest_domain
UUID:           746de06d-cb45-4efd-bc18-bf91d10bec84
State:          shut off
CPU(s):         1
Max memory:     131072 kB
Used memory:    130048 kB
Autostart:      disable

We take the max and used memory values libvirt reports and then convert 
them based on the block size.

# wbemcli gi 
'http://localhost:5988/root/virt:Xen_Memory.CreationClassName="Xen_Memory",DeviceID="rstest_domain/mem",SystemCreationClassName="Xen_ComputerSystem",SystemName="rstest_domain"' 
-nl
localhost:5988/root/virt:Xen_Memory.CreationClassName="Xen_Memory",DeviceID="rstest_domain/mem",SystemCreationClassName="Xen_ComputerSystem",SystemName="rstest_domain"
<snip>

-TransitioningToState=12
-SystemCreationClassName="Xen_ComputerSystem"
-SystemName="rstest_domain"
-CreationClassName="Xen_Memory"
-DeviceID="rstest_domain/mem"

<snip>

-BlockSize=4096
-NumberOfBlocks=32768
-ConsumableBlocks=32512

<snip>
-- 
Kaitlin Rupert
IBM Linux Technology Center
kaitlin at linux.vnet.ibm.com