Hi Kaitlin,
Hi Dayne,
Let me sort of work backwards here..
Currently, on this system ConsumableBlocks represent MemTotal or the current memory allocated to the guest, even though it is not completely accurately representing the free memory on Dom0 that is available to new DomUs. The issue is that between version 0.4.1 and 0.5.2 NumberOfBlocks for a Dom0 changed to be MaxInt. It used to match ConsumableBlocks.
In your original e-mail you said: "NumberOfBlocks: max amount of memory that can be allocated to a guest ConsumableBlocks: current memory allocated to the guest" This would mean that for a Dom0, according to the following output: $ virsh dominfo Domain ... Max memory: no limit Used memory: 6595584 kB ... Which seems to indicate that: NumberOfBlocks -> no limit (or max int as a reasonable representation) ConsumableBlocks -> 6595584 / 4096 blocks Which are the values I get in 0.5.2.
Correct - that's what the bug is here. A regression was introduced.
Arguably, there may be a bug in that maxInt is the "max amount of memory that can be allocated to a guest" for Dom0. However, libvirt does report that there is "no limit" for Dom0. The change between versions, if it is a regression, is that 0.5.2 is representing "no limit" by maxInt where 0.4.1 represented it as "current memory allocated to ..." Dom0, or the MemTotal on Dom0.
In 0.4.1: -NumberOfBlocks the memory currently assigned to the guest -ConsumableBlocks the maximum memory allocated to the guest\
Isn't this backwards from your original message? Or did I just misunderstand? Interestingly, what I see for a DomU with maxmem=1024 and memory=512 in 0.4.1 is the following: -ConsumableBlocks=262144 -NumberOfBlocks=131072 -BlockSize=4096 Which is consistent with what you just stated about 0.4.1 and reverse of what you said in your original response.
In 0.5.2: -NumberOfBlocks the maximum memory allocated to the guest -ConsumableBlocks the memory currently assigned to the guest
What I see in 0.5.2 for a DomU with maxmem=1024 and memory=512 is: -ConsumableBlocks=131072 -NumberOfBlocks=262144 -BlockSize=4096 I am pretty new at deciphering MOF files, but if I understand the mof, NumberOfBlocks should be the maximum as in the NumberOfBlock x BlockSize = total size of memory (I think this mean maximum memory). I believe the MOF says ConsumableBlocks is the number of blocks available for consumption, or the actual memory assigned to the guest. If I understand this right, it is actually 0.4.1 that is reversed and 0.5.2 contains the correction, yes? In either case I am going to have to figure out how to tell if I am talking to a 0.4.1 libvirt-CIM or 0.5.2 .. and where the change happened .. *sigh* ... so I can handle it appropriately as one of them is not right.
So this should definitely be fixed since we aren't adhering to the definitions in the mof...
I think there is something else going on here. As far as I can tell the numbers are not swapped. Here is what I think is going on. The NumberOfBlock x BlockSize equates to about 16TB (not what my system
Ah, my mistake. When I read your previous message, I thought you were talking about the issue above.
I thought I was talking about the same issue :-). This is quite confusing.
The values do seem strange. We use the following calculation:
NumberOfBlocks = (max_mem * 1024) / BlockSize ConsumableBlocks = (used_mem * 1024) / BlockSize
For DomU this seems to be what I am seeing.
Agreed - NumberOfBlocks is puzzling: (4294967040 / 1024) * 4096 = 17179865088 KB
For Dom0 this seems to be a new behavior somewhere between 0.4.1 and 0.5.2. I am fine with this as there really is not maximum and it appears the max is possibly represented by maxInt (seeing how virsh show it as "no limit").
ConsumableBlocks is correct though: (6595584 * 1024) / 4096 = 1648896
What does "xm list -l Domain-0" return for memory and maxmem? I don't have a Xen system with that much mem to test on.
On the host with libvirt-CIM 0.5.2 / libvirt 0.4.6 $ xm list -l Domain-0 | grep -i mem (maxmem 16777215) (memory 6441) (shadow_memory 0) xm list -l sles11-HVM | grep -i mem (maxmem 1024) (memory 512) (shadow_memory 0) On the host with libvirt-CIM 0.4.1 / libvirt $ xm list -l Domain-0 | grep -i mem (memory 3621) (shadow_memory 0) (maxmem 3621) $ xm list -l target | grep mem (memory 512) (shadow_memory 9) (maxmem 1024) It looks like you are just reporting what libvirt is telling you ... very interesting. BTW: I don't actually have 16Tb of memory either, I only have 8Gb. It looks like we are honing in on the problem. Based on everything I said above, I believe libvirt-CIM 0.4.1 to be flawed and libvirt-CIM 0.5.2 to be correct. Does this sound about right? Do you have any idea where it may have changed? Thanks for your patience. Dayne
has - my system only has 8GB). If you look at virsh dominfo Domain- 0 on my box I get:
Max memory: no limit Used memory: 6595584 kB
If NumberOfBlocks is MaxInt (of some sort) than this would make some sort of sense and ConsumableBlocks contains the correct value. It is a little bit misleading since processes in Dom0 take memory away from what can be allocated to a DomU. This is evident from this /proc/meminfo snippet:
MemTotal: 6595584 kB MemFree: 5940684 kB Buffers: 16112 kB Cached: 264716 kB SwapCached: 0 kB Active: 138332 kB Inactive: 216032 kB SwapTotal: 2626544 kB SwapFree: 2626544 kB Dirty: 436 kB ... VmallocTotal: 34359738367 kB VmallocUsed: 267184 kB VmallocChunk: 34359470859 kB DirectMap4k: 8066284 kB DirectMap2M: 0 kB
The current WBEM values:
-ConsumableBlocks=1648896 -NumberOfBlocks=4294967040 -BlockSize=4096
Kaitlin,
Thanks for the correction. It seems were trying to use these
Medlyn, Dayne (VSL - Ft Collins) wrote: properties correctly and there is something just not right. Using
same wbemcli command I get:
-SystemCreationClassName="Xen_ComputerSystem" -SystemName="Domain-0" -CreationClassName="Xen_Memory" -DeviceID="Domain-0/mem"
-ConsumableBlocks=1717760 -NumberOfBlocks=4294967040 -BlockSize=4096 Yes, that's definitely a bug. The values for ConsumableBlocks and NumberOfBlocks should be swapped. I'd hoped to have a bugfix out today, but it looks like it'll be tomorrow.
I think there is something else going on here. As far as I can tell
Medlyn, Dayne (VSL - Ft Collins) wrote: the the numbers are not swapped. Here is what I think is going on. The NumberOfBlock x BlockSize equates to about 16TB (not what my system has - my system only has 8GB). If you look at virsh dominfo Domain-0 on my box I get:
Max memory: no limit Used memory: 6595584 kB
If NumberOfBlocks is MaxInt (of some sort) than this would make some
sort of sense and ConsumableBlocks contains the correct value. It is a little bit misleading since processes in Dom0 take memory away from what can be allocated to a DomU. This is evident from this /proc/meminfo snippet:
MemTotal: 6595584 kB MemFree: 5940684 kB Buffers: 16112 kB Cached: 264716 kB SwapCached: 0 kB Active: 138332 kB Inactive: 216032 kB SwapTotal: 2626544 kB SwapFree: 2626544 kB Dirty: 436 kB ... VmallocTotal: 34359738367 kB VmallocUsed: 267184 kB VmallocChunk: 34359470859 kB DirectMap4k: 8066284 kB DirectMap2M: 0 kB
The current WBEM values:
-ConsumableBlocks=1648896 -NumberOfBlocks=4294967040 -BlockSize=4096
Currently, on this system ConsumableBlocks represent MemTotal or the
current memory allocated to the guest, even though it is not completely accurately representing the free memory on Dom0 that is available to new DomUs. The issue is that between version 0.4.1 and 0.5.2 NumberOfBlocks for a Dom0 changed to be MaxInt. It used to match ConsumableBlocks. I don't think there is an issue and I can work with this now that I understand it.
As you point out below, I am probably not going to be able to get the
information I want out of Xen_MemoryPool.
Thanks for your help and insight.
Dayne
One difference I did notice is that we are trying to use these
from Dom0 to determine the amount of available memory for guests to use. Perhaps for Dom0 these values just map differently.
My objective is to identify how much memory is available on the hypervisor that can be allocated to new guests. Looking more closely, I wonder if we should be using Xen_MemoryPool somehow to do this instead. What is the relationship between the Capacity and Reserved properties? I have not quite been able to make sense out of what
values mean. What I have noticed is that a host with no defined guests starts with Reserved smaller than Capacity:
-PoolID="MemoryPool/0" -Primordial=FALSE -Capacity=8385536 -Reserved=8064748 -ResourceType=4 -OtherResourceType= -ResourceSubType= -AllocationUnits="KiloBytes"
As guests are create and start the Reserved count increases and grows beyond the capacity. I am not quite sure how to make use of this information. Do you have any insights?
The Capacity value is the memory value libvirt reports for the host (you'd also get this value if you use: virsh nodeinfo).
The Reserved value is the some of all the memory that is currently allocated to the guests on the system (as reported by libvirt). This includes guests that aren't running, which is why you are seeing the value grow beyond capacity.
We don't represent the host capabilities, but in the case of Xen, you can get around that by pulling some things from Dom0.
However, using Dom0's attribute may not give you the full picture you're looking for. I would suggest taking a look at a provider set that represents the host information. Something like the sblim-base providers should this info.
Dayne
-----Original Message----- From: libvirt-cim-bounces@redhat.com [mailto:libvirt-cim- bounces@redhat.com] On Behalf Of Kaitlin Rupert Sent: Wednesday, May 13, 2009 7:10 PM To: List for discussion and development of libvirt CIM Subject: Re: [Libvirt-cim] What does NumberOfBlocks and ConsumableBlocks in theXen_Memory class represent?
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
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
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
values these libvirt- possible 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_Memo
ry",DeviceID="rstest_domain/mem",SystemCreationClassName="Xen_ComputerS
ystem",SystemName="rstest_domain"' -nl
localhost:5988/root/virt:Xen_Memory.CreationClassName="Xen_Memory",Devi
ceID="rstest_domain/mem",SystemCreationClassName="Xen_ComputerSystem",S
ystemName="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@linux.vnet.ibm.com
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