[Engine-devel] [vdsm] Proposal VDSM <=> Engine Data Statistics Retrieval Optimization

[Dan Kenigsberg]

On Fri, Mar 08, 2013 at 10:21:27AM +0800, Mark Wu wrote:
> On 03/07/2013 07:25 PM, Vinzenz Feenstra wrote:
> >Please find the prettier version on the wiki: http://www.ovirt.org/Proposal_VDSM_-_Engine_Data_Statistics_Retrieval
> >
> >
> >  Proposal VDSM - Engine Data Statistics Retrieval
> >
> >
> >    VDSM <=> Engine data retrieval optimization
> >
> >
> >      Motivation:
> >
> >Currently the RHEVM engine is polling the a lot of data from VDSM
> >every 15 seconds. This should be optimized and the amount of data
> >requested should be more specific.
> >
> If the data size really matters,  we could also consider to pack the
> information into binary.  I am not sure if it's suitable in the
> transmission of  XMLRPC.

I do not think we should embed binary in XMLRPC. I'd consider
compressing the data at the transport layer - but that would be a
completely deferent feature.

> >
> >For each VM the data currently contains much more information than
> >actually needed which blows up the size of the XML content quite
> >big. We could optimize this by splitting the reply on the
> >getVmStats based on the request of the engine into sections. For
> >this reason Omer Frenkel and me have split up the data into parts
> >based on their usage.
> >
> >This data can and usually does change during the lifetime of the VM.
> >
> >
> >        Rarely Changed:
> >
> >This data is change not very frequent and it should be enough to
> >update this only once in a while. Most commonly this data changes
> >after changes made in the UI or after a migration of the VM to
> >another Host.
> >
> >    *Status*  = Running
> >    *acpiEnable*  = true
> >    *vmType*  = kvm
> >    *guestName*  = W864GUESTAGENTT
> >    *displayType*  = qxl
> >    *guestOs*  = Win 8
> >    *kvmEnable*  = true #/*this should be constant and never changed*/
> Then it should be removed from vm stats. In my opinion, any
> information belongs to vm's static configuration, it shouldn't be
> included in vm stats. For the fields above, except 'Status',  engine
> can get the information without querying the vdsm host. It could not
> be changed by vdsm itself, right?

actually, guestName and guestOs may change - for example by installing
Linux on that Windows guest.