Proposal VDSM - Engine Data Statistics Retrieval

== VDSM <=> Engine data retrieval optimization ==

Motivation:

Currently the oVirt Engine is polling a lot of data from VDSM every 15 seconds. This should be optimized and the amount of data requested should be more specific.

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 needs of the engine into different requests. For this reason Omer Frenkel and me have split up the data into parts based on their usage.

Changes

New Verbs

getAllVmRuntimeStats

Get runtime information of all VMs Returns for each VM a map with UUID and a value of:

  • @cpuSys Ratio of CPU time spent by qemu on other than guest time
  • @cpuUser Ratio of CPU time spent by the guest VM
  • @memUsage The percent of memory in use by the guest
  • @elapsedTime The number of seconds that the VM has been running
  • @status The current status of the given VM
  • @statsAge The age of these statistics in seconds
  • @hashes Hashes of several statistics and information around VMs

Hashes consists of:

  • @info Hash for VmConfInfo data
  • @config Hash of the VM configuration XML
  • @status Hash of the VmStatusInfo data
  • @guestDetails Hash of the VmGuestDetails data
getVmStatus

Get status information about a list of VMs Parameters:

  • @vmIDs a list of UUIDs for VMs to query

Returns for each VM in vmIDs a map with UUID and a value of:

  • timeOffset The time difference from host to the VM in seconds
  • monitorResponse Indicates if the qemu monitor is responsive
  • clientIp The IP address of the client connected to the display
  • username the username associated with the current session
  • session The current state of user interaction with the VM
  • guestIPs A space separated string of assigned IPv4 addresses
  • pauseCode Indicates the reason a VM has been paused
getVmConfInfo

Get configuration information about a list of VMs Parameters:

  • @vmIDs a list of UUIDs for VMs to query

Returns for each VM in vmIDs a map with UUID and a value of:

  • acpiEnable Indicates if ACPI is enabled inside the VM
  • displayPort The port in use for unencrypted display data
  • displaySecurePort The port in use for encrypted display data
  • displayType The type of display in use
  • displayIp The IP address to use for accessing the VM display
  • pid The process ID of the underlying qemu process
  • vmType The type of VM
  • kvmEnable Indicates if KVM hardware acceleration is enabled
  • cdrom optional The path to an ISO image used in the VM’s CD-ROM device
  • boot optional An alias for the type of device used to boot the VM
getAllVmDeviceStats

VM device statistics containing information for getting statistics and SLA information Returns for each VM a map with UUID and a value of:

  • memoryStats Memory statistics as reported by the guest agent
  • balloonInfo Guest memory balloon information
  • disksUsage Info about mounted filesystems as reported by the agent
  • network Network bandwidth/utilization statistics
  • disks Disk bandwidth/utilization statistics
getVmGuestDetails

Get details from the guest OS from a list of VMs Parameters:

  • @vmIDs a list of UUIDs for VMs to query

Returns for each VM in vmIDs a map with UUID and a value of:

  • appsList A list of installed applications with their versions
  • netIfaces Network device address info as reported by the agent

Usage

Currently the engine is requesting currently every 3 seconds the vm list from each vdsm host and every 15 seconds all the data mentioned above for all VMs.

The change would be as follows:

The engine requests every 3 seconds getAllVmRuntimeStats from vdsm which will give the engine the most used data. If the engine has a mismatch of the hashes returned by getAllVmRuntimeStats it should request the data changed.

if hashes.info changed => request getVmConfInfo with all vmIDs on that host where the hash changed if hashes.status changed => request getVmStatus with all vmIDs on that host where the hash changed if hashes.guestDetails changed => request getVmGuestDetails with all vmIDs on that host where the hash changed

Request getAllVmDeviceStats periodically e.g. every 5 minutes, which should be sufficient for the DWH, in case it is not it could be even configurable.