Manage Extended CPU Flags for Compute Zone

OnApp introduces a possibility to use extended CPU flags for compute resources.  Enabling extended CPU flags will increase performance and functionality of processors.  This functionality is implemented on a per compute zone basis. When enabled per compute zone and properly configured, all compute resources in that zone will inherit the specified extended CPU flags. Hot migration inside such compute zones is more reliable. This feature also allows you to set bigger prices for the better CPUs in billing plans.

  • It is important that you evaluate the risks of CPU flags misconfiguation before enabling the functionality. Make sure that the list of extended CPU flags that you select is reasonable.
  • CPU flag's functionality is relevant to KVM compute resources only. We do not recommend creating mixed XEN/KVM compute zones for better performance.
  • When switching on extended CPU flags for compute zone, go through the already existing compute recources to switch off conflicting flags.

Below you can find instructions on how to set and use CPU flags.

On this page:

Enable CPU flags for compute zone


 

You can enable extended CPU flags functionality for a compute zone:

After extended CPU flags functionality is enabled for a compute zone, all compute resources in this zone will use the CPU flags set up for the zone. If no CPU flags are set (for example you haven't configured them yet), then no extended CPU flags are enabled for compute resources in this zone.

Now proceed to Manage CPU flags page. 

Manage CPU flags


 

After extended CPU flags functionality is enabled for compute zone, configure the list of enabled CPU flags:

  1. Go to your Control Panel's Settings menu and click the Compute Zones icon.
  2. Click the label of the Compute zone you want to manage CPU flags for.
  3. On the screen that appears, click the Manage CPU Flags link in the Tools section.
  4. On the screen that follows you'll see the list of CPU flags that are common for all the compute resources. Also you will see the list of conflicted CPU flags (if any).

  5. Click the Edit icon. The list of all the flags that are common for all compute resources in a zone will be displayed.

  6. Click a flag to enable or disable it. Enabled flags are marked in green, disabled flags are grayed out.
  7. Click Submit.
  • If there are conflict flags (those which are not available to some compute resources in this compute zone, but this compute resource is forcefully added to compute zone), they are marked red.
  • If the compute zone has already configured CPU flags, and then one of the compute resources of this zone goes to maintenance mode, there are several scenarios when it goes back online. For more information refer to the Maintenance Mode for Xen/KVM Compute Resources section of this guide.
  • Be careful when adding new compute resources to a compute zone with enabled and configured extended CPU flags. For more info, refer to the following section.

Adding new compute resources to compute zone with already configured set of flags


 

There are several scenarios when new compute resources are added to compute zone with already configured set of flags:

  • If the new compute resource has the same CPU as those which are already in a compute zone, no problems should occur. The new compute resource will inherit the CPU flags set per compute zone.

  • If the new compute resource has the CPU with better performance than those which are already in a compute zone, the new compute resource will inherit the CPU flags set per zone. The other flags will be disabled.

  • If the new compute resource has the CPU with worse performance than those which are already in a compute zone, the new compute resource cannot inherit all the CPU flags set per zone, as most probably some of them are missing for this new compute resource.  In this case you will be alerted on inconsistency and you will have to make a decision if such compute resource should be added to zone. When you add a compute resource to a compute zone a warning pops up with the info that some flags of this new compute resource are missing. You make a decision to cancel the adding a compute resource to a compute zone, or agree despite the current zone configuration may be broken to proceed adding this compute resource anyway. If you agree, the compute resource is added to a compute zone and you are warned that it is required to manage flags to fix. In this case, go to the Settings > Compute zones > compute zone label > Tools > Manage CPU flags page to switch off the redundant flags. The flags managing page will show the list of flags divided into three columns:Enabled/Disabled/Conflict. You decide which flags to switch on/off.