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Users can also set CPU pinning topology from the resource allocation tab of the VM. Figure 16 shows the settings based on the example above.
Figure 16. CPU pinning topology as displayed by VM configuration in UI
The following syntax can be used when manually setting CPU pinning:
Table 2. CPU pinning topology Format: v#p[_v#p]
Example | Description |
0#0 | Pin vCPU 0 to pCPU 0 |
0#0_1#3 | Pin vCPU 0 to pCPU 0 and Pin vCPU 1 to pCPU 1 |
1#1-4,^2 | Pin vCPU 1 to pCPU set to 1 to 4, excluding 2 |
In addition to manual pinning, the UI offers the following automated options which are defined in Figure 17:
Figure 17. Automated settings for CPU pinning in the UI
For example, if Isolate Threads is selected, each virtual CPU will be tied to a unique physical CPU. Using the same VM as in the manual example, Isolate Threads was used and then the VM re-started. Figure 18 shows that each vCPU was assigned a unique physical CPU:
Figure 18. Isolate Threads example
While CPU pinning can help ensure that a VM gets dedicated resources, there are some caveats the user needs to be aware of. While these are detailed in Oracle’s pinning documentation previously referenced, one restriction is worth emphasizing. Oracle does not permit live migration of VMs that have pinned CPUs. If those VMs are on shared storage in an Oracle Linux KVM cluster, there can be no scheduling policy in Oracle Linux Virtualization Manager. A good use case, however, is Oracle Real Application Clusters (RAC) because the VMs should be deployed on their own Linux KVM host and not moved. The Oracle RAC instances are what provide HA, not the Linux KVM hosts.
Note: While online VM migration is not supported with CPU pinning, it is possible to move an Oracle RAC One instance between nodes so long as the nodes contain licensed Oracle Database software.