Intel® Virtual RAID on CPU (Intel® VROC) VMD NVMe* RAID Manual Tuning of CPU Utilization

The Intel® VROC (VMD NVMe* RAID) package supports the ability for the user to adjust how much CPU utilization can be used by the Intel® VROC RAID engine.

When Intel® VROC (VMD NVMe* RAID) is installed, the registry key that controls this feature is installed. The default setting value of this registry key is 10. The range of values supported goes from 1 to 16 threads. If the user selects a value outside of that range, the Intel® VROC driver will automatically revert to the default value of 10. The Windows* registry key is the following:

• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\iaVROC\Parameters\Device\Threads

This registry setting means that the Intel® VROC RAID engine cannot exceed more than that number of CPU threads (in the default case, 10). That means that if further action is required, the Intel® VROC RAID engine will wait until one of those threads completes and is freed up. The default value was chosen because it is shown to be the most efficient in performance testing. However, every workload and setup are different. This allows platform manufacturers (and end-users) to tune this value for their usage.

Intel does not recommend changing this registry key unless the user has a full understanding of the following:

1. How to correctly modify a registry key.
2. Why the value is being changed.
3. Its corresponding impact on the platform operation.

If the number of threads is needed to be changed, it can be done in the registry to a maximum value of 32.