Updated: October 19, 2012
Core Parking is a Windows kernel power manager and kernel scheduler technology that helps improve the energy efficiency of a system by dynamically scaling the number of logical processors that are in use based on workload. Similar to how processor performance states help scale the performance of a single processor, Core Parking is designed to help scale the performance and energy efficiency across the set of logical processors in the system.
This information applies to the following operating systems:
- Windows Server 2008 R2
- Windows 7
When the Core Parking algorithm reduces the number of logical processors that are in use, it parks some of the logical processors in the system. The kernel scheduler correspondingly gives preference to unparked logical processors rather than parked logical processors when it schedules any non-affinitized threads. This lets the parked logical processors become idle, which in turn lets the corresponding processor cores transition into a lower power idle state.
Core Parking is most effective on systems that have processor idle states with extremely low power consumption. When combined with ITTD, Core Parking helps reduce the amount of interrupt activity on systems that run Hyper-V. On systems with processors that include Intel Hyper-Threading Technology, Core Parking is also leveraged to help intelligently schedule work between threads that are running on multiple logical processors in the same processor core.
Microsoft has engaged with leading processor vendors to tune the Core Parking policy defaults. System manufacturers are encouraged to change the Core Parking policy parameters only with detailed consultation from the system processor vendor.
Core Parking is supported only on Windows Server 2008 R2. However, the Core Parking algorithm and infrastructure is also used to balance processor performance between logical processors on Windows 7 client systems with processors that include Intel Hyper-Threading Technology.