Windows® 7 and Windows Server® 2008 R2 include updated support for ACPI processor power management (PPM) features, including support for processor performance states and processor idle sleep states on multiprocessor systems. This paper provides details of the support in Windows 7 and Windows Server 2008 R2, describes how PPM functions with the Windows 7 and Windows Server 2008 R2 power policy store, and provides guidelines for firmware developers and system designers.
References and resources discussed here are listed at the end of this paper.
Introduction 5
Processor Power Management Changes in Windows 7 5
Windows 7 Processor Power Management Functional Overview 6
Fundamental Components 6
System Firmware (BIOS) 7
Windows Kernel Power Manager 8
Processor Drivers 8
Windows 7 Processor Driver Support 9
The Generic Processor Driver 9
Implementing Processor Power Management for Windows 7 10
Operating System Validation of ACPI Processor Objects 12
Declaring Processors 12
Implementing BIOS Support for Processor Performance States 12
Required Performance State ACPI Objects 12
Optional Performance State ACPI Objects 13
Describing Processor Control Dependencies 13
Implementing BIOS Support for Processor Idle States 14
C‑state Enumeration 14
Implementing BIOS Support for Processor Clock Throttling 16
T‑state Enumeration 16
Core Parking 17
Processor Clocking Control 18
Processor Power Management Validation Tools 19
Windows Resource Monitor 20
Windows Reliability and Performance Monitor 21
Viewing Processor Performance State Usage 21
Viewing Processor Idle State Usage 23
Event Viewer 24
PowerCfg 26
Pwrtest 26
Viewing Supported PPM States 26
Viewing and Logging Processor Idle State Transitions 27
Processor Power Policy on Windows 28
Usage Guidelines 29
Firmware Implementation of Processor Power Policy 29
Windows 7 Power Policy Store 30
Processor Power Policy Settings 31
Processor Performance Policy Settings 31
Processor Core Parking Policy Settings 36
Processor Idle Policy Settings 44
System Cooling Policy Setting 47
Next Steps 47
Resources 48