Windows 7 Power Management Power Management Improvements in Windows 7 Beta Published: April 2009 For the latest information, please see the Windows 7 Springboard web site (http://technet.microsoft.com/en-us/windows/dd361745.aspx). The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication. This white paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS DOCUMENT. Complying with all applicable copyright laws is the responsibility of the user. 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Contents Overview ..................................................................................................... 1 Reduced Power Consumption ......................................................................... 2 Idle Resource Utilization .......................................................................... 2 Trigger Start Services.............................................................................. 2 Enhanced Processor Power Management .................................................... 3 Timer Coalescing .................................................................................... 3 Device Power Management ...................................................................... 3 Adaptive Display Brightness ............................................................... 3 Low-Power Audio .............................................................................. 4 Bluetooth Power Improvements .......................................................... 4 Networking Power Improvements ........................................................ 4 Enhanced User Experiences ........................................................................... 5 Greater Enterprise Power Management ........................................................... 7 Power Efficiency Diagnostics..................................................................... 7 Group Policy ........................................................................................... 7 Windows Management Instrumentation ..................................................... 7 Power Policy ........................................................................................... 8 Ecosystem Engagement ................................................................................ 9 Customer Experience Improvement Program .............................................. 9 Tools and Documentation ........................................................................ 9 Active Partner Engagement ...................................................................... 9 Conclusion .................................................................................................. 10 More Information ........................................................................................ 11 1 Windows 7 Power Management Overview Today, organizations focus on power management as a way to reduce costs and decrease their carbon emissions. One way to reduce the cost of running client computers is to reduce the power that is consumed. Regulatory compliance and a focus on green information technology (IT) provide additional motivation to better manage power consumption. Also, IT pros need to quickly identify and resolve energy inefficiencies on individual computers—especially portable computers—to enable higher levels of productivity for their users. Multiple factors contribute to energy efficiency and portable computer battery life. A single component—whether a device, a device driver, the operating system, or an application— can significantly affect battery life. Optimizing for energy efficiency and battery life requires continuous investments by the entire ecosystem to ensure that platforms are optimally designed and configured. Microsoft is committed to making this ongoing investment to help extend battery life for portable computers and improve energy efficiency for all PCs and servers The Windows® 7 operating system provides several opportunities to decrease power consumption across the enterprise. The power management technologies in Windows 7 provide platform and processor efficiencies that reduce power consumption and can help lower energy costs. Windows 7 can also extend battery life for specific scenarios. Additionally, it provides diagnostic tools that enable OEM, IHVs, ISVs and IT pros to better manage and troubleshoot power management issues on computers and to extend the battery life for portable computers. This white paper describes power management enhancements in Windows 7, including improvements that reduce power consumption, enhance user experiences, and enable greater enterprise power management. 2 Windows 7 Power Management Reduced Power Consumption Microsoft designed Windows 7 with a strong focus on reducing the overall power consumption by investing in key areas of the platform including performance optimizations, idle resource utilization, device power management, and key end-user scenarios. Energy efficiency requires investments across the entire platform, not only in the core hardware or in the operating system. While Windows 7 can have a significant impact on platform energy efficiency, attached devices, and non-Microsoft and end-user applications, other platform extensions often have a larger total impact. The complexity and quantity of platform extensions require a broad approach to energy efficiency beyond focusing on a single component in the platform. In addition to core investments in Windows 7, Microsoft has emphasized ecosystem engagements for energy efficiency. Ecosystem partners, including IT pros, may leverage Windows 7 technical documentation, built-in diagnostic tools, and rich performance analysis tools to help identify issues across the enterprise. Idle Resource Utilization Idle efficiency is critical for the overall battery life of a PC because idle time dominates most scenarios. Reducing idle power consumption reduces the base power consumption. For example, if a portable computer uses 12 watts when the system is idle, all other scenarios increase power by some amount over the base 12 watts. Reducing idle power consumption benefits all other end-user workloads and scenarios, from DVD playback to office productivity. Reducing idle power consumption can be achieved by reducing the resource utilization of the system when it is idle. It can also be achieved by enabling the hardware to go into lower power states during long periods of inactivity. Resource utilization includes the processor, disk, memory, and network activity on the system. Windows 7 helps improve efficiency by reducing resource utilization when the system is idle. Reducing processor activity is particularly critical because of the large dynamic range of power consumption in modern processors. The typical portable computer processor consumes nearly 0 watts when idle, but it can consume up to 35 watts when fully utilized. Windows 7 provides greater idle efficiency by reducing (and in many cases eliminating) background activity on the system. Where periodic activity cannot be eliminated because of strict polling requirements (such as timers on the USB stack), Windows 7 exposes a new timer coalescing feature. (For more information, see ―Timer Coalescing API‖ later in this document). Timer Coalescing allows Windows 7 to align various background activities and execute them at the same time to keep the processor idle for longer periods of time. Additionally, Windows 7 defers non-critical background activity when the system is on battery power to help extend the battery life of a portable computer. Trigger Start Services System services often start automatically, run in the background, and wait for infrequent events to occur. Windows 7 can reduce background activities by trigger-starting system services, which starts background processes only when a specific event occurs. Events like device insertion and IP address changes can trigger-start services. For example, in Windows 7 the Windows Bluetooth service only