This paper focuses on the behavior of devices that causes a significant increase to system power. Unfortunately, today's systems are not optimized for situations where devices either generate power-unfriendly traffic patterns or do not support baseline mobile platform features such as link power management or intelligent traffic management.
The first section of this paper covers key concepts of modern-day multicore platform power management works, with real-world data to illustrate the power impact of ill-behaved devices on platforms. The second section focuses on PCI Express Base Specification 2.0 (PCIe) and some of the key challenges observed, with recommendations including link state support, local power management policy, and production of activity patterns that help facilitate good platform energy efficiency. The third section focuses on USB 2.0, with recommendations including dynamic asynchronous scheduler management, conveying interrupt information through periodic endpoints, and the proper use of selective suspend.
This information applies for the following operating systems: Windows Server 2008 Windows Vista Microsoft Windows Server 2003 Microsoft Windows XP Microsoft Windows 2000
Included in this white paper:
Responsiveness vs. Battery Life
Energy-Efficient Device Recommendations
Bus Traffic Alignment
PCI Express Link Power Management
USB 2.0 Full- and Low-Speed Data Patterns
USB 2.0 High-Speed Data Patterns
Networking Device Recommendations
Streaming Device Recommendations
Human Interface Device Recommendations
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