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Vampire Mice: How USB PM impacts you

Project: Linux USB kernel support

Did you know that your innocent USB mouse is actually a power-hungry battery-draining monster? This talk explores the impact of USB devices on platform power consumption, and introduces some cool new power features in the Intel Ivy Bridge and Haswell USB host controllers.

USB devices have always been battery eaters. A single active USB device will prevent runtime PM of USB host controllers, keep the CPU in higher C-states, and keep the system out of the new Intel S0i3 sleep states. This talk will cover tools that can enable USB power management, including the USB power sysfs interface and the USB power options in PowerTop 2.0. We'll also touch on the horrid little USB devices that break when power management is turned on, and how Linux customers can avoid purchasing them.

We'll also cover some cool new USB power management features that Intel has been stuffing into their Ivy Bridge and Haswell chipsets. Ivy Bridge includes support for USB 3.0, and the new "Link Power Management" feature that allows individual links in the USB bus to power down. Haswell includes support for a cool new mechanism to completely turn off USB ports, and a way to place the USB host controller into the deepest PCI power savings state (D3cold).

The aim of this talk is to educate users on how USB devices impact their battery life, and to introduce them to cool power savings on new and future Intel systems. This talk targets all users, but will provide deep dives into technical details for the more advanced users.

Sarah Sharp

Sarah Sharp is the maintainer for Linux USB 3.0 support, and has been contributing to USB power management for five years. She is a software engineer at Intel's Open Source Technology Center.

In her spare time, Sarah Sharp hacks on a set of open source tools for gardeners (http://github.com/sarahsharp/GardenGeek). Sarah lives in the bike-friendly city of Portland, Oregon, with her husband, two cats, a giant garden, and a beehive. Sarah is also a member of Portland's Code 'N Splode group, which is a women and women-identifying coder's group.