Embedded Linux Conference + Android Builders Summit

The Linux kernel provides a robust implementation of both the host and device side of USB. While we can all easily quote the theoretical throughput of each USB speed defined by the specifications, the numbers can be quite different in practice, with variation due to the device class and implementation, the format and structure of user data, and the implementations of both the driver and userspace software running on both the device and host. This presentation will explore some of the common pitfalls of USB software on both the device and host sides as it relates to performance and will show some techniques to maximize throughput. Analysis will be performed using several different USB device controllers. A USB hardware analyzer and ftrace with kernelshark will be used to find performance bottlenecks on both the the kernel and userspace sides in an interactive demonstration.