T-kernel: Providing Reliable OS Support to Wireless Sensor Networks

摘要

The development of a reliable large-scale wireless sensor network (WSN) is very difficult because of resource constraints, energy budget, and demanding application requirements. Three OS features OS protection, virtual memory, and preemptive scheduling can significantly improve the reliability of WSN systems and facilitate developing complex WSN software. However, due to the lack of hardware support for privileged execution and address translation, it is impossible to implement these features with traditional OS design techniques. To solve this problem, we design a new OS kernel, the t-kernel, to perform extensive code modification at load time. The modified code and the OS work in a collaborative way supporting the aforementioned features. Having implemented the t-kernel on MICA2 motes, we evaluate its performance by measuring the overhead and execution speed. We analyze the CPU utilization of sensor network applications, and verify that, though CPU-bound tasks execute 1.5 3 times as long as in native mode, application performance under typical workloads does not noticeably degrade. The t-kernel significantly enhances developers ability to design reliable and sophisticated sensor networks, and includes several new design techniques, such as efficient binary translation on highly constrained sensor nodes, differentiated virtual memory without repeatedly writable swapping devices, and the protection of the OS from application errors without privileged execution hardware.