Dynamic priority boosting for opportunistic mobile computing

Applications running on mobile terminals can benefit from exploiting transient connection opportunities: with an RTT of 2ms, even a 5s transient connection over a 50 Mbps 802.11a link represents 2500 RTTs and a chance to transfer up to 312.5 Mbytes. However, because of user mobility, such opportunistic time windows can be quite short. This paper investigates boosting CPU scheduling priorities of network-related processes on a mobile terminal to maximize benefit from communication opportunities. We explore the space of all possible boosting policies, propose two specific approaches, implement them in the Linux kernel, and study their performance. To our surprise, experimental results show that process reprioritization improves application performance only slightly, and only under heavy load. With today’s commodity hardware and commodity operating systems, both bulk transfer and interactive audio applications can be well-supported, under moderate loads, with no modifications.