Efficient application migration under compiler guidance

摘要

Mobile computing based upon wireless technology as the interconnect and PDAs, Web-enabled cell phones etc. as the end devices provide a rich infrastructure for anywhere, anytime information access. Wireless connectivity also poses tough problems [11, 12]. Network nodes may be mobile and the connectivity could be sporadic. In many cases, application mobility involving migration from one network node to another could provide interesting possibilities. However, the migration process is expensive in terms of both time and power overheads. To minimize the migration cost, an efficient strategy must decide which parts of the program should migrate to continue execution and at which program point the migration should take place.In this work we develop a compiler framework to achieve the above two goals. First, the potential migration points are decided by analyzing the call chains in the code. Then the compiler determines what parts of the program are dead at these points. At run time, using the current context of the call chain, a decision on whether to migrate now or later is taken. Such a decision depends mainly upon the cost of migration involved at the current program point vs. at a later potential migration point. Our experiments with multimedia applications show that both the migration state and the latency are significantly reduced by our techniques over the base case of migration with full state in the absence of any compiler guidance. Thus, the key contribution of the paper is to provide an efficient migration methodology removing barriers to application mobility.