Enabling autonomic behavior in systems software with hot swapping

Autonomic computing systems are designed to be self-diagnosing and self-healing, such that they detect performance and correctness problems, identify their causes, and apply the appropriate remedy. These abilities can improve performance, uptime, and security, while simultaneously reducing the effort and skills required of system administrators. One way that systems can support these abilities is by allowing monitoring code, diagnostic code, and function implementations to be dynamically inserted and removed in live systems. This “hot swapping” avoids the requisite prescience and additional complexity inherent in creating systems that have all possible configurations built in ahead of time. For already-complex pieces of code such as operating systems, hot swapping provides a simpler, higher performance, and more maintainable method of achieving autonomic behavior. In this paper we discuss hot swapping as a technique for enabling autonomic computing in systems software. First we discuss its advantages and describe the required system structure. Then, for experimental K42 operating system which explicitly supports interposition and replacement of active operating system code, we describe its infrastructure for hot swapping and several instances of its use demonstrating autonomic behavior.