Tracing of User Programs for Incremental Replay

User programs may be long-running and have arbitrarily complex interactions with their environment, and thus reproducing bugs by repeated re-execution may be impractical or impossible. To facilitate the debugging process, we hope to produce a tool which allows the user to eeciently trace the execution of a given program, and then exactly replay any interval of the traced execution. In this paper we show how the technique of tracing unique-spanning reads can be further reened to eeciently trace system calls during program execution using a new state machine to detect and trace reads following system calls. We also discuss how interrupts can be traced, and how the trace information can be used to incrementally replay a program execution, including system calls executed by the program and interrupts which occurred during the original execution.