Abstract

We have defined and implemented a kernel API that makes every exported operation fully interruptible and restartable, thereby appearing atomic to the user. To achieve interruptibility, all possible kernel states in which a thread may become blocked for a "long" time are represented as kernel system calls, without requiring the kernel to retain any unexposable internal state. Since all kernel operations appear atomic, services such as transparent checkpointing and process migration that need access to the complete and consistent state of a process can be implemented by ordinary user-mode processes. Atomic operations also enable applications to provide reliability in a more straightforward manner. This API also allows us to explore novel kernel implementation techniques and to evaluate existing techniques. The Fluke kernel's single source implements either the "process" or the "interrupt" execution model on both uniprocessors and multiprocessors, depending on a configuration option affec...

Citations