Grid Checkpointing: an Innovative Rollback Support for Speculative Simulation

Abstract

We present a new technique for application-transparent incremental checkpointing in speculative simulation, referred to as {\em Grid Checkpointing}. With our proposal, we fully separate the interception of memory update operations from memory-map management. This enables tracing memory updates that occur in the state of a simulation object via an extremely limited set of instrumentation instructions. At the methodological level, our proposal exploits an overlaid grid layout on the memory area used to host the chunks of an object state, and manages concise data for enabling incremental checkpointing with no need for knowing which chunks are really allocated/updated into the object state. Additionally, grid checkpointing fully avoids logging the addresses of the touched memory zones, as instead takes place in other existing proposals. We embedded our solution into the PARSIR (PARallel SImulation Runner) open source package and report the results of an experimental study that compares grid checkpointing with other solutions available in the literature. The results demonstrate that our approach enables incremental checkpointing via memory update tracing with nearly negligible runtime cost.