Using Peer Support to Reduce Fault-Tolerant Overhead in Distributed Shared Memories

We present a peer logging system for reducing performance overhead in fault-tolerant distributed shared memory systems. Our system provides fault-tolerant shared memory using individual checkpointing and rollback. Peer logging logs DSM modification messages to remote nodes instead of to local disks. We present results for implementations of our fault-tolerant technique using simulations of both TreadMarks, a software-only DSM, and Cashmere, a DSM using memory mapped hardware. We compare simulations with no fault tolerance to simulations with local disk logging and peer logging. We present results showing that fault-tolerant Treadmarks can be achieved with an average of 17% overhead for peer logging. We also present results showing that while almost any DSM protocol can be made fault tolerant, systems with localized DSM page meta-data have much lower overheads.