Efficient Resource Sharing in Concurrent Error Detecting Superscalar Microarchitectures

Tuesday November 30, 2004
Hamerschlag Hall D-210
4:00 pm

This is a practice talk for the upcoming IEEE Micro conference, December 4-8.

Jared Smolens
Carnegie Mellon University

Previous proposals for soft-error tolerance have called for redundantly executing a program as two concurrent threads on a superscalar microarchitecture. In a balanced superscalar design, the extra workload from redundant execution induces a severe performance penalty due to increased contention for resources throughout the datapath. This paper identifies and analyzes four key factors that affect the performance of redundant execution, namely 1) issue bandwidth and functional unit contention, 2) issue queue and reorder buffer capacity contention, 3) decode and retirement bandwidth contention, and 4) coupling between redundant threads' dynamic resource requirements. Based on this analysis, we propose the SHREC microarchitecture for asymmetric and staggered redundant execution. This microarchitecture addresses the four factors in an integrated design without requiring prohibitive additional hardware resources. In comparison to conventional single-threaded execution on a state-ofthe-art superscalar microarchitecture with comparable cost, SHREC reduces the average performance penalty to within 4% on integer and 15% on floating-point SPEC2K benchmarks by sharing resources more efficiently between the redundant threads.

Jared Smolens is a third year PhD student in the Computer Architecture Laboratory at Carnegie Mellon, where he is advised by Prof. James Hoe. His time is primarily devoted to the TRUSS project. His research interests include multiprocessor and microprocessor architecture, fault tolerance, and performance modeling.