Synchronous System and Perfect Failure Detector: Solvability and Efficiency Issue

We compare, in terms of solvability and efficiency, the synchronous model, noted SS, with the asynchronous model augmented with a perfect failure detector, noted SP . We first exhibit a problem that, although timefree, is solvable in SS but not in SP . We then examine whether one of these two models allows more efficient solutions for designing fault-tolerant applications. In particular, we concentrate on the uniform consensus problem which is solvable in both models, and we design a uniform consensus algorithm for the SS model that is more efficient than any algorithm solving uniform consensus in SP with respect to some significant time complexity measure. From a practical viewpoint, the synchronous model thus seems better than the asynchronous model augmented with a perfect