Comments, with reply, on "can redundancy and masking improve the performance of synchronizers?" by L. Kleeman and A. Cantoni

It is claimed in the above-mentioned work (ibid., vol.C-35, p.643-6, July 1986) that redundancy and masking techniques are ineffective in improving synchronizer performance due to metastable behavior. This claim is based on an input model that is not always valid, particularly in reliability analysis. The commenter points out the weakness in the assumed model and provides an alternative input model which can be used to analyze redundant synchronizer reliability. Based on the proposed alternative model it is shown that, under certain conditions, redundancy and masking can indeed improve synchronizer reliability. The authors reply that their original paper was the first to examine the question and naturally adopts the simplest modeling approach based on a deterministic model. They note that the differences in conclusion derive from the modeling assumptions for metastability, and asset that these need to be examined further by researchers. Some initial comments are given.<>