Conflict-free vector access using a dynamic storage scheme

Abstract

An approach whereby conflict-free access of any constant stride can be made by selecting a storage scheme for each vector based on the accessing patterns used with that vector is considered. By factoring the stride into two components, one a power of 2 and the other relatively prime to 2, a storage scheme that allows conflict-free access to the vector using the specified stride can be synthesized. All such schemes are based on a variation of the row rotation mechanism proposed by P. Budnik and D. Kuck (ibid., vol.C-20. no.12, pp.1566-9, Dec. 1971). Each storage scheme is based on two parameters, one describing the type of rotation to perform and the other describing the amount of memory to be rotated as a single block. The performance of the memory under access strides other than the stride used to specify the storage scheme is also considered. Modeling these other strides represents a vector being accessed with multiple strides as well as situations when the stride cannot be determined prior to initializing the vector. Simulation results show that if a single buffer is added to each memory port, then the average performance of the dynamic scheme surpasses that of the interleaved scheme for arbitrary stride accesses. >