Fair Access to External Memory for Chip-multiprocessor

Abstract

A memory arbitration scheme is required for chip-multiprocessor accessing external (off-chip) memory. A round-robin arbitration is an efficient and low-cost candidate for chip-multiprocessor. However, the adoption of simple round robin scheme raises a potential problem of uneven sharing of external memory bandwidth. One way to manage an unbalanced resource allocation resulting from the use of arbiters is to use priority arbitrations combined with a look-up table, but this is not economical since large lookup tables require a large silicon area. We propose an admission control scheme operating at the edge of on-chip interconnection. The fair-sharing service is guaranteed using a token mechanism to schedule packets onto fabric. This work shows that a fair service problem can be solved by controlling traffic of on-chip interconnect, since it avoid saturation in critical paths and to maintain equilibrium in the allocation of resource.