Pseudo-Circuit: Accelerating Communication for On-Chip Interconnection Networks

As the number of cores on a single chip increases with more recent technologies, a packet-switched on-chip interconnection network has become a de facto communication paradigm for chip multiprocessors (CMPs). However, it is inevitable to suffer from high communication latency due to the increasing number of hops. In this paper, we attempt to accelerate network communication by exploiting communication temporal locality with minimal additional hardware cost in the existing state-of-the-art router architecture. We observe that packets frequently traverse through the same path chosen by previous packets due to repeated communication patterns, such as frequent pair-wise communication. Motivated by our observation, we propose a pseudo-circuit scheme. With previous communication patterns, the scheme reserves crossbar connections creating pseudo-circuits, sharable partial circuits within a single router. It reuses the previous arbitration information to bypass switch arbitration if the next flit traverses through the same pseudo-circuit. To accelerate communication performance further, we also propose two aggressive schemes, pseudo-circuit speculation and buffer bypassing. Pseudo-circuit speculation creates more pseudo-circuits using unallocated crossbar connections while buffer bypassing skips buffer writes to eliminate one pipeline stage.