Off-chip access localization for NoC-based multicores

In a network-on-chip based multicore, an off-chip data access needs to travel through the on-chip network, spending considerable amount of time within the chip (in addition to the memory access itself). Further, it also causes additional delays for on-chip accesses by creating contention on network resources. In this paper, we propose a compiler-guided off-chip data access localization strategy to ensure that, an off-chip access traverses a small number of links (hops) to reach the memory controller which governs the memory bank that holds the requested data. We present an extensive evaluation of this strategy using a set of 12 multithreaded application programs. The results collected clearly emphasize the importance of localizing off-chip accesses.