QSwitch: Dynamical Off-Chip Bandwidth Allocation Between Local and Remote Accesses

Abstract

Multisocket computer systems are popular in workstations and servers. However, they suffer from the relatively low bandwidth of intersocket communication especially for massive parallel workloads that generate many intersocket requests for synchronizations and remote memory accesses. Intersocket traffic puts pressure on the underlying network connecting all processors with a limited bandwidth confined by pin resources. Given this constraint, we propose to dynamically increase the intersocket bandwidth by sacrificing off-chip memory bandwidth when systems have heavy intersocket communication but few off-chip memory accesses. Our design increases the physical bandwidth for intersocket communication via switching the function of pins from off-chip memory accesses to intersocket communication and can achieve an average performance speedup of 1.28 in geocentric mean for selected parallel multithreaded benchmarks.