Low-Overhead Network-on-Chip Support for Location-Oblivious Task Placement
Venue
IEEE Transactions on Computers, vol. Volume 63, Issue 6 (2014), pp. 1487 - 1500
Publication Year
2014
Authors
Gwangsun Kim, Lee, M.M.-J., John Kim, Dennis Abts, Michael R. Marty
BibTeX
Abstract
Many-core processors will have many processing cores with a network-on-chip (NoC)
that provides access to shared resources such as main memory and on-chip caches.
However, locally-fair arbitration in multi-stage NoC can lead to globally unfair
access to shared resources and impact system-level performance depending on where
each task is physically placed. In this work, we propose an arbitration to provide
equality-of-service (EoS) in the network and provide support for location-oblivious
task placement. We propose using probabilistic arbitration combined with
distance-based weights to achieve EoS and overcome the limitation of round-robin
arbiter. However, the complexity of probabilistic arbitration results in high area
and long latency which negatively impacts performance. In order to reduce the
hardware complexity, we propose an hybrid arbiter that switches between a simple
arbiter at low load and a complex arbiter at high load. The hybrid arbiter is
enabled by the observation that arbitration only impacts the overall performance
and global fairness at a high load. We evaluate our arbitration scheme with
synthetic traffic patterns and GPGPU benchmarks. Our results shows that hybrid
arbiter that combines round-robin arbiter with probabilistic distance-based
arbitration reduces performance variation as task placement is varied and also
improves average IPC.
