Approximating Age-Based Arbitration in On-Chip Networks [abstract] (ACM DL, PDF)
Michael M. Lee, John Kim, Dennis Abts, Michael Marty, and Jae W. Lee
Proceedings of the 19th International Conference on Parallel Architectures and Compilation Techniques (PACT), September 2010.
The on-chip network of emerging many-core CMPs enables the sharing of
numerous on-chip components. This on-chip network needs to ensure
fairness when accessing the shared resources. In this work, we propose
providing equality of service (EoS) in future many-core CMPs on-chip
networks by leveraging distance, or hop count, to approximate the age
of packets in the network. We propose probabilistic arbitration
combined with distance-based weights to achieve EoS and overcome the
limitation of conventional round-robin arbiter. We describe how
nonlinear weights need to be used with probabilistic arbiters and
propose three different arbitration weight metrics - fixed weight,
constantly increasing weight, and variably increasing weight. By only
modifying the arbitration of an on-chip router, we do not require
any additional buffers or virtual channels and create a
complexity-effective mechanism for achieving EoS.