CUHK electronic theses & dissertations collection

Integrating many processing elements (PE) in a single chip is inevitable as silicon technology allows more than one billion of transistors in a single piece of silicon. Networks-on-Chip (NoCs) has been proposed as a scalable solution to both increasing bandwidth requirements and physical design problems for multi-PE chips. However, as multi-PE chips drive the design focus to shift from the computation-centric to communication-centric, area and power costs consumed by communication has become comparable to what computation consumes.The second direction is to reduce hop counts of packets when they travel from sources to destinations, and thus to reduce power consumption of NoCs. The reduction of hop counts is realized by using a recently proposed express virtual channel (EVC) technique to virtually bypass intermediate routers. We study the EVC technique in two domains. The first domain is to present a high-level, application-specific methodology to improve power efficiency of EVC paths early in the design stage. The methodology includes three steps. Firstly, aggregate communication loads between routers are calculated. Secondly, an energy reduction model and an energy overhead model are developed. Finally, energy savings of all possible EVCs path are calculated and a greedy algorithm is applied to insert EVCs paths in an iterative way.The second domain is to exploit the EVC flow control in design and implementation of low-power NoCs. We firstly present cost-efficient hardware components for both EVC source and EVC bypass routers, then propose a statistical approach to customize buffer architectures for EVC networks, then describe creative use of low-power circuit techniques such as clock gating and operand isolation for EVC routers, and finally evaluate EVC NoCs through detailed ASIC implementations. Results show that EVC NoCs can save up to 34.26% of power compared to baseline NoCs.This thesis tackles design and implementation of cost-efficient NoCs along two orthogonal directions. The first direction is to reduce area and power costs of a single virtual channel router. Through ASIC implementations, we find that allocator logic, including both virtual channel allocator (VA) and switch allocator (SA), consumes a large amount of costs. Based on RTL simulations for the entire NoCs, we identify great opportunities to reduce design costs of VA and then propose two low-complexity allocators: look-ahead VA and combined switch-VC allocator (SVA). Evaluations are performed for a wide range of traffic patterns and router parameters. Results show that both proposed architectures significantly reduce area and power costs of allocators without penalties on network performances.Zhang, Min.Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: .Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.Includes bibliographical references (leaves 139-145).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstract also in Chinese