Automated Generation of Round-robin Arbitration and Crossbar Switch Logic
Shin, Eung Seo
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The objective of this thesis is to automate the design of round-robin arbiter logic. The resulting arbitration logic is more than 1.8X times faster than the fastest prior state-of-the-art arbitration logic the author could find reported in the literature. The generated arbiter implemented in a single chip is fast enough in 0.25ьm CMOS technology to achieve terabit switching with a single chip computer network switch. Moreover, this arbiter is applicable to crossbar (Xbar) arbitration logic. The generated Xbar, customized according to user specifications, provides multiple communication paths among masters and slaves. As the number of transistors on a single chip increases rapidly, there is a productivity gap between the number of transistors available in a chip and the number of transistors per hour a chip designer designs. One solution to reduce this productivity gap is to increase the use of Silicon Intellectual Property (SIP) cores. However, a SIP core should be customized before being used in a system different than the one for which it was designed. Thus, to reconfigure the SIP core, either an engineer must spend significant effort altering the core by hand or else an enhanced CAD tool can automatically customize the core according to customer specifications. In this thesis, we present SIP generator tools for arbiter and Xbar generation. First, we introduce a Round-robin Arbiter Generator (RAG). The RAG can generate a hierarchical Bus Arbiter (BA) which is faster than all known previous approaches. RAG can also generate a hierarchical Switch Arbiter (SA) which is faster than all known previous approaches. Using a 0.25ьm TSMC standard cell library from LEDA Systems, we show the arbitration time of a 32x32 SA and demonstrate that our SA meets the time constraint to achieve terabit throughput. Furthermore, using a novel token-passing hierarchical arbitration scheme, our 32x32 SA performs better than the Ping-Pong Arbiter and Programmable Priority Encoder by factors of 1.8X and 2.3X, respectively, with less power dissipation. Finally, we present an Xbar switch Generator (X-Gt) tool that automatically configures a crossbar for a multiprocessor System-on-a-Chip (SoC). An Xbar is generated in Register Transfer Level (RTL) Verilog HDL.