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Reduction in synchronisation in bundled data systems. Charlie Brej APT Group Manchester University. Outline. Asynchronous Circuits Early Output Counterflow Networks Anti-Tokens Conclusions. Asynchronous Latch. Ri. Ro. Latch. Ai. Ao. Req. Ack. Asynchronous Pipeline.
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Reduction in synchronisation in bundled data systems Charlie Brej APT Group Manchester University ToBaCo '04
Outline • Asynchronous Circuits • Early Output • Counterflow Networks • Anti-Tokens • Conclusions ToBaCo '04
Asynchronous Latch Ri Ro Latch Ai Ao Req Ack ToBaCo '04
Asynchronous Pipeline ToBaCo '04
Pipeline merging ToBaCo '04
Pipeline merging C ToBaCo '04
Pipeline merging C 0 0 1 ToBaCo '04
Early Output cases Average:80% ToBaCo '04
Early Output Go! 0 0 ? ToBaCo '04
Guarding Problem: • Inputs • Late • Unnecessary • Acknowledge before ready Solution: • Validity signal (Vo) Ri Ro Vo Latch Ao Ai ToBaCo '04
Early Output with Guarding Go! 0 0 C 1 ToBaCo '04
Counterflow Networks • Nodes fire when a threshold of neighbors have fired • No Inputs/Outputs, just Links • Neural network like operation ToBaCo '04
Counterflow Networks ToBaCo '04
Counterflow Networks ToBaCo '04
Counterflow Networks ToBaCo '04
Counterflow Networks ToBaCo '04
Anti-Tokens • Reproduce the counterflow network behavior in the single-rail system. • Inputs allow early acknowledgements • Output latches can acknowledge early • Propagate early acknowledgements ToBaCo '04
Anti-Token Generation Go! 0 0 C A ToBaCo '04
Anti-Token Propagation Go! A A C A ToBaCo '04
Token Pass T T T ToBaCo '04
Anti-Token Pass A A A ToBaCo '04
Token Anti-Token collision T ? A ToBaCo '04
Token Anti-Token collision 2 T T A ToBaCo '04
Dual-Purpose Signals • Arbiter free • Req: • Token Request • Acknowledge Anti-Token • Ack: • Request Anti-Token • Acknowledge Token Req Ack ToBaCo '04
Standard ToBaCo '04
Standard ToBaCo '04
Early Output ToBaCo '04
Anti-Tokens ToBaCo '04
Anti-Tokens ToBaCo '04
Conclusions • Early output easy on most blocks • Multiplexers • Bit-level pipelining • Counterflow • no arbitration • Increased performance • Mixed use of techniques • Fewer synchronisations ToBaCo '04