Citation
Natalie Enright Jerger, Li-Shiuan Peh, Mikko Lipasti. "Circuit-Switched Coherence". Network on Chip Symposium, April, 2008.

Abstract
Our characterization of a suite of commercial and scientific workloads on a 16-core cache-coherent chip multiprocessor (CMP) shows that overall system performance is sensitive to on-chip communication latency, and can degrade by 20% or more due to long interconnect latencies. On the other hand, communication bandwidth demand is low. These results prompt us to explore circuit-switched networks. Circuit-switched networks can significantly lower the communication latency between processor cores, when compared to packet-switched networks, since once circuits are set up, communication latency approaches pure interconnect delay. However, if circuits are not frequently reused, the long setup time can hurt overall performance, as is demonstrated by th e poor performance of traditional circuit-switched networks -- all applications saw a slowdown rather than a speedup with a traditional circuit-switched network. To combat this problem, we propose hybrid circuit switching (HCS), a network design which removes the circuit setup time overhead by intermingling packet-switched flits with circuit-switched flits. Additionally, we co-design a prediction-based coherence protocol that leverages the existence of circuits to optimize pair-wise sharing between cores. The protocol allows pair-wise sharers to communicate directly with each other via circuits and drives up circuit reuse. Circuit-switched coherence provides up to 23% savings in network latency which leads to an overall system performance improvement of up to 15%. In short, we show HCS delivering the latency benefits of circuit switching, while sustaining the throughput benefits of packet switching, in a design realizable with low area and power overhead.

Electronic downloads

• EnrightJergerN-CircuitSwitchedCoherence.pdf · application/pdf · 640 kbytes

Citation formats

• HTML

  Natalie Enright Jerger, Li-Shiuan Peh, Mikko Lipasti. <a
  href="http://www.gigascale.org/pubs/1296.html">Circuit-Switched
  Coherence</a>, Network on Chip Symposium, April, 2008.

• Plain text

  Natalie Enright Jerger, Li-Shiuan Peh, Mikko Lipasti.
  "Circuit-Switched Coherence". Network on Chip Symposium,
  April, 2008.

• BibTeX

  @inproceedings{Enright JergerPehLipasti2008,
      author = {Natalie Enright Jerger and Li-Shiuan Peh and Mikko
                Lipasti},
      title = {Circuit-Switched Coherence},
      booktitle = {Network on Chip Symposium},
      month = {April},
      year = {2008},
      URL = {http://www.gigascale.org/pubs/1296.html}
  }
  

Posted by Natalie Enright Jerger on 1 May 2008..

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