A New Token-Based Channel Access Protocol for Wavelength Division Multiplexed Multiprocessor Interconnects

Ha, Joon-Ho; Pinkston, Timothy M.

doi:10.1006/jpdc.1999.1599

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…Joshi et al [13] build a nanophotonics clos network, which provides uniform latency and throughput with low power. Ha et al [29] and Kodi et al [30] advocate token-based protocols to arbitrate for optical off-chip interconnects. An optical arbiter can be found in [31].…”

Section: Related Workmentioning

confidence: 99%

A Case for Handshake in Nanophotonic Interconnects

Wang

Jayabalan

Ahn

et al. 2013

2013 IEEE 27th International Symposium on Parallel and Distributed Processing

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Abstract-Nanophotonics has been proposed to design low latency and high bandwidth NOC for future Chip MultiProcessors (CMPs). Recent nanophotonic NOC designs adopt the token-based arbitration coupled with credit-based flow control, which leads to low bandwidth utilization. In this work, we propose two handshake schemes for nanophotonic interconnects in CMPs, Global Handshake (GHS) and Distributed Handshake (DHS), which get rid of the traditional creditbased flow control, reduce the average token waiting time, and finally improve the network throughput. Furthermore, we enhance the basic handshake schemes with setaside buffer and circulation techniques to overcome the Head-Of-Line (HOL) blocking. Our evaluation shows that the proposed handshake schemes improve network throughput by up to 62% under synthetic workloads. With the extracted trace traffic from real applications, the handshake schemes can reduce the communication delay by up to 59%. The basic handshake schemes add only 0.4% hardware overhead for optical components and negligible power consumption. In addition, the performance of the handshake schemes is independent of on-chip buffer space, which makes them feasible in a large scale nanophotonic interconnect design.

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Section: Related Workmentioning

confidence: 99%

A Case for Handshake in Nanophotonic Interconnects

Wang

Jayabalan

Ahn

et al. 2013

2013 IEEE 27th International Symposium on Parallel and Distributed Processing

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“…Time-division multiple access (TDMA) protocol is used as a control mechanism to achieve mutually exclusive access to the shared channel. Several TDMA protocols such as preallocation-based protocols, reservation-based protocols with preallocated reservation control, and token-based TDMA protocols have been reported [15], [17], [18]. In this paper, we consider an optical token-based TDMA protocol with preallocation to prevent collision of address requests.…”

Section: Architectural Overviewmentioning

confidence: 99%

Parallel optical interconnection network for SMPs

Louri

Kodi

2003

Frontiers in Optics

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The authors address the primary limitation of bandwidth demands for address transaction in future cache coherent symmetric multiprocessors (SMPs). As a solution, the authors propose a scalable address subnetwork called symmetric multiprocessor network (SYMNET) in which address requests and snoop responses of shared memory multiprocessors are implemented optically. As the address phase of the transaction is linked to the address bandwidth, which is the major bottleneck in SMPs, they focus only on the address subnetwork in this paper. SYMNET has the capability to pipeline address requests from successive processors, which results in increasing the available address bandwidth and lowering the latency of the network. An optical token is implemented to achieve mutual exclusion to the shared channel. This enables collisionless broadcast of multiple address requests. The simultaneous insertion of multiple address requests into the address subnetwork complicates cache coherence. A modified coherence protocol, called COSYM, was introduced to solve the coherence problem. The authors evaluated SYMNET with a subset of Splash-2 benchmarks running from 4-32 processors. Their simulation studies have shown 10%-67% improvement in execution time for various applications. It is also shown that the average latency for a transaction to complete using COSYM was 85% better than the electrical case. An overview of the proposed optical implementation of SYMNET is presented along with the theoretical power budget and bit-error rate analysis. This analysis shows that SYMNET can scale up to hundreds of processors while still using fast snoopy-based cache coherence protocols and that additional performance gains may be attained with further improvement in optical device technology.

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“…Time division multiple access (TDMA) protocol is used as a control mechanism to achieve mutual exclusive access to the transport part. Several TDMA protocols such as preallocation-based protocols, reservation-based protocols with preallocated reservation control, and token-based TDMA protocols have been reported [18], [16]. In this paper, we consider an optical token-based TDMA protocol with preallocation to prevent collision of address requests.…”

Section: Symnet: Address Subnetworkmentioning

confidence: 99%

“…U-bus extends the address bandwidth, but a new coherence protocol must be designed to maintain consistency across the caches. In the SPEED [16] architecture, write requests are broadcast using the snooping protocol and read requests are unicast using the directory protocol. The I-SPEED coherence protocol used for this architecture implements a single owner for dirty blocks to preserve the consistency of caches.…”

Section: Related Workmentioning

confidence: 99%

An optical interconnection network and a modified snooping protocol for the design of large-scale symmetric multiprocessors (SMPs)

Louri

Kodi

2004

IEEE Trans. Parallel Distrib. Syst.

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Abstract-In Symmetric Multiprocessors (SMPs), the cache coherence overhead and the speed of the shared buses limit the address/ snoop bandwidth needed to broadcast transactions to all processors. As a solution, a scalable address subnetwork called Symmetric Multiprocessor Network (SYMNET) is proposed in which address requests and snoop responses of SMPs are implemented optically. SYMNET not only uses passive optical interconnects that increases the speed of the proposed network, but also pipelines address requests at a much faster rate than electronics. This increases the address bandwidth for snooping, but the preservation of cache coherence can no longer be maintained with the usual snooping protocols. A modified coherence protocol, Coherence in SYMNET (COSYM), is introduced to solve the coherence problem. COSYM was evaluated with a subset of Splash-2 benchmarks and compared with the electrical bus-based MOESI protocol. The simulation studies have shown a 5-66 percent improvement in execution time for COSYM as compared to MOESI for various applications. Simulations have also shown that the average latency for a transaction to complete using COSYM protocol was 5-78 percent better than the MOESI protocol. It is also seen that SYMNET can scale up to hundreds of processors while still using fast snooping-based cache coherence protocols, and additional performance gains may be attained with further improvement in optical device technology.

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A New Token-Based Channel Access Protocol for Wavelength Division Multiplexed Multiprocessor Interconnects

Cited by 9 publications

References 19 publications

A Case for Handshake in Nanophotonic Interconnects

A Case for Handshake in Nanophotonic Interconnects

Parallel optical interconnection network for SMPs

An optical interconnection network and a modified snooping protocol for the design of large-scale symmetric multiprocessors (SMPs)

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