J. H. Kim and A. A. Chien. The impact of packetization in wormhole-routed networks. In Proceedings 5th ConferenceofParallel Architectures and Languages Europe, Munich (Germany),volume 694 of Lecture Notes in Computer Science, pages 242253. SpringerVerlag, 1993.  Home/Search   Document Details and Download   Summary   Related Articles   Check

.... Keywords: Wormhole routing, Analytical model 1 Introduction The concept of wormhole routing was rst described in a paper by Dally and Seitz [6] Since then a number of papers have been published addressing e.g. deadlock freedom, 9,28,10, 2, 14,21,5] eoeective utilization of bandwidth, see e.g. [19,13], and fault tolerance [20,12, 7, 15, 27, 11, 3] In recentyears the concept of wormhole routing has been taken up both in products and international standards, in particular in the domain of multiprocessing, see e.g. 22,25,24, 26, 16] The wormhole switching technique is basically an improvement ....

.... designed for hypercubes based on combinatorial arguments [18] Draper and Gosh uses elements of queuing theory to generate a method for k ary n cubes with wraparound channels that exhibits an impressive accuracy [8] Other approaches focus on particular load conditions such as bimodal load [19] or other routing techniques such as virtual cut through [1] All the models mentioned abovehaveweaknesses. Wehave mentioned that the model of Dally puts a limit on the number of other packets that eachpacket has to wait for. Other models, like that of Draper and Gosh, and that of Kim and Chien ....

J. H. Kim and A. A. Chien. The impact of packetization in wormhole-routed networks. In Proceedings 5th ConferenceofParallel Architectures and Languages Europe, Munich (Germany),volume 694 of Lecture Notes in Computer Science, pages 242253. SpringerVerlag, 1993.

....case in figure 2.6. A packet destined for b is blocked at the leftmost switch because the required link at the next step is held by a suspended packet destined for a . Throughput degradation follows from the fact that the subsequent links on the path towards b are not utilized. Packetization [86] reduces the effects of blocking to some extent. Otherwise, the challenge of the network designer is to find an appropriate routing scheme. In general, routing is a more critical design factor for wormhole switched networks than for buffered networks. Accordingly, a large number of algorithms have ....

....and thereby increased execution time. The increased hardness is due to the fine grained flow control scheme operating at the flit level. Hence, the gain of discrete event simulation is reduced. Usually, a straight forward simulation approach that traces each individual flit throughout the system [14, 32, 34, 39, 86, 118] is used. We recognize that the resulting samplepath is typically piecewise deterministic and propose a more efficient method. The point is that the number of state transitions in the underlying simulation model can be reduced by exploiting the nature of the sample path. The idea is to make ....

KIM, J., AND CHIEN, A. A. The impact of packetization in wormhole-routed networks. In Proceedings of the IFIP 11th World Computer Congress, Information Processing 89 (1993), pp. 228--241.

....12 packet up into several HIC packets. What we can hope for is that average latency will improve, and that the latency of packets gets an improved distribution, in the sense that there are fewer packets that deviates significantly from the average. The e#ect of such splits has been studied in [9], and the results for deterministic routing is that they actually makes average latency worse. The reason for this explained in our setting is that the latency of an SCI packet will at best equal the worst latency of each of the HIC packets. For networks with adaptive routing the results in [9] ....

....in [9] and the results for deterministic routing is that they actually makes average latency worse. The reason for this explained in our setting is that the latency of an SCI packet will at best equal the worst latency of each of the HIC packets. For networks with adaptive routing the results in [9] shows that packetization has barely any e#ect at all on latency. This can be explained by the fact that long delays caused by a long packets occupying links is avoided by the adaptivity of the routing scheme, and that because of that packetization aims at solving a non existent problem. With ....

J. H. Kim and A. A. Chien. The impact of packetization in wormholerouted networks. In Proceedings 5th Conference of Paral lel Architectures and Languages Europe, Munich (Germany), volume 694 of Lecture Notes in Computer Science, pages 242--253. Springer-Verlag, 1993.

....and router policies, the simulation studies focus on 64 byte packets traveling in an 8 Theta 8 square mesh using minimal path unicast routing algorithms. Because other studies have shown how tailoring network policies to different packet sizes can significantly improve application performance [10 12, 24], our experiments do not specifically address this issue. Instead, the simulations examine network per7 0.0000 0.0005 0.0010 0.0015 Applied load per node (packets cycle) 0.0 1000.0 2000.0 3000.0 Packet Switched Virtual Cut Through Wormhole 0.00000 0.00020 0.00040 0.00060 0.00080 Applied load per ....

J. H. Kim and A. A. Chien, "The impact of packetization in wormhole-routed networks," in Proc. Parallel Architectures and Languages, Europe, 1993.

....has not been fully explored. In [GN92a] Glass and Ni compared partially adaptive deadlock free routing schemes to dimension ordered schemes in mesh networks. In [LDT93] Liu et al. evaluated expected channel utilization for a class of deadlock free algorithms, again in mesh networks. Kim and Chien [KC93] assessed the effects of packetization on adaptive routing performance, Nowatzyk [Now89] has investigated a communication architecture using an adaptive algorithm, and recently Boppana and Chalasani [BC93] presented a comparative study of several deadlock free adaptive routing schemes. Almost all ....

J. H. Kim and A. A. Chien. The impact of packetization in wormhole-routed networks. In Proc. PARLE `93, pages 242--253, 1993.

....to eliminate much of the blocking, producing comparable or even superior performance to packetization. Together, all three techniques complement each other, providing robust performance over a variety of traffic mixes and message sizes. A preliminary version of some of this work appears in [31]. 1 Introduction In highly parallel machines, a collection of computing nodes works in concert to solve large application problems. The nodes communicate data and coordinate their efforts by sending and receiving messages through a routing network. Consequently, the achieved performance of such ....

J. H. Kim and A. A. Chien. The impact of packetization in wormhole-routed networks. In Proceedings of PARLE, June 1993.

....even in cases where all traffic is packetized, the correlation of traffic produced by the longer messages can be an important performance factor. We believe that bimodal distributions of message sizes are a realistic model of traffic. Some experiments with bimodal traffic can be found in [9, 10, 12]. Natural Workloads such as captured message traffic (traces) or even actual message traffic (emulation) are the most realistic source of communication workloads. Studies such as [7, 4] have produced application level traces and communication traffic characterization which can be used to drive ....

J. H. Kim and A. A. Chien. The impact of packetization in wormhole-routed networks. In Proceedings of PARLE, June 1993.

....amount of short and long messages. This is an interesting issue but beyond the scope of this dissertation, so it is not discussed further. Our previous work covers in detail the related issues, including the impact of packet interleaving on the average latency of messages with different sizes [96, 112, 113]. 6.3.4 Integrated services with CBR VBR ABR traffic Many existing networks and most networks in the near future need to support a wide range of applications which will require different traffic characteristics and communication services. We evaluate how effectively networks with different ....

J. H. Kim and A. A. Chien. "The impact of packetization in wormhole-routed networks, " in Proceedings of PARLE, Munich, Germany, June 1993, pp. 242--253.

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