A Comparative Analysis of Deadlock Recovery and

Avoidance-Based Routing Algorithms in Wormhole-Switched k-Ary n-Cubes

Paper review Paper review Reviewer Reviewer ：： Nthu CS03 kwcNthu CS03 kwc

OutlineOutline

IntroductionIntroduction MotivationMotivation Simulation model Simulation model Performance evaluationPerformance evaluation

ComparisonComparison Previous workPrevious work SimulationSimulation ConclusionConclusion

My commentMy comment

IntroductionIntroduction

MotivationMotivation ：： Before routing schemes can be

successfully incorporated in future practical multicomputers, it is necessary to develop a clear understanding of the factors, which affects their potential performance.

IntroductionIntroduction （（ cont.cont. ）） Comparison modelComparison model：：

Message destinations are uniformly distributed across the network nodes.

Nodes generate traffic independently of each other, and which follows a Poisson process with a mean rate of λg messages/cycle.

Message length is fixed and equal to M flits, each of which requires one-cycle transmission time across a physical channels.

The local queue in the source node has infinite capacity. Moreover, messages are transferred to the local PE through the ejection channel as soon as they arrive at their destinations.

V virtual channels are used per physical channel. K-ary n-cubes.K-ary n-cubes.

IntroductionIntroduction （（ cont.cont. ）） Performance evaluationPerformance evaluation

Message latencyMessage latency The time required by a message to cross

from source to destination. Traffic saturation rateTraffic saturation rate

The traffic generation rate when network The traffic generation rate when network enters the saturation region.enters the saturation region.

ComparisonComparison

Previous workPrevious work ““Performance comparison of deadlock Performance comparison of deadlock

recovery and deadlock avoidance recovery and deadlock avoidance routing algorithms in wormhole-routing algorithms in wormhole-switched networks” switched networks” in IEE Proceedings-in IEE Proceedings-Computers and Digital Techniques, Vol. Computers and Digital Techniques, Vol. 150, No. 2, pp. 97-106, 2003.150, No. 2, pp. 97-106, 2003.

Simulation ComparisonSimulation Comparison

Simulation Algorithm used in these worksSimulation Algorithm used in these works ：：

Previous work Current work

Deadlock Recovery：Compressionless Routing

Deadlock Recovery：Compressionless RoutingSoftware-Based RoutingDisha Routing

Deadlock Avoidance：Duato’s Adaptive Routing

Deadlock Avoidance：Duato’s Adaptive Routing

Test-Bed：Deterministic Routing

Test-Bed：none

Simulation ComparisonSimulation ComparisonCurrent workCurrent work Previous workPrevious work

Simulation Comparison Simulation Comparison (cont.)(cont.)

Current workCurrent work Previous workPrevious work

Simulation ComparisonSimulation ComparisonCurrent workCurrent work Previous workPrevious work

Simulation ComparisonSimulation ComparisonCurrent workCurrent work Previous workPrevious work

ConclusionConclusion The digest of conclusion is list as followsThe digest of conclusion is list as follows ：：

Networks with a small diameter compressionless routing Networks with a small diameter compressionless routing outperforms both deterministic and Duato’s adaptive outperforms both deterministic and Duato’s adaptive routing, especially when a few number of virtual routing, especially when a few number of virtual channels per physical channels are used.channels per physical channels are used.

Either he network size or the number of virtual channels Either he network size or the number of virtual channels increases the performance advantages of increases the performance advantages of compressionless routing diminish.compressionless routing diminish.

Throughput of wormhole-switched k-ary n-cubes is highly Throughput of wormhole-switched k-ary n-cubes is highly sensitive to the congestion channel in the source node.sensitive to the congestion channel in the source node.

The high degree of adaptivity offered by a particular The high degree of adaptivity offered by a particular instance of k-ary n-cubes, notably the hypercube, enables instance of k-ary n-cubes, notably the hypercube, enables Duato’s adaptive routing to better performance Duato’s adaptive routing to better performance characteristics than compressionless routing when a characteristics than compressionless routing when a moderate number of virtual channels are used.moderate number of virtual channels are used.

My CommentMy Comment

Conclusions in current work are Conclusions in current work are overlapped or can be conducted by overlapped or can be conducted by previous work.previous work. （（ Section of conclusion Section of conclusion in both papers are almost the same.in both papers are almost the same.））

Current work is a refined report of Current work is a refined report of previous work. But the topic previous work. But the topic overlapping and lacking originality overlapping and lacking originality makes me feel that it should be done in makes me feel that it should be done in previous work, not in another analysis previous work, not in another analysis report.report.