Static Network Performance Research Articles

A Novel Tradeoff Analysis between Traffic Congestion and Packing Density of Interconnection Networks for Massively Parallel Computers

From disaster prevention to mitigation, drug analysis to drug design, agriculture to food security, IoT to AI, and big data analysis to knowledge or sentiment mining, a high computation power is a prime necessity at present. As such, massively parallel computer (MPC) systems comprising a large number of nodes are gaining popularity. To interconnect these huge numbers of nodes efficiently, hierarchical interconnection networks are an attractive and feasible option. A Tori-connected flattened butterfly network (TFBN) has been proposed by the authors in a prior work for future generation MPC systems. In the previous study, the static network performance and static cost-effectiveness were evaluated. In this research, a novel trade-off factor named message traffic congestion vs. packing density trade-off factor has been proposed, which characterizes the message congestion in the network and its packing density. The factor is used to statically assess the suitability of the implementation of an interconnection network. The message traffic density, packing density, and new factor have been evaluated for the proposed network and similar competitive networks such as TTN, TESH, 2D-Mesh, 3D-Mesh, 2D-Torus, and 3D-Torus. It has been found that the performance of the TFBN is superior to the other networks.

3D-TTN: a power efficient cost effective high performance hierarchical interconnection network for next generation green supercomputer.

Green computing is an important factor to ensure the eco-friendly use of computers and their resources. Electric power used in a computer converts into heat and thus, the system takes fewer watts ensuring less cooling. This lower energy consumption allows to be less costly to run as well as reduces the environmental impact of powering the computer. One of the most challenging problems for the modern green supercomputers is the reduction of current power consumptions. Consequently, regular conventional interconnection networks also show poor cost performance. On the other hand, hierarchical interconnection networks (like-3D-TTN) can be a possible solution to those issues. The main focus for this paper is the estimation of power usage at the on-chip level for 3D-TTN with the various other networks along with the analysis of static network performance. In our analysis, 3D-TTN requires about 32.48% less router power usage at the on-chip level and can also achieve near about 21% better diameter performance as well as 12% better average distance performance than the 5D-Torus network. Similarly, it also requires only about 14.43% higher router power usage; however, can achieve 23.21% better diameter performance and 26.3% better average distance than recent hierarchical interconnection network- 3D-TESH. The most attractive feature of this paper is the static hop distance parameter and per watt analysis (power-performance). According to our power-performance results, 3D-TTN can also show better result than the 3D-Mesh, 2D-Mesh, 2D-Torus and 3D-TESH network even at the lowest network level. Moreover, this paper is also featured with the static effectiveness analysis, which ensures cost and time efficiency of 3D-TTN.

Midimew Connected Torus Network for Next Generation Massively Parallel Computer System

Important scientific and engineering applications need high performance computing. This can be provided by massively parallel computer (MPC) systems. A sensitive step of maintaining such systems is the interconnection network used to interconnect the computing nodes. The topology used effects the network costs and performance significantly. Hierarchal interconnection networks (HIN) were introduced having several attractive features including low latency, low cost, and high fault tolerance. This paper proposes a new HIN called Midimew connect Torus Network (MTN) that provides constant node degree, high arc connectivity, high fault tolerance and a reasonable bisection width. Static network performance evaluation for the proposed MTN has been conducted and compared with other networks. The comparison included conventional topologies such as 2D Mesh and 2D Torus and hierarchal ones which are TESH and TTN. The comparison of result shows that with the cost of extra communication links MTN attains higher fault tolerance than that of TESH and mesh networks, and equal to that of TTN, and less than that of torus network. Also, the hierarchical networks such as MTN, TTN, and TESH yield moderate bisection width; and the bisection width of MTN is lower than that of mesh and torus networks. This paper shows the superiority of the proposed MTN by comparative study of static network performance.

The Static Performance Effect of Hybrid- Hierarchical Interconnection by Shifted Completely Connected Network

Massively parallel computer (MPC) systems execute many operations based on internal networks called interconnection networks. The performance of these networks is affected by their topologies.There are many topologies of interconnection networks for MPC systems, unfortunately, they faced many drawbacks. Expanding the size of the network degrades the performance of these topologies. That is why this current paper presents a hybrid-hierarchical interconnection network (HIN) topology by Shifted Completely Connected Network (SCCN) to circumvent the drawbacks of the existing topologies. An experimental evaluation involving the design and development of a hierarchical network was carried out. A two-dimensional higher level networks has been produced and its static network performance parameters evaluated through simulators. The finding of the simulations has shown some good performances compared to many previous designed networks. SCCN is better than all conventional networks in terms of diameter, cost and average distance.

TFBN: A Cost Effective High Performance Hierarchical Interconnection Network

In order to fulfill the increasing demand for computation power to process a boundless data concurrently within a very short time or real-time in many areas such as IoT, AI, machine learning, smart grid, and big data analytics, we need exa-scale or zetta-scale computation in the near future. Thus, to have this level of computation, we need a massively parallel computer (MPC) system that shall consist of millions of nodes; and, for the interconnection of these massive numbers of nodes, conventional topologies are infeasible. Thus, a hierarchical interconnection network (HIN) is a rational way to connect huge nodes. Through this article, we are proposing a new HIN, which is a tori-connected flattened butterfly network (TFBN) for the next generation MPC system. Numerous basic modules are hierarchically interconnected as a toroidal connection, whereby the basic modules are flattened butterfly networks. We have studied the network architecture, static network performance, and static cost-effectiveness of the proposed TFBN in detail; and compared static network and cost-effectiveness performance of the TFBN to those of TTN, torus, TESH, and mesh networks. It is depicted that TFBN possesses low diameter and average distance, high arc connectivity, and temperate bisection width. It also has better cost-effectiveness and cost-performance trade-off factor compared to those of TTN, torus, TESH, and mesh networks. The only shortcoming is that the complexity of wiring of the TFBN is higher than that of those networks; this is because the basic module necessitates some extra short length link to form the flattened butterfly network. Therefore, TFBN is a high performance and cost-effective HIN, and it will be a good option for the next generation MPC system.

HMMN: a cost-effective derivative of midimew-connected mesh network

A horizontal midimew-connected mesh network (HMMN) is constructed using multiple mesh-connected basic modules, whereby the basic modules are hierarchically interconnected by a horizontal midimew network for a higher level of hierarchy. In the HMMN, the vertical direction is toroidal connected and the horizontal direction is midimew links connected. This is why it is called HMMN. The architecture of the HMMN, the static network performance, and the dynamic communication performance were evaluated in our previous studies and were found to be good. However, the cost-effectiveness and cost-performance trade-off analysis of the HMMN have not been evaluated yet. Therefore, in this paper, we have evaluated packing density, message traffic density, cost-effective factor, time cost-effective factor, and static cost-performance trade-off factor of the proposed HMMN and compared these with those of mesh, torus, TESH, and MMN networks. Accordingly, the HMMN yields better results than the mesh, TESH, and MMN networks with respect to the above parameters. Even in regard to the extra cost of wrap-around links in all end-to-end nodes, the HMMN is more cost-effective than the torus network. However, this additional path between the end-to-end node using wrap-around links results in a low diameter, which in turn yields a slightly better density parameter and static cost-performance trade of factor for the torus network than for the HMMN.

A new power efficient high performance interconnection network for many-core processors

Next generation high performance computing will most likely depend on the massively parallel computers. The overall performance of a massively parallel computer system is heavily affected by the interconnection network and its processing nodes. Continuing advances in VLSI technologies promise to deliver more power to individual nodes. However, the on-chip interconnection networks consume up to 50% of the total chip power and off-chip bandwidth is limited to the maximum number of possible out going physical links. In addition, the long wiring and low performance of communication network overwhelm the benefit of parallel computer system whereas it increases total cost. In this paper, we propose a new interconnection network that reduces the problems of high power consumption, long wiring length and low bandwidth issues. We have measured the static network performance and required power consumption of our proposed ‘3D-TESH’ interconnection network and compared the performance with other networks at different levels of hierarchy such as inter-chips, inter-nodes and inter-cabinets. 3D-TESH network has achieved about 52.08% better diameter and about 45.71% better average distance than the 3D-Torus network with 12.61% less router power usage at on-chip level. Furthermore, 3D-TESH requires about 41% less router power usage than 5D-Torus at the on-chip level.

HTM: a new hierarchical interconnection network for future generation parallel computers

ABSTRACTIn this paper, we have discussed the architectural structure, static network performance, and dynamic communication performance of a new hierarchical interconnection network called hierarchical Tori connected mesh network (HTM). For the exploration of static network performance, we have evaluated degree, diameter, cost, average distance, arc-connectivity, bisection width, and wiring complexity. We have also evaluated the dynamic communication performance of HTM, its counter rival H3DM, and conventional mesh and torus networks using a deadlock-free dimension order routing using two virtual channels under uniform and non-uniform traffic patterns. The dynamic communication performance is evaluated using computer simulation. We discovered that the HTM has a number of lucrative properties. These include constant node degree, small diameter, low cost, small average distance, moderate (neither too low, nor too high) bisection width, and less wiring complexity. HTM also yields high throughput per link and very low zero load latency, which provide better dynamic communication performance than that of H3DM, mesh, and torus networks.

Zero-load predictive model for performance analysis in deflection routing NoCs

We study a static model for 2-D and 3-D networks that accurately represents the average distance travelled by packets under deflection routing, which is a specific form of adaptive routing. The model captures static properties of the network topology and the spatial distribution of traffic, but does not take into account traffic loading and congestion. Even though this static model cannot accurately predict packet latency under high load, we contend that it is a perfect predictor of deflection routing networks’ relative performance under any load condition below saturation, and thus always correctly predicts the optimum network configuration. This is verified through cycle-accurate simulations of congested and uncongested networks with fully adaptive, deflection routing for regular traffic patterns such as uniform random, localised, bursty, and others, as well as irregular patterns in both regular and irregular networks. As the networks with minimal average distance perform best even under high traffic load, the average distance model establishes a robust relation between a static network property, average distance, and network performance under load, providing new insight into network behaviour and an opportunity to identify the optimal network configuration without time-consuming simulations.

Uniform Traffic Patterns using Virtual Cut-Through Flow Control on VMMN

Abstract The previous study of static network performance of a Vertical Midimew connected Mesh Network (VMMN) was shown to be good. However, its dynamic communication performance has not been evaluated yet, we have proposed a deadlock free dimension order routing algorithm using 4 virtual channels. In this paper, The TOPAZ simulator is used to evaluate the dynamic communication performance of a VMMN with virtual cut-through flow control under uniform traffic pattern. We found that the VMMN dynamic communication performance is better than that of the hierarchical TESH network and its counter rival MMN.

Architecture and Network-on-Chip Implementation of a New Hierarchical Interconnection Network

A Midimew-connected Mesh Network (MMN) is a minimal distance mesh with wrap-around links network of multiple basic modules (BMs), in which the BMs are 2D-mesh networks that are hierarchically interconnected for higher-level networks. In this paper, we present the architecture of the MMN, addressing of node, routing of message, and evaluate the static network performance of MMN, TESH, mesh and torus networks. In addition, we propose the network-on-chip (NoC) implementation of MMN. With innovative combination of diagonal and hierarchical structure, the MMN possesses several attractive features, including constant degree, small diameter, low cost, small average distance, moderate bisection width and high fault tolerant performance than that of other conventional and hierarchical interconnection networks. The simple architecture of MMN is also highly suitable for NoC implementation. To implement all the links of level-3 MMN, only four layers are needed which is feasible with current and future VLSI technologies.

Reconfiguration and Yield of a Hierarchical Torus Network

This paper presents the reconfiguration and yield of a new interconnection network, Hierarchical Torus Network (HTN). An HTN is a 2D-torus network of multiple basic modules, in which the basic modules are 3D-torus networks that are hierarchically interconnected for higher level networks. The static network performance and dynamic communication performance under dimension-order routing of the HTN have already been studied and network performances are good. However, the fault tolerance performance of the HTN has not yet been evaluated. The goal of this paper is to derive a theoretical estimate of system yield for the HTN as a function of defect density with a reconfiguration approach by hardware redundancy. Yield is the probability of obtaining a fault-free network. Despite the dramatic improvement in fault tolerance in recent years, it is still necessary to provide redundancy and fault circumvention to achieve efficient system yield for large multicomputer systems. Thus, we provide redundant hardware to reconfigure the faulty nodes, switches, and links to healthy nodes, switches, and links. The results indicate that with a 25% redundancy the yield of the HTN is satisfactory. We also discuss the 3D-WSI implementation issue and show that HTN permits efficient VLSI/ULSI/WSI realization due to the fewer numbers of vertical links between the silicon wafers. The longest wire has a length of 4.5 cm, which represents 4.20 times improvement over the planar implementation.

High and stable performance under adverse traffic patterns of tori-connected torus network

A Tori-connected Torus Network (TTN) is a scalable network constructed from hierarchically-interconnected 2D-torus networks. Static network performance of fixed size TTN and dynamic communication performance under very common traffic patterns have been evaluated in our previous study. A generalized study of static network performance of TTN of any size and dynamic communication performance under adverse traffic patterns are the main focus of this paper. The TTN possesses several attractive features, including constant node degree, small diameter, low cost, small average distance, moderate bisection width, and better fault-tolerant performance than other networks. We compared with hierarchical TESH and MH3DT and conventional mesh and torus networks, and found that under adverse traffic patterns, the TTN yields high throughput and low latency, providing better dynamic communication performance compared to those networks. Also, the adverse traffic patterns have more stable throughput than uniform traffic in the TTN.

Interference aware power controlled forwarding for lifetime maximisation of wireless ad hoc networks

In a distributed control multi-hop wireless ad hoc network, multi-user interference plays a significant role in determining the network performance. Although the effects of hidden/exposed terminals on the system throughput in wireless ad hoc networks have been extensively studied, the multi-user interference power computation without as well as with distributed power control and their effects on the network level performance have not been analysed in the literature. In this study, via probabilistic analysis the authors capture the total interference power that a receiver node experiences for fixed power transmissions as well as variable power transmissions. The authors demonstrate the impact of interference on the effective communication range of the nodes. Subsequently, the authors study the joint impact of interference, power control, and different forwarding strategies on the network lifetime. They propose two variants of forwarding protocols, power controlled nearest forward (PCN) and network lifetime extending PCN (E-PCN), which are interference aware and offer network lifetime maximisation in power controlled transmission scenarios. The numerical results on random static network performance are verified by MATLAB as well as NS-2-based network simulations. The results show that the proposed protocols outperform the existing ones in terms of network lifetime.

Dynamic Communication Performance Enhancement in Hierarchical Torus Network by Selection Algorithm

A Hierarchical Torus Network (HTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 3D-torus networks that are hierarchically interconnected for higher-level networks. The static network performance of the HTN and its dynamic communication performance using the deterministic, dimension-order routing algorithm have already been evaluated and shown to be superior to the performance of other conventional and hierarchical interconnection networks. However, the assessment of the dynamic communication performance improvement of HTN by the efficient use of both the physical link and virtual channels has not yet been evaluated. This paper addresses three adaptive routing algorithms -- link-selection, channel-selection, and a combination of link-selection and channel-selection -- for the efficient use of physical links and virtual channels of an HTN to enhance dynamic communication performance. It also proves that the proposed adaptive routing algorithms are deadlock-free with 3 virtual channels. The dynamic communication performances of an HTN is evaluated by using dimension-order routing and proposed adaptive routing algorithms under various traffic patterns. It is found that the dynamic communication performance of an HTN using these adaptive routing algorithms are better than when the dimension-order routing is used, in terms of network throughput.

Symmetric and Folded Tori Connected Torus Network

Hierarchical interconnection networks provide high performance at low cost by exploring the locality that exists in the communication patterns of massively parallel computers. A Symmetric Tori connected Torus Network (STTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 2D-torus networks that are hierarchically interconnected for higher-level networks. We also fold the STTN to minimize the length of the longest wire of STTN. The folded network is called Folded Tori connected Torus Network (FTTN). In this paper, we present the architecture of the STTN and FTTN, addressing of node, routing of message, and evaluate the static network performance of STTN, FTTN, TTN, TESH, mesh, and torus networks. It is shown that both the STTN and FTTN possess several attractive features, including constant node degree, small diameter, low cost, small average distance, moderate bisection width, and high fault tolerant performance than that of other conventional and hierarchical interconnection networks. We further evaluate the longest wire length of FTTN and compare it with other networks. We found that the longest wire length of the FTTN is far lower than that of other networks considered in this paper while keeping good static network performance. It is just about (1 / 2 m th) of its rival STTN.

Routing performance enhancement in hierarchical torus network by link-selection algorithm

A hierarchical torus network (HTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 3D-torus networks that are hierarchically interconnected for higher-level networks. The static network performance of the HTN and its dynamic communication performance using the popular dimension-order routing algorithm have already been evaluated and shown to be superior to the performance of other conventional and hierarchical interconnection networks. In this paper, we propose a link-selection algorithm for efficient use of physical links of the HTN, while keeping the link-selection algorithm as simple as the dimension-order routing algorithm. We also prove that the proposed algorithm for the HTN is deadlock-free using three virtual channels. We evaluate the dynamic communication performance of an HTN using dimension-order routing and link-selection algorithms under various traffic patterns. We find that the dynamic communication performance of an HTN using the link-selection algorithm is better than when the dimension-order routing algorithm is used.