超立方体上路径算法的无死锁性

本文对超立方体上路径算法的无死锁性问题进行了研究，提出了超立方体上的两类最小无死锁受限条件，证明了路径算法的无死锁和对称性两者之间关系。     

星形图上无死锁的路径算法

星形图具有许多良好的拓扑性质，是一种有可能替代传统的超立方体的并行计算互联网络的模型。在本文中，作者针对在星形图这样一种高度规则的网络中，可能产生死锁的问题，对星形图上无死锁的路径算法进行了研究。首先利用星形图中匹配基的性质，给出了从Ｓｎ（Ｂ）到Ｓｋ的正规映射的定义，然后提出了星形图上的两个无死锁受限条件，最后证明了一个满足无死锁受限条件的路径算法。作者还提出了星形图上路径算法的最小无死锁受限条件     

基于2D Mesh的NoC路由算法设计与仿真

在研究Turn Model模型的基础上,提出一种基于2D Mesh结构的XY-YX路由算法,是一种确定性的无死锁的最短路径路由算法。给出无死锁的证明,通过片上网络（NoC）模拟仿真实验平台NIRGAM,将该算法在一个4×4的2D Mesh网络中进行仿真,并与XY路由算     

星形图上最小无死锁受限条件及无死锁路径算法

针对是形图中台能产生死锁的问题,对星形图上无无线锁的路径算法进行了研究,得到了星形图上的两类最小无死锁受限条件,并给出了一个满足该两类最小无死锁受限条件的无死锁路径算法。同时还证明了文献中提出的两个死锁受限条件分别只是该文所提出的两类最小无死锁受限条件的一个特例。     

双层二维网格结构间的Wromhole路由算法

二维网格结构由于其较好的可扩展性而被越来越广泛地应用，因此对于二维网格结构多处理机间的数据通信，寻找一个好的路由算法也越来越重要。以Intel公司的Option Red机器为背景，分析了双层二维网格结构多处理机间的通信机制，并且针对该实际结构，根据单层二维网格结构中以Wormhole原理为基础的Unicast自适应路由算法，提出了适用于双层二维网格结构的无死锁的Wormhole路由算法。根据该算法得出的数据传输路径是无死锁的最短传输路径。     

超立方体上基于缓冲机制的无死锁路径算法

本文研究了超立方体上基于单缓冲和双缓冲技术的无死锁受限条件，提出了相应的无死锁路径算法．性能分析表明，路径算法的效率和算法的自适应能力及算法的复杂性相关．     

Torus网络自适应容错路由算法

在应用于大规模并行计算机的互连网络的设计中,容错问题是其中的一个关键问题和难点问题。提出了一种基于Torus虫孔交换网络的容错路由算法,这一算法使用了矩形故障模型,无论故障区域大小多少和如何分布,算法始终是无死锁的,而且具有足够的自适应性,只要故障节点没有断开网络的连接,算法就能够通过选路使消息绕过故障区域,保持路由的连通性。同时,算法仅需要使用3个额外的虚拟通道。最后算法在不同故障率的Torus网络中进行了仿真实验,结果显示这一算法具有良好的平滑降级使用的特性。     

基于集束搜索和银行家算法的柔性制造系统无死锁调度

本文提出了一种基于启发式规则的无死锁调度算法,该算法基于集束搜索方法,局部评价函数和全局评价函数,在无缓冲区的情况下,采用单步前瞻的银行家算法来避免死锁。该算法可以迅速解决复杂制造系统的死锁和调度问题,折衷了计算时间的消耗和调度结果的质量。     

考虑缓冲区的自动生产单元的无死锁调度策略

在制造系统中,必须防止死锁的发生.本文提出了一种在制造系统(带有有限缓冲区)中搜索最优的无死锁调度的算法.为此首先介绍了死锁问题及其图论表示方法,然后在遗传算法的基础上,运用图论算法来保证无死锁的调度结果.为了保证遗传算法生成的调度策略能够满足所要求的约束,运用图论方法选择无死锁个体,或添加缓冲区,从而在基本保证了系统的主要性能指标的同时,得到系统可行的无死锁调度结果.最后给出了一个运用此方法解决死锁问题的实例.     

处理死锁的几种策略

在多道程序系统中，多个程序并发执行，共享系统资源，若对资源的管理和使用不当，会导致系统死锁。死锁避免是解决死锁问题的常用方法，而银行家算法是最著名的死锁避免算法。用类C语言描述了多项资源银行家算法。     

A necessary and sufficient condition for deadlock-free routing incut-through and store-and-forward networks

This paper develops the theoretical background for the design of deadlock-free adaptive routing algorithms for virtual cut-through and store-and-forward switching. This theory is valid for networks using either central buffers or edge buffers. Some basic definitions and three theorems are proposed, developing conditions to verify that an adaptive algorithm is deadlock-free, even when there are cyclic dependencies between routing resources. Moreover, we propose a necessary and sufficient condition for deadlock-free routing. Also, a design methodology is proposed. It supplies fully adaptive, minimal and non-minimal routing algorithms, guaranteeing that they are deadlock-free. The theory proposed in this paper extends the necessary and sufficient condition for wormhole switching previously proposed by us. The resulting routing algorithms are more flexible than the ones for wormhole switching. Also, the design methodology is much easier to apply because it automatically supplies deadlock-free routing algorithms     

A general methodology for direction-based irregular routing algorithms

This paper presents a general methodology for generating deadlock-free routing algorithms for irregular networks. Constructing a spanning tree on the given network, assigning directions to the network channels, creating deadlock-free zones, and specifying a logical sequence of the produced deadlock-free zones are the four fundamental steps that the proposed methodology takes to generate deadlock-free and connected routing algorithms. By applying the proposed methodology with two known labeling methods we have generated six irregular routing algorithms: three of them are novel routing algorithms and three of them (the Up/Down, Left/Right, and L-turn routing algorithms) have already been proposed in the literature. Extensive simulation experiments have been performed considering various network topologies, different network sizes (considering different network nodes and network channels), various message lengths, a variety of spanning tree roots, and a wide range of message (traffic) generation rates. Simulation results show that the six routing algorithms can be divided into three pairs. Routing members of each pair show similar behavior in terms of message latencies and saturation generation rates. However, it is worth noting that for a given topology the performance of the six routing algorithms may be totally different and it mainly depends on the network topology.     

Deadlock-free multicast wormhole routing in 2-D mesh multicomputers

Multicast communication services, in which the same message is delivered from a source node to an arbitrary number of destination nodes, are being provided in new-generation multicomputers. Broadcast is a special case of multicast in which a message is delivered to all nodes in the network. The nCUBE-2, a wormhole-routed hypercube multicomputer, provides hardware support for broadcast and a restricted form of multicast in which the destinations form a subcube. However, the broadcast routing algorithm adopted in the nCUBE-2 is not deadlock-free. In this paper, four multicast wormhole routing strategies for 2-D mesh multicomputers are proposed and studied. All of the algorithms are shown to be deadlock-free. These are the first deadlock-free multicast wormhole routing algorithms ever proposed. A simulation study has been conducted that compares the performance of these multicast algorithms under dynamic network traffic conditions in a 2-D mesh. The results indicate that a dual-path routing algorithm offers performance advantages over tree-based, multipath, and fixed-path algorithms     

A theory of deadlock-free adaptive multicast routing in wormholenetworks

A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network     

A necessary and sufficient condition for deadlock-free adaptiverouting in wormhole networks

Deadlock avoidance is a key issue in wormhole networks. A first approach by W.J. Dally and C.L. Seitz (1987) consists of removing the cyclic dependencies between channels. Many deterministic and adaptive routing algorithms have been proposed based on that approach. Although the absence of cyclic dependencies is a necessary and sufficient condition for deadlock-free deterministic routing, it is only a sufficient condition for deadlock-free adaptive routing. A more powerful approach by J. Duato (1991) only requires the absence of cyclic dependencies on a connected channel subset. The remaining channels can be used in almost any way. In this paper, we show that the previously mentioned approach is also a sufficient condition. Moreover, we propose a necessary and sufficient condition for deadlock-free adaptive routing. This condition is the key for the design of fully adaptive routing algorithms with minimum restrictions, An example shows the application of the new theory     

A new theory of deadlock-free adaptive routing in wormhole networks

The theoretical background for the design of deadlock-free adaptive routing algorithms for wormhole networks is developed. The author proposes some basic definitions and two theorems. These create the conditions to verify that an adaptive algorithm is deadlock-free, even when there are cycles in the channel dependency graph. Two design methodologies are also proposed. The first supplies algorithms with a high degree of freedom, without increasing the number of physical channels. The second methodology is intended for the design of fault-tolerant algorithms. Some examples are given to show the application of the methodologies. Simulations show the performance improvement that can be achieved by designing the routing algorithms with the new theory     

Deadlock-free adaptive routing in multicomputer networks usingvirtual channels

The use of adaptive routing in a multicomputer interconnection network improves network performance by using all available paths and provides fault tolerance by allowing messages to be routed around failed channels and nodes. Two deadlock-free adaptive routing algorithms are described. Both algorithms allocate virtual channels using a count of the number of dimension reversals a packet has performed to eliminate cycles in resource dependency graphs. The static algorithm eliminates cycles in the network channel dependency graph. The dynamic algorithm improves virtual channel utilization by permitting dependency cycles and instead eliminating cycles in the packet wait-for graph. It is proved that these algorithms are deadlock-free. Experimental measurements of their performance are presented     

不规则网络中基于拐弯模型的路由算法的设计

由虫孔路由交换器连接而成的不规则拓扑网络，越来越多地用于构建工作站机群系统（NOWs），以实现高性能价格比的并行处理．采用虫孔路由技术，网络中容易发生死锁．交换器之间连接的不规则性，使路由避免死锁问题变得更加复杂．本文给出了在不规则网络中，设计基于拐弯模型的无死锁路由算法的一般方法，并采用扩展链路方向的方法得到多种路由策略，确定了up-first与down-last两种性能较优的路由算法．最后通过模拟实验，评价了算法的性能．