General broadcasting algorithms in one-port wormhole routed hypercubes

Wormhole routing has been accepted as an efficient switching mechanism in point-to-point interconnection networks. Here the network resource, i.e. node buffers and communication channels, are effectively utilized to deliver message across the network; We consider the problem of broadcasting a message in the hypercue equipped with the wormhole switching mechanism. The model is a generalization of an earlier work and considers a broadcast path-length of {dollar}m\ (1\leq m\leq n{dollar}) in the n-cube with a single-port communication capability. In this thesis, the scheme of e-cube and a Gray code path routing and intermediate reception capability have been adopted in order to solve the problem of broadcasting in one-port wormhole routed hypercubes. Two methods have been suggested; one is based on utilizing the Gray codes (Gray code path-based routing), while the other is based on the recursive partitioning of the cube (cube-based routing). The number of routing steps in both methods are compared to those in the previous results, as well as to the lower bounds derived based on the path-length m assumption. A cube-based and a path-based algorithm give {dollar}T(R)+(k\sb{c}+1)T(m){dollar} and {dollar}k\sb{G} +T(m){dollar} routing steps, respectively. By comparison with routing steps of both algorithms, the performance of the path-based algorithm shows better than that of the cube-based; The results of this work are significant and can be used for immediate implementation in contemporary machines most of which are equipped with wormhole routing and serial communication capability

Routing in Mobius Cubes

Möbius cube je zajímavou topologií, která vznikla z topologie hypercube. Největší výhoda oproti hypercube je v přibližně polovičním průměru Möbius cube. V této práci je popsán algoritmus nejkratšího routování a jsou popsány i jeho klady a zápory. Velkou nevýhodou je možnost pádu do stavu uzamknutí (deadlock). Proto je v práci představen nový deadlock-free algoritmus a porovnán s předchozím algoritmem. Dále je v práci popsána možnost použití hypercubického multicast 1-portového wormhole algoritmu na Möbius cube.The Möbius cube is an interesting topology created from the hypercube. Its main advantage is the which that is around one half of the diameter of the hypercube. In this thesis, the shortest path algorithm is described as well as its properties and drawbacks. One major drawback is the possibility of a deadlock. Therefore, a new deadlock-free routing algorithm is introduced and compared to the previous algorithm. Later, usage of hypercube's multicast 1-port wormhole algorithm on the Möbius cube is described

Analysis of wormhole routings in cayley graphs of permutation groups.

Over a decade, a new class of switching technology, called wormhole routing, has been investigated in the multicomputer interconnection network field. Several classes of wormhole routing algorithms have been proposed. Most of the algorithms have been centered on the traditional binary hypercube, k-ary n-cube mesh, and torus networks. In the design of a wormhole routing algorithm, deadlock avoidance scheme is the main concern. Recently, new classes of networks called Cayley graphs of permutation groups are considered very promising alternatives. Although proposed Cayley networks have superior topological properties over the traditional network topologies, the design of the deadlock-free wormhole routing algorithm in these networks is not simple. In this dissertation, we investigate deadlock free wormhole routing algorithms in the several classes of Cayley networks, such as complete-transposition and star networks. We evaluate several classes of routing algorithms on these networks, and compare the performance of each algorithm to the simulation study. Also, the performances of these networks are compared to the traditional networks. Through extensive simulation we found that adaptive algorithm outperformed deterministic algorithm in general with more virtual channels. On the network performance comparison, the complete transposition network showed the best performance among the similar sized networks, and the binary hypercube performed better compared to the star graph

New Fault Tolerant Multicast Routing Techniques to Enhance Distributed-Memory Systems Performance

Distributed-memory systems are a key to achieve high performance computing and the most favorable architectures used in advanced research problems. Mesh connected multicomputer are one of the most popular architectures that have been implemented in many distributed-memory systems. These systems must support communication operations efficiently to achieve good performance. The wormhole switching technique has been widely used in design of distributed-memory systems in which the packet is divided into small flits. Also, the multicast communication has been widely used in distributed-memory systems which is one source node sends the same message to several destination nodes. Fault tolerance refers to the ability of the system to operate correctly in the presence of faults. Development of fault tolerant multicast routing algorithms in 2D mesh networks is an important issue. This dissertation presents, new fault tolerant multicast routing algorithms for distributed-memory systems performance using wormhole routed 2D mesh. These algorithms are described for fault tolerant routing in 2D mesh networks, but it can also be extended to other topologies. These algorithms are a combination of a unicast-based multicast algorithm and tree-based multicast algorithms. These algorithms works effectively for the most commonly encountered faults in mesh networks, f-rings, f-chains and concave fault regions. It is shown that the proposed routing algorithms are effective even in the presence of a large number of fault regions and large size of fault region. These algorithms are proved to be deadlock-free. Also, the problem of fault regions overlap is solved. Four essential performance metrics in mesh networks will be considered and calculated; also these algorithms are a limited-global-information-based multicasting which is a compromise of local-information-based approach and global-information-based approach. Data mining is used to validate the results and to enlarge the sample. The proposed new multicast routing techniques are used to enhance the performance of distributed-memory systems. Simulation results are presented to demonstrate the efficiency of the proposed algorithms

Communication algorithms for isotropic tasks in hypercubes and wraparound meshes

Cover title.Includes bibliographical references (p. 29-30).Research supported by the NSF. NSF-ECS-8519058 Research supported by the ARO. DAAL03-86-K-0171by Emmanouel A. Varvarigos and Dimitri P. Bertsekas

A testbed for embedded systems

Testing and Debugging are often the most difficult phase of software development. This is especially true of embedded systems which are usually concurrent, have real-time performance and correctness constraints and which execute in the field in an environment which may not permit internal scrutiny of the software behaviour. Although good software engineering practices help, they will never eliminate the need for testing and debugging. This is because failings in the specification and design are often only discovered through testing and understanding these failings and how to correct them comes from debugging. These observations suggest that embedded software should be designed in a way which makes testing and debugging easier and that tools which support these activities are required. Due to the often hostile environment in which the finished embedded system will function, it is necessary to have a platform which allows the software to be developed and tested "in vitro". The Testbed system achieves these goals by providing dynamic modification and process migration facilities for use during development as well as powerful monitoring and background debugging support. These facilities are built on a basic run-time harness supporting an event-driven programming model with a global communication mechanism. This programming model is well suited to the reactive nature of embedded systems. The main research contributions of this work are in the areas of finding deadlock-free, path-optimal routings for networks and of dynamic modification with automated conversion of data which may include pointers

Processor allocator for chip multiprocessors

Chip MultiProcessor (CMP) architectures consisting of many cores connected through Network-on-Chip (NoC) are becoming main computing platforms for research and computer centers, and in the future for commercial solutions. In order to effectively use CMPs, operating system is an important factor and it should support a multiuser environment in which many parallel jobs are executed simultaneously. It is done by the processor management system of the operating system, which consists of two components: Job Scheduler (JS) and Processor Allocator (PA). The JS is responsible for job scheduling that deals with selection of the next job to be executed, while the task of the PA is processor allocation that selects a set of processors for the job selected by the JS. In this thesis, the PA architecture for the NoC-based CMP is explored. The idea of the PA hardware implementation and its integration on one die together with processing elements of CMP is presented. Such an approach requires the PA to be fast as well as area and energy efficient, because it is only a small component of the CMP. The architecture of hardware version of a PA is presented. The main factor of the structure is a type of processor allocation algorithm, employed inside. Thus, all important allocation techniques are intensively investigated and new schemes are proposed. All of them are compared using experimentation system. The PA driven by the described allocation techniques is synthesized on FPGA and crucial energy and area consumption together with performance parameters are extracted. The proposed CMP uses NoC as interconnection architecture. Therefore, all main NoC structures are studied and tested. Most important parameters such as topology, flow control and routing algorithms are presented and discussed. For the proposed NoC structures, an energy model is proposed and described. Finally, the synthesized PAs and NoCs are evaluated in a simulation system, where NoC-based CMP is created. The experimental environment took into consideration energy and traffic balance characteristics. As a result, the most efficient PA and NoC for CMP are presented

Optimization of communication intensive applications on HPC networks

Communication is a necessary but overhead inducing component of parallel programming. Its impact on application design and performance is due to several related aspects of a parallel job execution: network topology, routing protocol, suitability of algorithm being used to the network, job placement, etc. This thesis is aimed at developing an understanding of how communication plays out on networks of high performance computing systems and exploring methods that can be used to improve communication performance of large scale applications. Broadly speaking, three topics have been studied in detail in this thesis. The first of these topics is task mapping and job placement on practical installations of torus and dragonfly networks. Next, use of supervised learning algorithms for conducting diagnostic studies of how communication evolves on networks is explored. Finally, efficacy of packet-level simulations for prediction-based studies of communication performance on different networks using different network parameters is analyzed. The primary contribution of this thesis is development of scalable diagnostic and prediction methods that can assist in the process of network designing, adapting applications to future systems, and optimizing execution of applications on existing systems. These meth- ods include a supervised learning approach, a functional modeling tool (called Damselfly), and a PDES-based packet level simulator (called TraceR), all of which are described in this thesis