kumar@uunet.UU.NET (Vipin Kumar) (02/26/88)
The following reports are available: Parallel Depth First Search on the Ring Architecture by Vipin Kumar, V. Nageshwara Rao and K. Ramesh, Department of Computer Sciences, University of Texas at Austin, January 1988. Abstract: This paper presents the implementation and analysis of parallel depth-first search on the ring architecture. The effectiveness of the parallel formulation is strongly influenced by the choice of work distribution scheme that divides the work between different processors. We found that a most commonly used work distribution scheme gives very poor performance on large rings( > 32 processors). We present a new work distribution scheme that is better than the work distribution scheme used by other researchers, and gives good performance even on large rings (128 processors). We introduce the concept of iso-efficiency function to characterize the effectiveness of different work distribution schemes. The iso-efficiency function has been found quite useful in characterizing the scalability of many other parallel algorithms as well. Concurrent Access of Priority Queues by V.N. rao and Vipin Kumar, Department of Computer Sciences, University of Texas at Austin, January 1988. Abstract: The heap is an important data structure used as a priority queue in a wide variety of parallel algorithms (e.g., multiprocessor scheduling, branch-and-bound). In these algorithms, contention for for the shared heap limits the obtainable speedup. This paper presents an approach to allow concurrent insertions and deletions on the heap. Our scheme has much smaller overhead and gives a much better performance than a previously reported scheme. The scheme also retains the strict priority ordering of the serial access heap algorithms; i.e., a delete operation returns the best key of all keys that have been inserted or are being inserted at the time delete is started. Our experimental results on the BBN Butterfly parallel processor demonstrate that the use of concurrent-heap algorithms in parallel branch-and-bound improves its performance substantially. To get a copy, write or send mail to US Mail: Dr. Vipin Kumar Assistant Professor Computer science Department University of Texas at Austin Austin, TX 78712 Arpanet: kumar@sally.utexas.edu uucp: ....{harvard,ihnp4}!ut-sally!kumar