We introduce a formalism which allows to treat computer architecture as a formal optimization problem. We apply this to the design of shared memory parallel machines. Present computers of this type support the programming model of a shared memory. But simultaneous access to the shared memory by several processors is in many situations processed sequentially. Asymptotically good solutions for this problem are offered by theoretical computer science. We modify these constructions under engineering aspects and improve the price/performance ratio by roughly a factor of 6. The resulting machine has surprisingly good price/performance ratio even if compared with distributed memory machines. For almost all access patterns of all processors into the shared memory, access is as fast as the access of only a single processor. 1 Introduction Commercially available parallel machines can be classified as distributed memory machines or shared memory machines. Exchange of data between different proce...

We analyze the complexity of simulating a PRAM (parallel random access machine) on a mesh structured distributed memory machine. By utilizing suitable algorithms for randomized hashing, routing in a mesh, and sorting in a mesh, we prove that simulation of a PRAM on p N \Theta p N (or 3 p N \Theta 3 p N \Theta 3 p N ) mesh is possible with O( p N ) (respectively O( 3 p N )) delay with high probability and a relatively small constant. Furthermore, with more sophisticated simulations further speed-ups are achieved; experiments show delays as low as p N + o( p N ) (respectively 3 p N + o( 3 p N )) per N PRAM processors. These simulations compare quite favorably with PRAM simulations on butterfly and hypercube. 1 Introduction PRAM 1 (Parallel Random Access Machine) is an abstract model of computation. It consists of N processors, each of which may have some local memory and registers, and a global shared memory of size m. A step of a PRAM is often seen to consist of...

In this paper we consider the effect of overloading in four work-optimal PRAM simulation algorithms on coated meshes with P real processors. A coated mesh consists of a mesh connected routing machinery, and processor&memory pairs, which form a coat on the routing machinery. Previously work-optimal PRAM simulations, which ignore the effect of overloading, has been presented for coated meshes, but their cost is relatively high (around 100). The algorithms we study here are based on greedy routing, sorting, improved virtual levelled network technique, and combining queues method. Our results show that overloading alone can be used to improve the simulation cost of all PRAM models on coated meshes to circa 10 (and even less) routing steps per P simulated PRAM processors. 1 Introduction In [13] three algorithms for simulating PRAM models on coated meshes were presented (see also [15, 16]). The EREW PRAM simulation algorithm was based on a modification of the basic greedy routing algorithm ...

We present an improved version of the virtual leveled network routing strategy for mesh connected computers. This improvement achieves a speedup of approximately 2, and requires practically no additional hardware. We confirm this by providing experimental results concerning time to accomplish CRCW PRAM simulation influenced routing situations. 1 Introduction Combining messages during a routing process is the method to avoid performance degradation in the presence of hot-spots. Especially, combining on the route provides a practical method to accomplish the memory reference primitives of strong CRCW PRAM (as well as CREW) models. Several methods have been proposed to accomplish combining [1, 3, 6, 8, 10], which all can be applied to mesh connected computers. These methods can be applied to other interconnection structures as well, but here we deal only with the 2-dimensional and the 3-dimensional mesh structure, since it is simple, regular, modularly extendible, well scalable, and in g...

A lot of experimental results were provided in [2] for the coated meshes [6] using the improved virtual levelled network routing strategy [3]. In this report we give the source listing of simulation programs (and tools to analyze the results) that were used to produce the mentioned results. i ii Contents 1 Introduction 1 1.1 Structure of programs : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 1.2 Organization of this document : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 Virtual leveled network approach on ordinary meshes 5 2.1 Ordinary 2-dimensional mesh : : : : : : : : : : : : : : : : : : : : : : : : : : : 5 2.2 Ordinary 3-dimensional mesh : : : : : : : : : : : : : : : : : : : : : : : : : : : 27 2.3 Shell scripts : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 54 2.3.1 m32w2 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 54 2.3.2 m10w3 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :...