Results 1 
2 of
2
Performance of WorkOptimal PRAM Simulation Algorithms on Coated Meshes
, 1996
"... We study the effect of varying the multithreading level of processors in workoptimal PRAM simulation algorithms on coated meshes. A coated mesh consists of a mesh connected routing machinery and P processor &memory pairs that form a coat on the routing machinery. The algorithms studied are base ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
We study the effect of varying the multithreading level of processors in workoptimal PRAM simulation algorithms on coated meshes. A coated mesh consists of a mesh connected routing machinery and P processor &memory pairs that form a coat on the routing machinery. The algorithms studied are based on greedy routing, sorting, improved virtual leveled network technique, combining queues method, and synchronization wave. Our results show that increasing the multithreading level considerably improves the simulation cost. The cost can be decreased below 5 routing steps per P simulated PRAM processors. In case of one algorithm, even costs 1:1 : : : 2 are achieved. 1 Introduction Workoptimal simulation of PRAM models means that a constant fraction of the aggregate power of processors can be given to (arbitrary) PRAM computations. We study the efficiency of five PRAM simulation algorithms on a structure called coated mesh. This is interesting, since (a) the coated mesh (rigid definition is g...
DataIndependence of Read, Write, and Control Structures in PRAM computations
, 1998
"... We introduce the notions of control and communication structures in PRAM computations and relate them to the concept of dataindependence. Our main result is to characterize differences between unbounded fanin parallelism AC k , bounded fanin parallelism NC k , and the sequential classes DSPA ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
We introduce the notions of control and communication structures in PRAM computations and relate them to the concept of dataindependence. Our main result is to characterize differences between unbounded fanin parallelism AC k , bounded fanin parallelism NC k , and the sequential classes DSPACE(logn) and LOGDCFL in terms of a PRAM's communication structure and instruction set. Our findings give a concrete indication that in parallel computations writing is more powerful than reading. Further characterizations are given for parallel pointer machines and the semiunbounded fanin circuit classes SAC k . In particular, we obtain the first characterizations of NC k and DSPACE(logn) in terms of PRAM's. Finally, we introduce IndexPRAM's which in some sense have "builtin dataindependence." We propose IndexPRAM's as a tool for the development of dataindependent parallel algorithms. IndexPRAM's serve for studying the essential differences between the above mentioned complexity classes with respect to the underlying instruction set used.