# LogP: Towards a Realistic Model of Parallel Computation

### David E. Culler, Richard Karp, David A. Patterson, Abhijit Sahay, Klaus Erik Schauser, Eunice Santos, Ramesh Subramonian and Thorsten von Eicken

###
EECS Department

University of California, Berkeley

Technical Report No. UCB/CSD-92-713

December 1992

### http://www.eecs.berkeley.edu/Pubs/TechRpts/1992/CSD-92-713.pdf

A vast body of theoretical research has focused either on overly simplistic models of parallel computation, notably the PRAM, or overly specific models that have few representatives in the real world. Both kinds of models encourage exploitation of formal loopholes, rather than rewarding development of techniques that yield performance across a range of current and future parallel machines. This paper offers a new parallel machine model, called LogP, that reflects the critical technology trends underlying parallel computers. It is intended to serve as a basis for developing fast, portable parallel algorithms and to offer guidelines to machine designers. Such a model must strike a balance between detail and simplicity in order to reveal important bottlenecks without making analysis of interesting problems intractable. The model is based on four parameters that specify abstractly the computing bandwidth, the communication bandwidth, the communication delay, and the efficiency of coupling communication and computation. Portable parallel algorithms typically adapt to the machine configuration, in terms of these parameters. The utility of the model is demonstrated through examples that are implemented on the CM-5.

Keywords: massively parallel processors, parallel models, complexity analysis, parallel algorithms, PRAM

BibTeX citation:

@techreport{Culler:CSD-92-713, Author = {Culler, David E. and Karp, Richard and Patterson, David A. and Sahay, Abhijit and Schauser, Klaus Erik and Santos, Eunice and Subramonian, Ramesh and von Eicken, Thorsten}, Title = {LogP: Towards a Realistic Model of Parallel Computation}, Institution = {EECS Department, University of California, Berkeley}, Year = {1992}, Month = {Dec}, URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/1992/6262.html}, Number = {UCB/CSD-92-713}, Abstract = {A vast body of theoretical research has focused either on overly simplistic models of parallel computation, notably the PRAM, or overly specific models that have few representatives in the real world. Both kinds of models encourage exploitation of formal loopholes, rather than rewarding development of techniques that yield performance across a range of current and future parallel machines. This paper offers a new parallel machine model, called LogP, that reflects the critical technology trends underlying parallel computers. It is intended to serve as a basis for developing fast, portable parallel algorithms and to offer guidelines to machine designers. Such a model must strike a balance between detail and simplicity in order to reveal important bottlenecks without making analysis of interesting problems intractable. The model is based on four parameters that specify abstractly the computing bandwidth, the communication bandwidth, the communication delay, and the efficiency of coupling communication and computation. Portable parallel algorithms typically adapt to the machine configuration, in terms of these parameters. The utility of the model is demonstrated through examples that are implemented on the CM-5. <p>Keywords: massively parallel processors, parallel models, complexity analysis, parallel algorithms, PRAM} }

EndNote citation:

%0 Report %A Culler, David E. %A Karp, Richard %A Patterson, David A. %A Sahay, Abhijit %A Schauser, Klaus Erik %A Santos, Eunice %A Subramonian, Ramesh %A von Eicken, Thorsten %T LogP: Towards a Realistic Model of Parallel Computation %I EECS Department, University of California, Berkeley %D 1992 %@ UCB/CSD-92-713 %U http://www.eecs.berkeley.edu/Pubs/TechRpts/1992/6262.html %F Culler:CSD-92-713