|BERT 77 Executive Summary|
The BERT 77 (or "BERT") software tool attempts to automatically and efficiently convert sequential FORTRAN 77 programs for a parallel computing environment. BERT produces code that is compatible with the standard message passing model supported by PVM and MPI. Although the current BERT output assumes the message passing model, it is possible to use the analysis provided by BERT to assist with shared memory parallelizations supported by the hardware vendors. Like most other conversion tools BERT provides two important features:
In contrast to many other conversion tools, however, BERT examines the concurrent parts of your program to see whether they should be executed in parallel. BERT understands that overall performance depends upon how efficiently concurrent portions of your program can be executed on separate processors in parallel. Without considering computation times and communication times, there is no guarantee that concurrent portions of your program can be efficiently executed in parallel.
To determine parallel efficiency, BERT includes a scheduler between the concurrency detection and code generation portions of the program. The following figure shows how the scheduler fits into the generalized conversion process. The BERT scheduler requires that any portion executed in parallel provide an execution speed-up. Concurrent portions of your program that are not found to be efficient are not converted to parallel by BERT (unless you override BERT's decision).
BERT makes efficiency decisions by consulting a machine information file for each target host parallel computer. The machine information file contains execution and communication times so that BERT can determine whether concurrent portions should be executed in parallel.
Based on previous experience, completely converting a program on the first pass is a rare event. Programs often contain "parallelization inhibitors" (recursive variables or loop carried dependencies) which are detected by BERT. Quite often, the program was written without regard to parallelization or parallel efficiency. BERT provides a solution to this problem by providing a rapid and cost effective method to analyze and convert sequential FORTRAN 77 applications to efficient parallel programs.
The following are some of the features and benefits you can expect from BERT.
Expected Benefits After Using BERT for Several Hours
Expected Benefits After Using BERT for Several Days
|Last Updated ( Monday, 17 July 2006 )|