BIB-VERSION:: CS-TR-v2.0
ID:: ncstrl.dartmouthcs//TR96-293
ENTRY:: August 07, 1996
ORGANIZATION:: Dartmouth College, Computer Science
TITLE:: Early Experiences in Evaluating the Parallel Disk Model with the ViC* Implementation
TYPE:: Technical Report (paper)
REVISION:: 3
AUTHOR:: Cormen, Thomas H.
AUTHOR:: Hirschl, Melissa
DATE:: September 1996
RETRIEVAL:: For a paper copy, email <reports@cs.dartmouth.edu>
RETRIEVAL:: For a paper copy, write to
       Technical Report Librarian
       Department of Computer Science
       Dartmouth College
       6211 Sudikoff Laboratory
       Hanover, NH 03755-3510
       USA
RETRIEVAL:: Compressed Postscript at http://www.cs.dartmouth.edu/reports/TR96-293.ps.Z
RETRIEVAL:: PDF at http://www.cs.dartmouth.edu/reports/TR96-293.pdf
ABSTRACT:: 
Although several algorithms have been developed for the Parallel Disk
Model (PDM), few have been implemented.  Consequently, little has been
known about the accuracy of the PDM in measuring I/O time and total
time to perform an out-of-core computation.  This paper analyzes
timing results on a uniprocessor with several disks for two PDM
algorithms, out-of-core radix sort and BMMC permutations, to determine
the strengths and weaknesses of the PDM.
	The results indicate the following.  First, good PDM
algorithms are usually not I/O bound.  Second, of the four PDM
parameters, two (problem size and memory size) are good indicators of
I/O time and running time, but the other two (block size and number of
disks) are not.  Third, because PDM algorithms tend not to be I/O
bound, asynchronous I/O effectively hides I/O times.
	The software interface to the PDM is part of the ViC* run-time
library.  The interface is a set of wrappers that are designed to be
both efficient and portable across several parallel file systems and
target machines.
NOTE:: 
Revised version appeared in Parallel Computing 23(4), June 1997.  
Original version August 7, 1996; revised version September 6, 1996.
END:: ncstrl.dartmouthcs//TR96-293