%T Low-level Interfaces for High-level Parallel I/O
%A Nils Nieuwejaar
%A David Kotz
%R Technical Report PCS-TR95-253
%I Dartmouth College, Computer Science
%C Hanover, NH
%D March 1995
%U http://www.cs.dartmouth.edu/reports/TR95-253.ps.Z
%X
 As the I/O needs of parallel scientific applications increase, file
 systems for multiprocessors are being designed to provide applications
 with parallel access to multiple disks.  Many parallel file systems
 present applications with a conventional Unix-like interface that
 allows the application to access multiple disks transparently.  By
 tracing all the activity of a parallel file system in a production,
 scientific computing environment, we show that many applications
 exhibit highly regular, but non-consecutive I/O access patterns.
 Since the conventional interface does not provide an efficient method
 of describing these patterns, we present three extensions to the
 interface that support strided, nested-strided, and nested-batched I/O
 requests.  We show how these extensions can be used to express common
 access patterns.
%Z
 This TR supercedes PCS-TR94-230.
 A result of the <A HREF="/~dfk/charisma.html">CHARISMA project</A>.
 Appeared in <A HREF="/iopads/iopads95/">IOPADS '95</A> at IPPS '95.