Browsing by Author "Das, Raja"
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Item A Framework for Optimizing Parallel I/O(1998-10-15) Bennett, Robert; Bryant, Kelvin S.; Sussman, Alan; Das, Raja; Saltz, JoelThere has been a great deal of recent interest in parallel I/O. This paper discusses issues in the design and implementation of a portable I/O library designed to optimize the performance of multiprocessor architectures that include multiple disks or disk arrays. The major emphasis of the paper is on optimizations that are made possible by the use of collective I/O, so that I/O requests for multiple processors can be combined to improve performance. Performance measurements from benchmarking our implementation of an I/O library that currently performs collective local optimizations, called Jovian, on three application templates are also presented.Item Interprocedural Partial Redundancy Elimination and its Application to Distributed Memory Compilation(1998-10-15) Agrawal, Gagan; Saltz, Joel; Das, RajaPartial Redundancy Elimination (PRE) is a general scheme for suppressing partial redundancies which encompasses traditional optimizations like loop invariant code motion and redundant code elimination. In this paper we address the problem of performing this optimization interprocedurally. We use interprocedural partial redundancy elimination for placement of communication and communication preprocessing statements while compiling for distributed memory parallel machines. (Also cross-referenced as UMIACS-TR-95-42)Item A Manual for the CHAOS Runtime Library(1998-10-15) Saltz, Joel; Ponnusamy, Ravi; Sharma, Shamik D.; Moon, Bongki; Hwang, Yuan-Shin; Uysal, Mustafa; Das, RajaProcedures are presented that are designed to help users efficiently program irregular problems (e.g. unstructured mesh sweeps, sparse matrix codes, adaptive mesh partial dif- ferential equations solvers) on distributed memory machines. These procedures are also designed for use in compilers for distributed memory multiprocessors. The portable CHAOS pro- cedures are designed to support dynamic data distributions and to automatically generate send and receive messsage by capturing communications patterns at runtime. (Also cross-referenced as UMIACS-TR-95-34)Item Run-time and Compile-time Support for Adaptive Irregular Problems(1998-10-15) Sharma, Shamik D.; Ponnusamy, Ravi; Moon, Bongki; Hwang, Yuan-Shin; Das, Raja; Saltz, JoelIn adaptive irregular problems the data arrays are accessed via indirection arrays, and data access patterns change during computation. Implementing such problems on distributed memory machines requires support for dynamic data partitioning, efficient preprocessing and fast data migration. This research presents efficient runtime primitives for such problems. This new set of primitives is part of the CHAOS library. It subsumes the previous PARTI library which targeted only static irregular problems. To demonstrate the efficacy of the runtime support, two real adaptive irregular applications have been parallelized using CHAOS primitives: a molecular dynamics code (CHARMM) and a particle-in-cell code (DSMC). The paper also proposes extensions to Fortran D which can allow compilers to generate more efficient code for adaptive problems. These language extensions have been implemented in the Syracuse Fortran 90D/HPF prototype compiler. The performance of the compiler parallelized codes is compared with the hand parallelized versions. (Also cross-referenced as UMIACS-TR-94-55)