Efficient Processor Assignment Algorithms and Loop Transformations for Executing Nested Parallel Loops on Multiprocessors

An important issue for the efficient use of multiprocessor systems is the assignment of parallel processors to nested parallel loops. It is desirable for a processor assignment algorithm to be fast and always generate an optimal processor assignment. The paper proposes two efficient algorithms to decide the optimal number of processors assigned to each individual loop. Efficient parallel counterparts of these two algorithms are also presented. These algorithms not only always generate an optimal processor assignment, but also are much faster than the exiting optimal algorithm in the literature. The paper discusses improving the performance of parallel execution by transforming a nested parallel loop into a semantically equivalent one. Three loop transformations are investigated. It is observed that, in most cases, the parallel execution time is improved after applying these transformations. >

[1]  Ron Cytron,et al.  Limited Processor Scheduling of Doacross Loops , 1987, ICPP.

[2]  E.L. Lawler,et al.  Optimization and Approximation in Deterministic Sequencing and Scheduling: a Survey , 1977 .

[3]  Harold S. Stone,et al.  Multiprocessor Scheduling with the Aid of Network Flow Algorithms , 1977, IEEE Transactions on Software Engineering.

[4]  Ron Cytron,et al.  Doacross: Beyond Vectorization for Multiprocessors , 1986, ICPP.

[5]  Alexander V. Veidenbaum,et al.  EFFECTS OF PROGRAM RESTRUCTURING, ALGORITHM CHANGE, AND ARCHITECTURE CHOICE ON PROGRAM PERFORMANCE. , 1984 .

[6]  Ronald Gary Cytron.  Compile-time scheduling and optimization for asynchronous machines (multiprocessor, compiler, parallel processing) , 1984 .

[7]  David Alejandro Padua Haiek.  Multiprocessors: discussion of some theoretical and practical problems , 1980 .

[8]  Chris R. Jesshope,et al.  Parallel Computers 2: Architecture, Programming and Algorithms , 1981 .

[9]  Ken Kennedy,et al.  PFC: A Program to Convert Fortran to Parallel Form , 1982 .

[10]  Peiyi Tang,et al.  Dynamic Processor Self-Scheduling for General Parallel Nested Loops , 1987, IEEE Trans. Computers.

[11]  Ted G. Lewis,et al.  Parallel processor balance through loop spreading , 1989, Proceedings of the 1989 ACM/IEEE Conference on Supercomputing (Supercomputing '89).

[12]  CONSTANTINE D. POLYCHRONOPOULOS,et al.  Guided Self-Scheduling: A Practical Scheduling Scheme for Parallel Supercomputers , 1987, IEEE Transactions on Computers.

[13]  Michael J. Quinn,et al.  Designing Efficient Algorithms for Parallel Computers , 1987 .

[14]  Reinhard Männer.  Hardware Task/Processor Scheduling in a Polyprocessor Environment , 1984, IEEE Trans. Computers.

[15]  Alexander V. Veidenbaum.  Compiler optimizations and architecture design issues for multiprocessors (parallel) , 1985 .

[16]  David A. Padua,et al.  Execution of Parallel Loops on Parallel Processor Systems , 1986, ICPP.

[17]  Alexandru Nicolau,et al.  Parallel processing: a smart compiler and a dumb machine , 1984, SIGPLAN '84.

[18]  David A. Padua,et al.  Utilizing Multidimensional Loop Parallelism on Large-Scale Parallel Processor Systems , 1989, IEEE Trans. Computers.

[19]  Constantine D. Polychronopoulos,et al.  Processor Allocation for Horizontal and Vertical Parallelism and Related Speedup Bounds , 1987, IEEE Transactions on Computers.