2000 IEEE Asilomar Conf. on Signals, Systems, and Computers

Optimization of Vertical and Horizontal Beamforming Kernels on the PowerPC G4 Processor with AltiVec Technology

Young H. Cho, David Brunke, Gregory E. Allen, and Brian L. Evans

Department of Electrical and Computer Engineering, Engineering Science Building, The University of Texas at Austin, Austin, TX 78712-1084 USA
young@ece.utexas.edu - brunke@ece.utexas.edu - allen@ece.utexas.edu - bevans@ece.utexas.edu

Paper - Talk

Abstract

Three-dimensional real-time digital sonar beamforming requires 4 to 12 GFLOPS, 1 to 2 GB of memory, and about 100 MB/s of I/O bandwidth. Allen and Evans have implemented a 4-GFLOP sonar beamformer in real-time on a Sun UltraSPARC II server with 16 333-MHz processors by utilizing the Visual Instruction Set (VIS) single-instruction multiple-data (SIMD) extensions. In this paper, we rewrite the horizontal and vertical beamforming kernels to use AltiVec SIMD extension for the PowerPC. AltiVec can execute up to four 32-bit floating-point multiply and accumulate (MAC) operations per instruction. In the PowerPC implementation, we prefetch and realign data for the 128-bit SIMD registers of AltiVec. We evaluate the performance of these beamforming kernels on the PowerPC and the UltraSPARC-II to evaluate the impact of the compiler, SIMD word alignment, and cache block alignment on performance.

Last Updated 11/09/00.