PARALLEL DISTRIBUTED SEISMIC MIGRATION

We report significant speed-up for seismic migration running in parallel on network-connected IBM RISC/6000 workstations. A sustained performance of 15 MFLOP is obtained on a single-entry-level model 320, and speed-ups as high as 5 are obtained for six workstations connected by Ethernet or token ring. Our parallel software usa remote procedure calls provided by NCS (Network Computing System). We have run over a dozen workstations in parallel, but speed-ups become limited by network data rate. Fiber-optic communication should allow much greater speed-ups, and we describe our preliminary results with the fiber-optic serial link adapter of the RISC/6000. We also present a simple theoretical model that agrees well with our measurements and allows speed-up to be predicted from a knowledge of the ratio of computation to communication, which can be determined empirically before the program is parallelized. We conclude with a brief discussion of alternative software approaches and programming models for network-connected parallel systems. In particular, our program was recently ported to PVM and Linda, and preliminary measurements yield speed-ups very close to those described here.