Memory-reference characteristics of multiprocessor applications under MACH

Shared-memory multiprocessors have received wide attention in recent times as a means of achieving high-performance cost-effectively. Their viability requires a thorough understanding of the memory access patterns of parallel processing applications and operating systems. This paper reports on the memory reference behavior of several parallel applications running under the MACH operating system on a shared-memory multiprocessor. The data used for this study is derived from multiprocessor address traces obtained from an extended ATUM address tracing scheme implemented on a 4-CPU DEC VAX 8350. The applications include parallel OPS5, logic simulation, and a VSLI wire routing program. Among the important issues addressed in this paper are the amount of sharing in user programs and in the operating system, comparing the characteristics of user and system reference patterns, sharing related to process migration, and the temporal, spatial, and processor locality of shared blocks. We also analyze the impact of shared references on cache coherence in shared-memory multiprocessors.