Using Reference Counters in Update-Based Coherent Memory

As the disparity between processor and memory speed continues to widen the exploita tion of locality of reference in shared memory multiprocessors becomes an increasingly important problem in parallel processing In this paper we explore the problem of managing locality at the operating system level In speci c we study the use of reference counters in making informed deci sions about page placement and movement We use trace driven simulation of real applications to evaluate the e ectiveness of reference counters in providing useful hints to the memory manager of the operating system Our main conclusion is that reference counters provide a simple and inex pensive mechanism for detecting the reference patterns of pages and making robust page placement decisions that result in signi cant performance improvement