Paging and Addressing in the VM-DP System

Abstract

denotes the number of bytes of RAM, and B denotes the number of bytes per disk block. Accordingly, the track size BD is also measured in bytes. We use bytes rather than records because Vcode, the stack-based, intermediate, dataparallel language that is interpreted by VM-DP supports two different record sizes: 4-byte integers and 8-byte floats. Normalizing all sizes to bytes makes our descriptions independent of record sizes. When does VM-DP use demand paging? All operations that access vectors use VM-DP's demand-paging system. Operations other than the permuting operations use it for all their vector accesses. These operations include all elementwise operations, scans, and reduces. In addition, Vcode includes six different operations that permute according to target addresses. These permuting operations go through the paging system at least part of the time; they disable it only during external radix sor