CSE 120 Lecture Notes - Lecture 12: Working Set, Readwrite, Busy Waiting
27 Feb 2018
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Resident set - process" pages in physical memory. Need: how big the set is, and which pages. If a process needs to bring in a page, it has to kick out one of its existing pages. Global approach: select any frame (from any process) Lose isolation - processes can negatively affect another. Multiprogramming level - the # of processes in physical memory (i. e. non-empty resident sets) Processor utilization - how busy a process is doing useful work (not busy waiting, or time it takes to execute a context switch) Goal: as mp level increases, so does process utilization. Note: not all processes are compute-bound - i. e. only use the cpu. Thrashing: we don"t want a whole bunch of processes asking for resources, and then they are all busy-waiting to get them. That"s why you see the curve crashing down at the end. We want the resident set to be part of the working set.
