Thus we need to store only the 29 high order bits of

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Unformatted text preview: mory using a clever technique known as copy-on-write. A private object begins life in exactly the same way as a shared object, with only one copy of the private object stored in physical memory. For example, Figure 10.32(a) shows a case where two processes have mapped a private object into different areas of their virtual memories, but share the same physical copy of the object. For each process that maps the private object, the page table entries for the corresponding private area are flagged as read-only, and the area struct is flagged as private copy-on-write. So long as neither process attempts to write to its respective private area, they continue to share a single copy of the object in physical memory. However, as soon as a process attempts to write to some page in the private area, the write triggers 518 CHAPTER 10. VIRTUAL MEMORY Process 1 virtual memory Physical memory Process 2 virtual memory Process 1 virtual memory Physical memory Process 2 virtual memory Shared object Shared object...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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