Coalescing what do we do with a block that has just

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Unformatted text preview: o other processes, and any writes that the process makes to the area are not reflected back to the object on disk. A virtual memory area that a shared object is mapped into is often called a shared area. Similarly for a private area. Suppose that process 1 maps a shared object into an area of its virtual memory, as shown in Figure 10.31(a). Now suppose that process 2 maps the same shared object into its address space (not necessarily at the same virtual address as process 1) as shown in Figure 10.31(b). Since each object has a unique file name, the kernel can quickly determine that process 1 has already mapped this object and can point the page table entries in process 2 to the appropriate physical pages. The key point is that only a single copy of the shared object needs to be stored in physical memory, even though the object is mapped into multiple shared areas. For convenience, we have shown the physical pages as being contiguous, but of course this is not true in general. Private objects are mapped into virtual me...
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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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