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Silberschatz, Galvin and Gagne 2002 9.34 Operating System Concepts Two-Level Page-Table Scheme
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Silberschatz, Galvin and Gagne 2002 9.35 Operating System Concepts Address-Translation Scheme square6 Address-translation scheme for a two-level 32-bit paging architecture
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Silberschatz, Galvin and Gagne 2002 9.36 Operating System Concepts Hashed Page Tables square6 Common in address spaces > 32 bits. square6 The virtual page number is hashed into a page table. This page table contains a chain of elements hashing to the same location. square6 Virtual page numbers are compared in this chain searching for a match. If a match is found, the corresponding physical frame is extracted.
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Silberschatz, Galvin and Gagne 2002 9.37 Operating System Concepts Hashed Page Table
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Silberschatz, Galvin and Gagne 2002 9.38 Operating System Concepts Inverted Page Table square6 One entry for each real page of memory. square6 Entry consists of the virtual address of the page stored in that real memory location, with information about the process that owns that page. square6 Decreases memory needed to store each page table, but increases time needed to search the table when a page reference occurs. square6 Use hash table to limit the search to one — or at most a few — page-table entries.
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Silberschatz, Galvin and Gagne 2002 9.39 Operating System Concepts Inverted Page Table Architecture
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Silberschatz, Galvin and Gagne 2002 9.40 Operating System Concepts Shared Pages square6 Shared code handptright One copy of read-only (reentrant) code shared among processes (i.e., text editors, compilers, window systems). handptright Shared code must appear in same location in the logical address space of all processes. square6 Private code and data handptright Each process keeps a separate copy of the code and data. handptright The pages for the private code and data can appear anywhere in the logical address space.
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Silberschatz, Galvin and Gagne 2002 9.41 Operating System Concepts Shared Pages Example
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Silberschatz, Galvin and Gagne 2002 9.42 Operating System Concepts Segmentation square6 Memory-management scheme that supports user view of memory. square6 A program is a collection of segments. A segment is a logical unit such as: main program, procedure, function, method, object, local variables, global variables, common block, stack, symbol table, arrays
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Silberschatz, Galvin and Gagne 2002 9.43 Operating System Concepts User’s View of a Program
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Silberschatz, Galvin and Gagne 2002 9.44 Operating System Concepts Logical View of Segmentation 1 3 2 4 1 4 2 3 user space physical memory space
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Silberschatz, Galvin and Gagne 2002 9.45 Operating System Concepts Segmentation Architecture square6 Logical address consists of a two tuple: <segment-number, offset>, square6 Segment table – maps two-dimensional physical addresses; each table entry has: handptright base – contains the starting physical address where the segments reside in memory.
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