INVERTED PAGE TABLE | MEMORY MANAGEMENT | OPERATING SYSTEMS

Most of the Operating Systems implement a separate pagetable for each process, i.e. for ‘n’ number of processes running on a Multiprocessing/ Timesharing operating system, there are ‘n’ number of pagetables stored in the memory. Sometimes when a process is very large in size and it occupies virtual memory then with the size of the process, it’s pagetable size also increases substantially. An alternate approach is to use the Inverted Page Table structure that consists of one-page table entry for every frame of the main memory. So the number of page table entries in the Inverted Page Table reduces to the number of frames in physical memory and a single page table is used to represent the paging information of all the processes. Through the inverted page table, the overhead of storing an individual page table for every process gets eliminated and only a fixed portion of memory is required to store the paging information of all the processes together. This technique is called as inverted paging as the indexing is done with respect to the frame number instead of the logical page number. Each entry in the page table contains the following fields. Page number – It specifies the page number range of the logical address. Process id – An inverted page table contains the address space information of all the processes in execution. Since two different processes can have similar set of virtual addresses, it becomes necessary in Inverted Page Table to store a process Id of each process to identify it’s address space uniquely. This is done by using the combination of PId and Page Number. So this Process Id acts as an address space identifier and ensures that a virtual page for a particular process is mapped correctly to the corresponding physical frame. Control bits – These bits are used to store extra paging-related information. These include the valid bit, dirty bit, reference bits, protection and locking information bits. Chained pointer – It may be possible sometime that two or more processes share a part of main memory. In this case, two or more logical pages map to same Page Table Entry then a chaining pointer is used to map the details of these logical pages to the root page table. 00:00 - Introduction 00:23 - Overview about paging 06:52 - Drawbacks of page table 09:04 - Inverted page table 14:40 - Limitations of inverted page table #invertedpagetable #operatingsystems #parnikatutorials Instagram:   / parnikatutorials   Website: www.parnikatutorials.in Email id: [email protected] To get the regular updates: Telegram link: https://t.me/Parnikatutorials Facebook: https://m.facebook.com/profile.php?id... Linkedin:   / parnika-tutorials-a8a9831b2   Pinterest:   / parnikatutorials0892   Playlists: Virtual Coffee with Jagadeesh:    • VIRTUAL COFFEE WITH JAGADEESH   Digital Logic:    • ABOUT PARNIKA TUTORIALS   Computer Organization and Architecture:    • ABOUT PARNIKA TUTORIALS   C Programming:    • L 1: WHAT IS AN ALGORITHM AND CHARACTERIST...   Data Structures:    • L 1: Uncover the Benefits of Linked List: ...   Theory of Computation:    • ABOUT PARNIKA TUTORIALS   Compiler Design:    • ABOUT PARNIKA TUTORIALS   Operating Systems:    • PROCESS STATE DIAGRAM | LONG TERM, SHORT T...   Databases:    • ABOUT PARNIKA TUTORIALS   Computer Networks:    • ABOUT PARNIKA TUTORIALS   For GATE PYQs and much more explore:    / parnikatutorials