Single-level page tables, Operating System

Assignment Help:

As mentioned above, page tables, are lookup tables mapping a process' virtual pages to physical pages in RAM. How would one implement these page tables?

The most straightforward approach would simply have a single linear array of page-table entries (PTEs). Each PTE contains information about the page, such as its physical page number ("frame" number) as well as status bits, such as whether or not the page is valid, and other bits to be discussed later.

If we have a 32-bit architecture with 4k pages, then we have 2 pages, as discussed in the last lecture. If each PTE is 4 bytes, then each page table requires 4 Mbytes of memory. And remember that each process needs its own page table, and theremay be on the order of 100 processes running on a typical personal computer. This would require on the order of 400 Mbytes of RAM just to hold the page tables on a typical desktop!

Furthermore, many programs have a very sparse virtual address space. The vast majority of their PTEs would simply be marked  invalid.Clearly, we need a better solution than single-level page tables.


Related Discussions:- Single-level page tables

Explain lru enhanced second chance algorithm, Enhanced Second chance algori...

Enhanced Second chance algorithm In this a modify bit is as well used. Now if the ordered pair of reference and modify is (0,0) neither recently used nor modified - the best

Major advantage of the layered approach to system design, Q. What is the ma...

Q. What is the major advantage of the layered approach to system design? What are the de-merits of using the layered approach? Answer: As in all cases of modular design as well

Differences among user-level threads and kernel-level thread, What are two ...

What are two differences among user-level threads and kernel-level threads? Under what circumstances is one type better than the other? (1) User-level threads are unknown by th

Explain segmentation and paging, Why are segmentation and paging sometimes ...

Why are segmentation and paging sometimes combined into one scheme? Segmentation and paging are often combined in order to improve upon each other. Segmented paging is helpful

Most-recently used algorithm, Evicting the most-recently used (MRU) page do...

Evicting the most-recently used (MRU) page does very well on LRU's worst case. In general, however, MRU is a bad idea, since many programs exhibit temporal locality in their memory

Kernel to context switch between kernel level threads, Q. Explain the actio...

Q. Explain the actions taken by a kernel to context switch between kernel level threads. Answer: Context switching among kernel threads classically requires saving the value

What is paging? name the different paging techniques, What is paging? Name ...

What is paging? Name the different paging techniques. Paging is a memory management method that permits the physical-address space of a process to be noncontiguous. Paging evad

Briefly discuss on page replacement, Briefly discuss on page replacement? ...

Briefly discuss on page replacement? Page replacement approach is fixed as follows. If no frame is free, we search one that is not presently being used and free it. We can fre

Unix, UNIX Shell and History feature. 1.Creating a child process. 2.Creatin...

UNIX Shell and History feature. 1.Creating a child process. 2.Creating a history feature. With the notes under code. Its exactly "programming project 1 - Unix Shell and History Fea

Custom memory allocation, Some people write custom memory allocators to mee...

Some people write custom memory allocators to meet their speci?c needs. Although this is not needed for most of the applications, it is also not uncommon. The goal, of course, is t

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd