Recent questions tagged memory-management

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Self Doubt:Paging
I have read that paging does not suffer from external fragmentation as the frames and the pages are all of the equal sizes, but when we store a last level page table in a frame at that time it may not fully occupy the frame. Similarly, if ... exceed a page size. Then there should be external fragmentation, right? So why is it said that paging does not have external fragmentation?

asked Jun 13 in Operating System by Hirak Active (3k points) | 51 views

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Mode of OS during page table access
What is the mode(User/Kernel) of the Operating System when a Page Table or TLB are being accessed?

asked May 18 in Operating System by !KARAN Active (1.8k points) | 36 views

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Galvin Edition 9 Exercise 9 Question 38 (Page No. 456)
Consider a system that allocates pages of different sizes to its processes. What are the advantages of such a paging scheme ? What modifications to the virtual memory system provide this functionality ?

asked Mar 22 in Operating System by akash.dinkar12 Boss (40.5k points) | 52 views

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Galvin Edition 9 Exercise 8 Question 32 (Page No. 393-394)
Consider the Intel address-translation scheme shown in Figure 8.22. a. Describe all the steps taken by the Intel Pentium in translating a logical address into a physical address. b. What are the advantages to the operating system of ... -translation system? If so, what are they? If not, why is this scheme not used by every manufacturer ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 33 views

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Galvin Edition 9 Exercise 8 Question 31 (Page No. 393)
Compare the segmented paging scheme with the hashed page table scheme for handling large address spaces. Under what circumstances is one scheme preferable to the other ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 22 views

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Galvin Edition 9 Exercise 8 Question 30 (Page No. 393)
Consider the hierarchical paging scheme used by the $VAX$ architecture. How many memory operations are performed when a user program executes a memory-load operation ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 12 views

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Galvin Edition 9 Exercise 8 Question 29 (Page No. 393)
What is the purpose of paging the page tables ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 9 views

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Galvin Edition 9 Exercise 8 Question 28 (Page No. 393)
Consider the following segment table: $Segment$ $Base$ $Length$ $0$ $219$ $600$ $1$ $2300$ $14$ $2$ $90$ $100$ $3$ $1327$ $580$ $4$ $1952$ $96$ What are the physical addresses for the following logical addresses ? $a. 0,430$ $b. 1,10$ $c. 2,500$ $d. 3,400$ $e. 4,112$

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 29 views

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Galvin Edition 9 Exercise 8 Question 27 (Page No. 393)
Explain why sharing a reentrant module is easier when segmentation is used than when pure paging is used.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 17 views

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Galvin Edition 9 Exercise 8 Question 26 (Page No. 393)
Why are segmentation and paging sometimes combined into one scheme ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 33 views

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Galvin Edition 9 Exercise 8 Question 25 (Page No. 393)
Consider a paging system with the page table stored in memory. a. If a memory reference takes 50 nanoseconds, how long does a paged memory reference take ? b. If we add $TLBs$, and 75 percent of all page-table references are found ... time ? (Assume that finding a page-table entry in the $TLBs$ takes 2 nanoseconds, if the entry is present.)

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 31 views

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Galvin Edition 9 Exercise 8 Question 23 (Page No. 392)
Consider a logical address space of $256$ pages with a $4-KB$ page size, mapped onto a physical memory of $64$ frames. $a$. How many bits are required in the logical address ? $b$. How many bits are required in the physical address ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 11 views

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Galvin Edition 9 Exercise 8 Question 22 (Page No. 392)
What is the maximum amount of physical memory ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 19 views

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Galvin Edition 9 Exercise 8 Question 21 (Page No. 392)
The BTV operating system has a $21-bit$ virtual address, yet on certain embedded devices, it has only a $16-bit$ physical address. It also has a $2-KB$ page size. How many entries are there in each of the following ? $a$. A conventional, single-level page table $b$. An inverted page table

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 74 views

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Galvin Edition 9 Exercise 8 Question 20 (Page No. 392)
Assuming a $1$ $KB$ page size, what are the page numbers and offsets for the following address references (provided as decimal numbers): $a. 3085$ $b. 42095$ $c. 215201$ $d. 650000$ $e. 2000001$

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 17 views

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Galvin Edition 9 Exercise 8 Question 19 (Page No. 392)
Program binaries in many systems are typically structured as follows. Code is stored starting with a small, fixed virtual address, such as $0$. The code segment is followed by the data segment that is used for storing the program ... structure for the following schemes ? $a$. Contiguous memory allocation $b$. Pure segmentation $c$. Pure paging

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 22 views

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Galvin Edition 9 Exercise 8 Question 18 (Page No. 392)
Explain why address space identifiers ($ASIDs$) are used.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 19 views

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18

Galvin Edition 9 Exercise 8 Question 17 (Page No. 392)
Compare paging with segmentation with respect to how much memory the address translation structures require to convert virtual addresses to physical addresses.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 26 views

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Galvin Edition 9 Exercise 8 Question 16 (Page No. 392)
Although Android does not support swapping on its boot disk, it is possible to set up a swap space using a separate SD nonvolatile memory card. Why would Android disallow swapping on its boot disk yet allow it on a secondary disk ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 60 views

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20

Galvin Edition 9 Exercise 8 Question 15 (Page No. 392)
Explain why mobile operating systems such as iOS and Android do not support swapping ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 19 views

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Galvin Edition 9 Exercise 8 Question 14 (Page No. 391)
On a system with paging, a process cannot access memory that it does not own. Why ? How could the operating system allow access to other memory ? Why should it or should it not ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 4 views

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22

Galvin Edition 9 Exercise 8 Question 13 (Page No. 391)
Compare the memory organization schemes of contiguous memory allocation, pure segmentation, and pure paging with respect to the following issues: $a$. External fragmentation $b$. Internal fragmentation $c$. Ability to share code across processes

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 20 views

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23

Galvin Edition 9 Exercise 8 Question 12 (Page No. 391)
Most systems allow a program to allocate more memory to its address space during execution. Allocation of data in the heap segments of programs is an example of such allocated memory. What is required to support dynamic memory allocation in the following schemes ? $a$. Contiguous memory allocation $b$. Pure segmentation $c$. Pure paging

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 8 views

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24

Galvin Edition 9 Exercise 8 Question 11 (Page No. 391)
Given six memory partitions of $300$ $KB$, $600$ $KB$, $350$ $KB$, $200$ $KB$, $750$ KB$ and $125$KB$ (in order), how would the $first-fit$, $best-fit$, and $worst-fit$ algorithms place processes of size $115$ $KB$, $500$ $KB$, $358$KB$, $200$ $KB$, and $375$ $KB$ (in order) ? Rank the algorithms in terms of how efficiently they use memory.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 14 views

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25

Galvin Edition 9 Exercise 8 Question 10 (Page No. 391)
Consider the following process for generating binaries. A compiler is used to generate the object code for individual modules, and a linkage editor is used to combine multiple object modules into a single program binary. How does ... passed from the compiler to the linkage editor to facilitate the memory-binding tasks of the linkage editor ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 8 views

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26

Galvin Edition 9 Exercise 8 Question 9 (Page No. 391)
Explain the difference between internal and external fragmentation.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 10 views

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27

Galvin Edition 9 Exercise 8 Question 8 (Page No. 390-391)
In the IBM/370, memory protection is provided through the use of keys. A key is a 4-bit quantity. Each 2-K block of memory has a key (the storage key) associated with it. The CPU also has a key (the ... Multiprogramming with a fixed number of processes $d$. Multiprogramming with a variable number of processes $e$. Paging $f$.Segmentation

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 10 views

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28

Galvin Edition 9 Exercise 8 Question 7 (Page No. 390)
Sharing segments among processes without requiring that they have the same segment number is possible in a dynamically linked segmentation system. a. Define a system that allows static linking and sharing of segments without requiring that ... a paging scheme that allows pages to be shared without requiring that the page numbers be the same.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 14 views

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29

Galvin Edition 9 Exercise 8 Question 6 (Page No. 390)
Describe a mechanism by which one segment could belong to the address space of two different processes.

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 7 views

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30

Galvin Edition 9 Exercise 8 Question 5 (Page No. 390)
What is the effect of allowing two entries in a page table to point to the same page frame in memory? Explain how this effect could be used to decrease the amount of time needed to copy a large amount of memory from one place to another. What effect would updating some byte on the one page have on the other page ?

asked Mar 21 in Operating System by akash.dinkar12 Boss (40.5k points) | 11 views

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