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0
votes
1answer
30 views

Operating System Paging concept

I am quoting a paragraph from the book "Operating System Principles" by Galvin. Usually, each page-table entry is 4 bytes long, but that size can vary as well. A 32-bit entry can point to one of ...
1
vote
1answer
14 views

Role of the MMU in a Page Fault Swap

When a virtual memory address outside the range of loaded into physical RAM is referenced and a page fault occurs, does the Memory Management Unit rely on DMA (Direct Memory Access) to swap the ...
0
votes
1answer
40 views

Calculating cache memory based on LRU algorithm

Assuming i have 4 blocks of cache memory, Using the LRU (Least Recently Used) replacement algorithm on this following sequence of access to memory blocks: 1 2 3 4 5 2 5 4 1 5 2 3 : ...
0
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0answers
26 views

Roles of the Memory Management Unit

I know that the first instruction stored in BIOS is "mapped" to memory address 0, and that a signal on the reset pin to the microprocessor causes this instruction to be fetched, beginning the POST and ...
2
votes
0answers
39 views

Recent Garbage collection survey paper

Many years ago I read a GC survey paper that was updated every few years with advances; I tried to find such a paper today to point a questioner on Stackoverflow at. However all I can find is very ...
0
votes
1answer
51 views

How exactly MOV AX will load data from RAM?

Somewhere on Internet I read : Whenever word size is greater than memory cell size, then there is a need for accessing multiple memory cell Example: for 16 bit processor: MOV AX [2000] To transfer ...
5
votes
1answer
18 views

Can multiple tasks in an RTOS share one stack to save memory?

Many small embedded systems have a limited amount of RAM, 10k or less. I know you can run an RTOS on such systems, however, a realistic number of tasks in such a system is very low, mainly because ...
8
votes
1answer
19 views

Memory ballooning in the OS

Some hypervisors optimize memory usage using a method that is called ballooning (at least that's what KVM calls it), this method deduplicates memory between VMs and sets common pages to read-only with ...
6
votes
1answer
28 views

Writing a multitasking operating system for a processor without MMU

I've been thinking of writing a hobby operating system for some of the ARM processors. There are many popular single-board computers with ARM MPU, so I simply wanted to purchase one of those (choosing ...
2
votes
1answer
147 views

Practical Page-Replacement Algorithms

Could anyone suggest other page replacement algorithms that are applicable to the real world aside from FIFO, Second Chance (Clock), Enhanced Second Chance and Random?
1
vote
1answer
80 views

What's the difference between Clock and Second Chance Page-Replacement Algorithm?

I know that they both have reference bit, but I only understand the Second Chance but not the Clock Page-Replacement algorithm. could anyone help me understand?
2
votes
1answer
56 views

How, in hardware, MIPS can access a word in the middle of an address

This is am example of a RAM address in the MIPS architecture (32 bits) I can imagine the RAM as having 32 pins just to inform the RAM address I want to access, so I can access each of these words ...
1
vote
2answers
65 views

How exactly the “load word” instruction loads from RAM?

PS: MIPS architecture This is a model of a memory RAM of 4GB: it has 4,294,967,295 addresses, and each address has 32 bits. Can somebody tell me why the load word instruction needs an offset to the ...
2
votes
1answer
93 views

How does the OS know the physical address of a process' first memory page?

If I have a program, its instructions are stored on the hard drive. When I double-click the executable the pages of memory for this process must get loaded in to RAM. However, for the pages to get ...
0
votes
1answer
50 views

How is heap memory allocated to a process?

I want to better understand how OS provides heap memory to a process. Here by heap memory I mean the memory allocated dynamically, say by call to malloc. When a ...
0
votes
1answer
28 views

In Pagination, how does the S.O. knows where the page is in secondary Memory?

So every process has its own Page Table, the page table references the frame where the page is in physical memory and also has a valid-invalid bit that tells whether it is in physical memory or in ...
3
votes
1answer
49 views

Session Memory in the Windows Kernel

While reading the paper Effective Data-Race Detection for the Kernel by John Erickson and Madanlal Musuvathi. I was stuck on a slightly tricky sentence. "Similarly, a range of kernel-address space, ...
2
votes
1answer
54 views

Maximum amount of memory that can be allocated to a process

DISCLAIMER: The following scenario was taken from an assignment I got in a OS course I'm taking, and it arose a lot of question marks in my head. However non of the questions asked by myself here ...
2
votes
2answers
73 views

How to filter a very, very large file

I have a very large unsorted file, 1000GB, of ID pairs ID:ABC123 ID:ABC124 ID:ABC123 ID:ABC124 ID:ABC123 ID:ABA122 ID:ABC124 ID:ABC123 ID:ABC124 ID:ABC126 I would like to filter the file for ...
0
votes
0answers
175 views

size of memory in 64-bit computer system

I'm new here, a brief intro, I'm a student majoring in comp-sci. Right now I'm having a bit confusion to answer one of my assignment, it is about system paging. I want to know how do I able to know ...
2
votes
3answers
59 views

Does exploiting a spatial Locality in Cache always leads to a lower miss rate?

I've read that, incorporating many words(spatial locality) per cache blocks leads to lower miss rate. Is it the case always? One possibility of such approach is to make a single cache block of size ...
0
votes
0answers
33 views

Implementing/approximating Belady's OPT for multithreaded environments (papers?)

I have the memory reference string for a multithreaded application and want to run this through a simulator which implements/approximates Belady's OPT page replacement algorithm. But what is the best ...
9
votes
2answers
112 views

Are there any garbage collectors that take into account paging?

Garbage collections have to visit all objects that are alive, so as to find the memory that can be reclaimed. (Having many generations’ just delays this a bit) All things being equal, it is ...
1
vote
1answer
22 views

What memory locations will the CPU fetch instructions from with instruction length of 16bits

While reading Stallings OS Internals and Design, I run into problem. Here is example from the book. For example, consider a simplified computer in which each instruction occupies one 16-bit word ...
1
vote
1answer
36 views

Qubits Related to RAM?

I read in this article that the amount of bits that can be emulated by a certain number of qubits is 2^(number of qubits). This is because each qubit can be in one of 2 states after it collapses, and ...
2
votes
2answers
86 views

Which part of the computer allocates memory in RAM?

When we declare a variable there will be a random part of memory will be allocated in RAM. Which component will allocate the memory? Is the processor or any other specific hardware doing the ...
0
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0answers
15 views

Instruction Set Architecture- Question [duplicate]

So this is a homework question but I have some solution and I am just confused, so a detailed example or help would be nice. You are designing the instruction set for a new type of computer. The ...
-1
votes
1answer
287 views

Instruction Set Architecture (ISA) design

Yes, this is a homework question, I've tried working it out and was hoping I could get pointed in the right direction. Here's the question: You are designing the instruction set for a new type of ...
2
votes
1answer
1k views

Word- or byte-addressable? Correct terminology

Seemingly, a byte has established itself to be 8bit (is that correct?). RAM and NOR-flash can be normally accessed on a quite granular level, but it is up to the system architecture to determine if ...
-1
votes
1answer
111 views

Does virtual address space resides in virtual memory?

I have several confusion like : Does virtual address space resides in virtual memory ? Does each process has its own virtual address space like each process has its own virtual memory and own page ...
-1
votes
1answer
71 views
0
votes
1answer
254 views

Size of address registers and data registers in relation with memory size

Suppose that a processor can address directly up to 4 Gigabyte main memory and can operate words with size 32 bit. Find how big should be the size of the "MAR" (memory address registers), "MDR" ...
0
votes
0answers
209 views

What determines a hit/miss with cache memory?

I was taught that when a reference is mapped to a cache block, X, for the first time, the word is stored in the cache block, bearing a tag and index that helps identify it for future reads. Then, ...
2
votes
2answers
347 views

What is “memory coalescing”?

I came to know that the graphic processing unit have something called memory coalescing. On reading on it I was not clear on the topic. Is this any way related to Memory Level Parallelism. I have ...
-1
votes
1answer
70 views

processes response time confusion

An OS contains 10 identical processes that were initiated at the same time.Each process contains 15 identical requests. Each request consume 20 msec of CPU time.A request is followed by an I/O ...
0
votes
1answer
866 views

Understanding the basic concepts in memory organisation

(Before actually proceeding to the question, I want to confess that this is a homework question, please do consider it and help me in improving my understanding a bit more.) I have recently started ...
4
votes
3answers
287 views

What does “deterministic” mean in the context of memory management?

At the time of writing, Wikipedia describes determinism as: "a deterministic algorithm is an algorithm which, given a particular input, will always produce the same output, with the underlying ...
3
votes
2answers
55 views

What does “prompt collection” mean in the context of memory management?

I often see people assert that reference counting techniques such as shared_ptr in C++ provide prompt collection (e.g. here and here) but I am not sure what exactly ...
1
vote
0answers
68 views

Drawing the Design of an SRAM chip

I have come across a question that I am having quite a hard time with. I am to draw a design of an SRAM chip with an organization of 2M*128 SRAM that uses 1K*1K arrays of D latches. And then the ...
1
vote
0answers
635 views

want to know concept behing Multilevel paging

In order to use large size page table hierarchical paging is done . In case of two level page table scheme . for : logical address space - 32bit - $2^32$ page size - 4kb i.e $2^12$ It is mentioned ...
4
votes
1answer
445 views

Despite it is so important, why don't computer science departments offer a class named “memory management”? [closed]

I don't understand why computer science departments don't offer a class named memory management? I see that most of the problems encountered in computer science are about memory management concepts. ...
1
vote
1answer
101 views

How a program is copied to RAM from harddisk

I know that for executing a program, it should be copied to RAM. But the problem is whole of it may not be copied always. Since the size of the RAM is limited, there is mechanism called virtual ...
1
vote
1answer
1k views

Hierarchical Paging

Suppose I have a system with 32-bit logical and 16-bit physical address spaces, and the page size is 512 bytes. For simplicity, ignore the valid/invalid bits in the page table. How many sections will ...
1
vote
2answers
979 views

Given the logical address, how to extract the page number?

I am studying Computer Systems. I have th following question and its answer: Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page number? ...
3
votes
1answer
2k views

What is the difference between a 'page' or memory and a 'frame' of memory?

WP has a adequate discussion of paging, which I think I understand.. However I am confused by the articles repeated use of the term Page Frame. I thought frames and pages were different things. ...
0
votes
1answer
63 views

How Does Dynamic Heap Storage Have Something to Do with Heap?

There are three typical ways to allocate memory for programs: static, stack and dynamic heap. However, when I look at the implementation of dynamic heap memory allocation from wikipedia , what I found ...
0
votes
2answers
7k views

How to work out physical address corresponding to logical address?

I am looking to calculate the physical address corresponding to a logical address in a paging memory management scheme. I just want to make sure I am getting the calculation right, as I fear I could ...
2
votes
2answers
342 views

Handling untrusted string input in printf in C [closed]

I stumbled upon the MSDN Best Practices for Code Review. Under the section “Untrusted Inputs”, I found following which I didn't understand properly. Why is the following considered safe? ...
2
votes
1answer
243 views

Processes and Segmentation

The following problem was on my final and in Gate 2006, but I don't understand how to solve it: Different methods of memory management have different overheads: ...
1
vote
2answers
2k views

How does increasing the page size affect the number of page faults?

If we let the physical memory size remain constant, What effect does the size of the page have on the number of frames? What effect does the number of frames have on the number of page faults? ...