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0
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1answer
19 views

How to calculate the size of a page in a two level paging CPU?

I am having difficulties with understanding the concept of paging. As a result I've got no idea how I can solve the following exercise - I'm lacking one more equation to solve it. I've read a lot ...
2
votes
0answers
16 views

How does the Spark M7 “Concurrent Fine-grain Memory Migration” benefit a garbage collector?

Sun has been making a lot of noise about the Spark M7 and its inbuilt support for the java garbage collector. However there seem to be very little easy to find information about it. Please can ...
-1
votes
4answers
87 views

Can only information(data) be stored in ram?

Basic question, but is only information/ data stored in ram? Are computer files such as a word file considered information/ data? This is one of the questions in a summer assignment for ap computer ...
-2
votes
1answer
27 views

How does the operating system set up memory boundaries? [closed]

Is there a hardware interrupt that is pre-configured by the OS or something? Try to keep the answer on the scale of a register or so. Are some special preparatory signals sent across the bridges ...
-1
votes
0answers
17 views

How does the OS regulate CPU permissions? [duplicate]

How does the operating system limit the instruction set of the CPU to other processes? I know that it'd take forever for the loader to parse out the executable code, so is there are hardware ...
7
votes
1answer
59 views

Page management in OS kernels

I looked at some old OS theory books of mine and noticed that one glaring omission in all of these OS books is how to actually keep track of physical pages that are free (i.e. algorithms for actually ...
5
votes
3answers
150 views

Data types for storing arbitrarily much information

I've heard that YouTube had a problem with the view count on Gangnam style since the number of views exceeded the variable byte size. What's the problem with creating really large variables? Why ...
0
votes
1answer
85 views

How do binary trees use memory to store its data?

So I know that arrays use a block on contiguous memory addresses to store data to memory, and lists (not linked lists) make use of static arrays and when data is appended to the list, if there is no ...
0
votes
0answers
31 views

Is this cache entry a hit or a miss? [duplicate]

The Problem: A CPU produces the following sequence of read addresses in hex. Suppose the cache is empty to begin with and assuming an LRU replacement, determine whether each address produces a hit or ...
0
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0answers
79 views

What happens if the associativity level is greater than the cache size?

I am working on a computer organization caching problem The Problem: What happens if the associativity level is greater than the cache size? I know that associativity level is how many blocks are ...
2
votes
0answers
40 views

When there's no memory, should malloc or read/write fail?

To my surprise, I recently found out that Windows would fail a large memory allocation even if little of said memory is to actually be used, e.g. even if you don't want the swap, you better not ...
2
votes
2answers
69 views

where is all deleted data will go from memory system/internet? [closed]

where is all deleted data will go from a memory system ? if it is not deleting actually where it storing ? i am always wonder about this when we are sending something to a memory system it takes ...
-2
votes
1answer
158 views

Size of address spaces (logical and physical)

Suppose a system in which addresses (physical and logical) occupy 32 bits, page size is 1024 bytes (210), and physical memory is of size 32MB. How many frames are in physical memory? Is the logical ...
1
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0answers
41 views

Clock variant of the Second-Chance page-replacement Algorithm vs. standard Second-Chance Algorithm

A sample question for my upcoming Operating Systems exam is: Under which circumstances would the clock variant [of the second-chance algorithm] be preferred over the standard second-chance ...
16
votes
4answers
3k views

How do garbage collectors avoid stack overflow?

So I was thinking about how garbage collectors work and I thought of an interesting issue. Presumably garbage collectors have to traverse all structures in the same way. They can't know weather they ...
0
votes
1answer
49 views

How does cpu fetch active program data (using virtual address) from storage when there is a page fault?

I read that cpu generates virtual address and using the same mmu translates to physical address and then fetches the data from RAM. But when there is a page fault, the data is fetched from the HDD(or ...
0
votes
0answers
20 views

How to find maximum size user-space main memory that can be supported?

I can't figure out how to find maximum size of user space main memory. I have this data: 64-bit computer system that uses pure paging with 16KB page size, if each page table entry is 4 bytes ...
3
votes
1answer
69 views

When was the terminology *tracing collector* introduced to denote both mark-and-sweep and copy collectors

Automatic storage reclamation, aka garbage collection, comes in two main families, sometimes cooperating: the reference count collectors and the tracing collectors. I may develop specifics of each ...
2
votes
5answers
269 views

How can a CPU access more memory locations than 2^wordsize?

I noticed that CPU's like the 8086 and especially the 8080 have the ability to access more memory than what one would normally assume. The 8080, for example, has an 8-bit word size but can use a ...
0
votes
1answer
80 views

Binary digit problem?

Question: If a system has $32k$ bytes and each such byte has unique address(so $32k$ addresses), what is the smallest possible bits that can be use by every byte for the address ? All the bytes ...
0
votes
1answer
40 views

Can this question be solved without knowing the Page Table Entry?

I'm preparing for the exams and this question came up - Consider a machine with $64MB$ physical memory and a $32$-bit virtual address space. If the page size is $4KB$, what is the approximate size ...
10
votes
5answers
368 views

Why is the object destructor paradigm in garbage collected languages pervasively absent?

Looking for insight into decisions around garbage collected language design. Perhaps a language expert could enlighten me? I come from a C++ background, so this area is baffling to me. It seems ...
0
votes
1answer
171 views

Size of framebuffer lookup table [closed]

If the frame buffer has 8 bits per pixel and 8 bits are allocated for each of the R, G, B components, what would be the size of the lookup table? a) 24 bytes b) 1024 bytes ...
-2
votes
1answer
19 views

Why we need tagbits when we already have indexbit and offset?

I was watching a lecture and got confused at one point when professor said that to distinguish between two addresses having same values of offset as well as index bit we need tag.Why we need tag ? for ...
3
votes
1answer
60 views

Best design of a software controlled page table: to echo the TLB?

I am building some simple system software for the Microblaze FPGA (actually being run on OVPsim at least for now). The system is to experiment with various memory management regimes. The first ...
0
votes
2answers
161 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
32 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
146 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
votes
0answers
41 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 ...
3
votes
1answer
84 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
96 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
63 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 ...
9
votes
1answer
65 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
202 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
205 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
1k 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?
3
votes
1answer
199 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
182 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
261 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 ...
6
votes
1answer
107 views

Tag-free garbage collection for object oriented languages

I'm looking around for a good garbage collection technique for my language and found this paper, where Benjamin Goldberg describes a garbage collection technique for strongly typed languages, which ...
0
votes
1answer
65 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
37 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
84 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
80 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
143 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
413 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 of confusion to answer one of my assignments, it is about system paging. I want to know how am I able to ...
2
votes
3answers
122 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 ...
10
votes
2answers
168 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
29 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
43 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 ...