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2
votes
1answer
61 views

Is the memory usage of total languages deterministic?

I'm interested in the memory usage of various programming languages when implemented on actual hardware. I believe that a Turing-complete programming language has, in general, unknowable memory usage ...
-1
votes
0answers
30 views

Page Table Size

Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table? ok see... no. of page table entries(PTE) = ...
2
votes
1answer
82 views

Virtual Address and Physical Address Space

A machine has 48-bit virtual addresses and 32-bit physical addresses. Pages are 8K. How many entries are needed for a conventional page table ? The answer is 2^35 entries Why not (2^32) / (2^13) = ...
3
votes
1answer
50 views

Combining adjacent memory blocks

This is a conceptual issue that I am having in designing an algorithm for a memory allocator that works in conjunction with memory pooling. Free blocks are put on one of several free lists within the ...
3
votes
1answer
26 views

How can I calculate the effective bandwidth of a memory system?

I am currently doing my homework for my Computer Architecture class. One of the questions asks: A computer has a 64-bit data bus and 64-bit-wide memory blocks. The memory devices have an access ...
3
votes
0answers
25 views

How did MacLisp's garbage collector “run in the register set”?

Olin Shivers, ‘History of T’: Maclisp on the [PDP]-10 had used a mark&sweep GC (one version of which famously "ran in the register set," though that is another story) This implies, in my ...
3
votes
1answer
44 views

How ram is divided

when I write a program, in a Von Neumann architecture, how the ram will be divided to receive data and instructions? For example if I have 1 MB of ram, the addresses from 0 to 499.999 for data and ...
1
vote
1answer
59 views

What is the file system of ram?

As much I know about a memory and storing data there would always be a managing type feature in every memory which manages all the data and its location. So, what is the file system of a RAM. I also ...
-1
votes
1answer
71 views

In a $k$-way set associative cache,main memory block mapping in range?

In a $k$-way set associative cache, the cache is divided into $v$ sets, each of which consists of $k$ lines. The lines of a set are placed in sequence one after another. The lines in set $s$ are ...
1
vote
3answers
53 views

How are variables accessed in the correct order from the stack?

I'm learning about the stack but one thing I am unable to understand is how variables can be accessed in the correct order. So if I had a basic program calculating the sum of some user entered values ...
1
vote
1answer
32 views

What does x-bit binary number means?

What does x-bit binary number mean? for example: if x = 8 is 8-bit means: any number consists of 8 bits, like : 10101110 or it has another meaning??
2
votes
1answer
58 views

Best Fit Memory Allocation Algorithm Statistical Analysis

I've been reading book on Operating System, in which author writes : Somewhat surprisingly, it(Best fit) also results in more wasted memory than first fit or next fit because it tends to fill up ...
2
votes
1answer
22 views

Operating Systems TestAndSet instruction

I was reading operating systems concurrency control topics where I came across TestAndSet() intruction. I first referred this book. But it has got very less ...
2
votes
2answers
368 views

Is page size always equal to frame size?

I'm learning about paging. My book says that the logical addresses generated by the CPU are in the form |p|d|(page number, page offset) and the physical addresses ...
4
votes
0answers
46 views

How are weak references in a reference counted system implemented?

When reference counting is used for automatic memory management (e.g. Objective C or Swift), it is well know that “loops” give problems. E.g. ...
1
vote
2answers
213 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
44 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 ...
0
votes
4answers
164 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
55 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 ...
7
votes
1answer
73 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
165 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 ...
1
vote
1answer
256 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
32 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
votes
0answers
136 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
47 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
109 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
851 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
vote
0answers
62 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
103 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
26 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
75 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
409 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
86 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 ...
1
vote
2answers
67 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 ...
11
votes
5answers
499 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
648 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
89 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
212 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
48 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
212 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
60 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
94 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 ...
1
vote
2answers
156 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
89 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
97 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
300 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
223 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
2k 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?