Major Elements Of Memory Management

Operating Systems are complex pieces of software that are designed for powerful hardware, easily capable of running many programs at once, the prioritize hardware task requests known as ‘system calls’ and allocate them memory space or processing time as needed.

RAM (Random Accesses Memory): RAM is used by CPU when a computer is running to store the information that it needs to be used very quickly but it does not store any information permanently.

i) Memory : cache server (holds recently acesed web pages in its RAM, for spedier aces

Busy waiting is a technique in which a process repeatedly checks to see if a condition is true without getting the processor time. While a process is in its critical section, any other process that tries to enter its critical section must loop continuously to get the critical section. This will make the process eat CPU (usually). That is just busy for waiting the processor time.

3.8) Scheduler: Scheduler in an operating system selects the next process to be admitted into the system and next process to run. The three schedulers and their differences are as follows:-

Irregular Access memory is inside the PC which store the information and work with capacity memory to make lessen less and influence space for essential things to like record and documents in light of the fact that for individual protection.

1.13 The issue of resource utilization shows up in different forms in different types of operating systems. List what resources must be managed carefully in the following settings:

6.2) Preemptive scheduling allows a process to be invoked/disturbed in the middle of its execution by taking the CPU and assigning it to another process which is in queue where as in case of NonPreemptive scheduling, process will give up on CPU only when the current process is executed and finished.

Ans: -> Preemptive scheduling: It allows a process to be interrupting in the middle of Its execution, and takes the CPU away and allocate it to another

1. Consider a processor that supports virtual memory. It has a virtually indexed physically tagged cache, TLB, and page table in memory. Explain what happens in such a processor from the time the CPU generates a virtual address to the point where the referenced memory contents are available to the processor.

for the next time slot of a core can consume a lot of time in

Linux uses the virtual memory to free up private or anonymous pages used by a process. When a page is ‘taken off’ the physical memory, it is copied to the backing store, also sometimes named swap area. Linux uses the term ‘swapping’, which usually refers to swapping a whole process out from another, to describe ‘paging’, which is the swapping of the inactive pages of a process or processes.

This would mean programmers would have to edit their code every time they changed machines or added more memory (Lemley, 1999). Early computers had small amounts of RAM because storage technology was very expensive. Programmers had to store master copies of programs on a secondary storage system and pull pieces into RAM as needed. The process of deciding which pieces to pull and which parts of RAM to replace was called “overlaying” (Denning, 2012). “It was estimated that most programmers spent half to two-thirds of their time planning overlay sequences. A reliable method of automating it had potential to increase programmer productivity and reduce debugging by several fold” (Denning, 2012). Thus, the concept of virtual memory was born. This concept makes use of the computer’s hard drive when main memory runs out. However, the hard drive is significantly slower than RAM so we want to keep most of the program functioning in RAM thus specialized hardware and software is needed to give the illusion of unlimited available fast memory (Lemley, 1999). This hardware converts a “virtual” address to a physical address in memory. Aside from virtually increasing memory size, virtual memory also provided three additional benefits, “it isolated users from each other, it allowed dynamic relocation of program pieces within RAM, and it provided read – write access control to individual pieces” (Denning, 2012). It is for these

Memory management exists in programs and applications, hardware, and in the Operating System (OS). In the Operating System, the OS goes to the hard drive, finding the piece of file or specific memory blocks, and then copies it into the RAM. The CPU is then able to access it. The OS must find a location in the RAM where it is not being used by anything else when it copies it from the hard drive.

How does Linux memory manage? Linux has something called virtual memory where each process can have different memory mapping properties. Furthermore, the processes can be invisible from each other as well as memory is able to be moved and swapped. In terms of the kernel, when it comes to memory management, the Kernel Logical Address is where caches & stacks are held. The KLA is not swappable, which is why it can map to the main memory and be used as the actual physical addresses for the memory. Kernel Virtual Address returns a virtual address and is allocated 3Gbs of space as opposed to the KLA’s 1Gb of allotted space. In terms of user space: User Virtual Address allows for lazy allocation which is when the application asks the kernel for heap memory in order to perform some future operation (e.g. an array). It also allows for swapping which is beneficial in that a lot systems will not use it due the swapping time