Operating Systems management techniques

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Resource Management[1]

An operating system must manage limited resources. There is intense and heavy competition for these limited resources, so HOW does an operating system manage to efficiently balance resources?

OS resource management techniques

Resource management is the dynamic allocation and de-allocation by an operating system of processor cores, memory pages, and various types of bandwidth to computations that compete for those resources. The objective is to allocate resources so as to optimize responsiveness subject to the finite resources available. [2]

Technique Description
scheduling The aim of CPU scheduling is to make the system efficient, fast and fair.[3] Scheduling is the method by which work is assigned to resources that complete the work.[4]. There are many different scheduling strategies. The main purposes of scheduling algorithms are to minimize resource starvation and to ensure fairness amongst the parties utilizing the resources[5] Different scheduling approaches are:
  • First Come First Serve(FCFS) Scheduling
  • Shortest-Job-First(SJF) Scheduling
  • Priority Scheduling
  • Round Robin(RR) Scheduling.
  • Multilevel feedback queue scheduling.


policies Given a particular task, policy refers to what needs to be done (i.e. activities to perform) and mechanism refers to how to do it (i.e. implementation to enforce policy).[6]. Put another way, the separation of mechanism and policy is a designProduce a plan, simulation or model. principle in computer science. It states that mechanisms (those parts of a system implementation that control the authorization of operations and the allocation of resources) should not dictate (or overly restrict) the policies according to which decisions are made about which operations to authorize, and which resources to allocate.[7] Please distinguishMake clear the differences between two or more concepts or items. between policy and mechanism. Policies are ways to choose which activities to perform. Mechanisms are the implementations that enforce policies.[8]
multitasking In computing, multitasking is a concept of performing multiple tasks (also known as processes) over a certain period of time by executing them concurrently.[9]. Multitasking operating systems allow more than one program to run at a time. They can support either preemptive multitasking, where the OS doles out time to applications (virtually all modern OSes) or cooperative multitasking, where the OS waits for the program to give back control (Windows 3.x, Mac OS 9 and earlier).[10]
virtual memory In computing, virtual memory (also virtual storage) is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory.[11]. This video is deliciously excellent: https://www.youtube.com/watch?time_continue=1&v=qlH4-oHnBb8
paging This is related to virtual memory. In computer operating systems, paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in main memory. In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages. Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory.[12]. For a deeper (and excellent) look at paging, please click here
interrupt In system programming, an interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing. The processor responds by suspending its current activities, saving its stateGive a specific name, value or other brief answer without explanation or calculation., and executing a function called an interrupt handler (or an interrupt service routine, ISR) to deal with the event. This interruption is temporary, and, after the interrupt handler finishes, the processor resumes normal activities. There are two types of interrupts: hardware interrupts and software interrupts. [13]. Basically, the processor has a set of interrupt wires which are connected to a bunch of devices. When one of the devices has something to say, it turns its interrupt wire on, which triggers the processor (without the help of any software) to pause the execution of current instructions and start running a handler function.[14]
polling Polling, or polled operation, in computer science, refers to actively sampling the status of an external device by a client program as a synchronous activity. [15].
  • A polling cycle is the time in which each element is monitored once. The optimal polling cycle will vary according to several factors, including the desired speed of response and the overhead (e.g., processor time and bandwidth) of the polling.
  • In roll call polling, the polling device or process queries each element on a listGive a sequence of brief answers with no explanation. in a fixed sequence. Because it waits for a response from each element, a timing mechanism is necessary to prevent lock-ups caused by non-responding elements. Roll call polling can be inefficient if the overhead for the polling messages is high, there are numerous elements to be polled in each polling cycle and only a few elements are active.
  • In hub polling, also referred to as token polling, each element polls the next element in some fixed sequence. This continues until the first element is reached, at which time the polling cycle starts all over again.[16]

Standards

  • OutlineGive a brief account. OS resource management techniques: scheduling, policies, multitasking, virtual memory, paging, interrupt, polling.
  • References