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64-487: Some scenarios associate this kind of planning with learning life skills . Schedules are necessary, or at least useful, in situations where individuals need to know what time they must be at a specific location to receive a specific service, and where people need to accomplish a set of goals within a set time. Schedules can usefully span both short periods, such as a daily or weekly schedule, and long-term planning for periods of several months or years. They are often made using

128-469: A Workload Manager feature to the scheduler, which schedules processor resources according to an elaborate scheme defined by the installation. Very early MS-DOS and Microsoft Windows systems were non-multitasking, and as such did not feature a scheduler. Windows 3.1x used a non-preemptive scheduler, meaning that it did not interrupt programs. It relied on the program to end or tell the OS that it didn't need

192-562: A calendar , where the person making the schedule can note the dates and times at which various events are planned to occur. Schedules that do not set forth specific times for events to occur may instead list algorithmically an expected order in which events either can or must take place. In some situations, schedules can be uncertain, such as where the conduct of daily life relies on environmental factors outside human control. People who are vacationing or otherwise seeking to reduce stress and achieve relaxation may intentionally avoid having

256-484: A domino effect that can negatively impact the entire area's transportation planning. In an educational institution, a timetable must be established that refers students and teachers to classrooms each hour. The challenge of constructing this schedule for larger institutions was addressed by Gunther Schmidt and Thomas Ströhlein in 1976. They formalized the timetable construction problem, and indicated an iterative process using logical matrices and hypergraphs to obtain

320-512: A free content work. Licensed under CC BY-SA 3.0 IGO. Text taken from Pathways of progression: linking technical and vocational education and training with post-secondary education​ , UNESCO, UNESCO. UNESCO. World Health Organization. Division of Mental Health (1993), Life skills education for children and adolescents in schools , hdl : 10665/63552 , Wikidata   Q114785254 , retrieved 2022-10-21 Scheduling (computing) In computing , scheduling

384-520: A multilevel feedback queue with priority levels ranging from 0 to 140 was used; 0–99 are reserved for real-time tasks and 100–140 are considered nice task levels. For real-time tasks, the time quantum for switching processes was approximately 200 ms, and for nice tasks approximately 10 ms. The scheduler ran through the run queue of all ready processes, letting the highest priority processes go first and run through their time slices, after which they will be placed in an expired queue. When

448-432: A common division is made between foreground (interactive) processes and background (batch) processes. These two types of processes have different response-time requirements and so may have different scheduling needs. It is very useful for shared memory problems. A work-conserving scheduler is a scheduler that always tries to keep the scheduled resources busy, if there are submitted jobs ready to be scheduled. In contrast,

512-412: A formal schedule will often be created as an initial step in carrying out a specific project, such as the construction of a building, development of a product, or launch of a program. Establishing a project management schedule involves listing milestones, activities, and deliverables with intended start and finish dates, of which the scheduling of employees may be an element. A production process schedule

576-578: A lighter load on the system if converted to a multithreaded structure. AIX 5 implements the following scheduling policies: FIFO, round robin, and a fair round robin. The FIFO policy has three different implementations: FIFO, FIFO2, and FIFO3. The round robin policy is named SCHED_RR in AIX, and the fair round robin is called SCHED_OTHER. Linux 1.2 used a round-robin scheduling policy. Linux 2.2 added scheduling classes and support for symmetric multiprocessing (SMP). In Linux 2.4, an O(n) scheduler with

640-435: A network and managed through an administrative back end. The scheduler is an operating system module that selects the next jobs to be admitted into the system and the next process to run. Operating systems may feature up to three distinct scheduler types: a long-term scheduler (also known as an admission scheduler or high-level scheduler), a mid-term or medium-term scheduler , and a short-term scheduler . The names suggest

704-425: A non-work conserving scheduler is a scheduler that, in some cases, may leave the scheduled resources idle despite the presence of jobs ready to be scheduled. There are several scheduling problems in which the goal is to decide which job goes to which station at what time, such that the total makespan is minimized: A very common method in embedded systems is to schedule jobs manually. This can for example be done in

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768-522: A preemptive scheduling algorithm. All Process Manager processes run within a special multiprocessing task, called the blue task . Those processes are scheduled cooperatively, using a round-robin scheduling algorithm; a process yields control of the processor to another process by explicitly calling a blocking function such as WaitNextEvent . Each process has its own copy of the Thread Manager that schedules that process's threads cooperatively;

832-441: A process that has a low priority, a process that is page faulting frequently, or a process that is taking up a large amount of memory in order to free up main memory for other processes, swapping the process back in later when more memory is available, or when the process has been unblocked and is no longer waiting for a resource. In many systems today (those that support mapping virtual address space to secondary storage other than

896-411: A product of synthesis: many skills are developed simultaneously through practice, like humor , which allows a person to feel in control of a situation and make it more manageable in perspective. It allows the person to release fears, anger, and stress & achieve a qualitative life. For example, decision-making often involves critical thinking ("what are my options?") and values clarification ("what

960-420: A schedule for a certain period of time. Certain kinds of schedules reflect information that is generally made available to the public, so that members of the public can plan certain activities around them. These may include things like: An internal schedule is a schedule that is only of importance to the people who must directly abide by it. It has been noted that "groups often begin with a schedule imposed from

1024-465: A scheduler will implement a suitable compromise. Preference is measured by any one of the concerns mentioned above, depending upon the user's needs and objectives. In real-time environments, such as embedded systems for automatic control in industry (for example robotics ), the scheduler also must ensure that processes can meet deadlines ; this is crucial for keeping the system stable. Scheduled tasks can also be distributed to remote devices across

1088-532: A solution. Life skills Life skills are abilities for adaptive and positive behavior that enable humans to deal effectively with the demands and challenges of life. This concept is also termed as psychosocial competency. The subject varies greatly depending on social norms and community expectations but skills that function for well-being and aid individuals to develop into active and productive members of their communities are considered as life skills. The UNICEF Evaluation Office suggests that "there

1152-538: A specific skill. Parenting itself can be considered as a set of life skills which can be taught or comes natural to a person. Educating a person in skills for dealing with pregnancy and parenting can also coincide with additional life skills development for the child and enable the parents to guide their children in adulthood. Many life skills programs are offered when traditional family structures and healthy relationships have broken down, whether due to parental lapses, divorce, psychological disorders or due to issues with

1216-411: A target quality-of-service . Scheduling is fundamental to computation itself, and an intrinsic part of the execution model of a computer system; the concept of scheduling makes it possible to have computer multitasking with a single central processing unit (CPU). A scheduler may aim at one or more goals, for example: In practice, these goals often conflict (e.g. throughput versus latency), thus

1280-759: A thread yields control of the processor to another thread by calling YieldToAnyThread or YieldToThread . macOS uses a multilevel feedback queue, with four priority bands for threads – normal, system high priority, kernel mode only, and real-time. Threads are scheduled preemptively; macOS also supports cooperatively scheduled threads in its implementation of the Thread Manager in Carbon . In AIX Version 4 there are three possible values for thread scheduling policy: Threads are primarily of interest for applications that currently consist of several asynchronous processes. These applications might impose

1344-451: A time-multiplexed fashion. Sometimes the kernel is divided in three or more parts: Manual scheduling, preemptive and interrupt level. Exact methods for scheduling jobs are often proprietary. When designing an operating system, a programmer must consider which scheduling algorithm will perform best for the use the system is going to see. There is no universal best scheduling algorithm, and many operating systems use extended or combinations of

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1408-431: A truck before loading materials on the truck (since nothing can be loaded until the truck is available for things to be loaded on). Scheduling of projects, therefore, requires the identification of all of the tasks necessary to complete the project, and the earliest time at which each task can be completed. In creating a schedule, a certain amount of time is usually set aside as a contingency against unforeseen days. This time

1472-410: A wide range of skills development opportunities attuned to national and local contexts. Learning to learn and the development of literacy and numeracy skills, transversal skills and citizenship skills are integral components of TVET. Life skills are often taught in the domain of parenting , either indirectly through the observation and experience of the child, or directly with the purpose of teaching

1536-399: Is a workplace schedule , which lists the hours that specific employees are expected to be in a workplace, ensure sufficient staffing at all times while in some instances avoiding overstaffing. A work schedule for a business that is open to the public must correspond to the hours of operation of the business, so that employees are available at times when customers are able to use the services of

1600-427: Is called scheduling variance, or float , and is a core concept for the critical path method . Scheduling is important as an internal process in computer science , wherein a database transaction schedule is a list of actions from a set of transactions in databases, and scheduling is the way various processes are assigned in computer multitasking and multiprocessing operating system design. This kind of scheduling

1664-493: Is capable of forcibly removing processes from a CPU when it decides to allocate that CPU to another process, or non-preemptive (also known as voluntary or co-operative ), in which case the scheduler is unable to force processes off the CPU. A preemptive scheduler relies upon a programmable interval timer which invokes an interrupt handler that runs in kernel mode and implements the scheduling function. Another component that

1728-576: Is concerned with scheduling a number of employees with typical constraints such as rotation of shifts, limits on overtime, etc. The travelling salesman problem is concerned with scheduling a series of journeys to minimize time or distance. Some of these problems may be solved efficiently with linear programming , but many scheduling problems require integer variables. Although efficient algorithms exist to give integer solutions in some situations (see network flow models), most problems that require integer solutions cannot yet be solved efficiently. Scheduling

1792-413: Is desirable to schedule the usage of wireless resources as efficiently as possible, while maximizing the overall network performance. The scheduling of resources, usually subject to constraints, is the subject of several problems that are in the area of research known as operations research , usually in terms of finding an optimal solution or method for solving. For example, the nurse scheduling problem

1856-447: Is given equal time (for instance 1 ms, usually between 1 ms and 100 ms) in a cycling list. So, process A executes for 1 ms, then process B, then process C, then back to process A. More advanced algorithms take into account process priority, or the importance of the process. This allows some processes to use more time than other processes. The kernel always uses whatever resources it needs to ensure proper functioning of

1920-466: Is important that a long-term scheduler selects a good process mix of I/O-bound and CPU-bound processes. If all processes are I/O-bound, the ready queue will almost always be empty, and the short-term scheduler will have little to do. On the other hand, if all processes are CPU-bound, the I/O waiting queue will almost always be empty, devices will go unused, and again the system will be unbalanced. The system with

1984-425: Is important to me?"), ("How do I feel about this?"). Ultimately, the interplay between the skills is what produces powerful behavioral outcomes, especially where this approach is supported by other strategies. Life skills can vary from financial literacy , through substance-abuse prevention , to therapeutic techniques to deal with disabilities such as autism . The World Health Organization in 1999 identified

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2048-581: Is incorporated into the computer program, and the user may be completely unaware of what tasks are being carried out and when. Scheduling operations and issues in computing may include: Wireless networks should have a flexible service architecture to integrate different types of services on a single air-interface because terminals have different service requirements. On top of the flexible service architecture, effective quality of service (QoS) management schemes are also needed. Therefore, wireless resources need to be shared among all terminals carefully and it

2112-465: Is involved in the CPU-scheduling function is the dispatcher, which is the module that gives control of the CPU to the process selected by the short-term scheduler. It receives control in kernel mode as the result of an interrupt or system call. The functions of a dispatcher involve the following: The dispatcher should be as fast as possible since it is invoked during every process switch. During

2176-498: Is no definitive list" of psychosocial skills; nevertheless UNICEF enumerates psychosocial and interpersonal skills that are generally well-being oriented, and essential alongside literacy and numeracy skills. Since it changes its meaning from culture to culture and life positions, it is considered a concept that is elastic in nature. But UNICEF acknowledges social and emotional life skills identified by Collaborative for Academic, Social and Emotional Learning (CASEL). Life skills are

2240-462: Is offered, as opposed to best-effort communication, weighted fair queuing may be utilized. In advanced packet radio wireless networks such as HSDPA (High-Speed Downlink Packet Access) 3.5G cellular system, channel-dependent scheduling may be used to take advantage of channel state information . If the channel conditions are favourable, the throughput and system spectral efficiency may be increased. In even more advanced systems such as LTE ,

2304-468: Is often required to prevent them from blocking due to waiting on each other. In these cases, special-purpose job scheduler software is typically used to assist these functions, in addition to any underlying admission scheduling support in the operating system. Some operating systems only allow new tasks to be added if it is sure all real-time deadlines can still be met. The specific heuristic algorithm used by an operating system to accept or reject new tasks

2368-562: Is reserved for the Operating System. User interfaces and APIs work with priority classes for the process and the threads in the process, which are then combined by the system into the absolute priority level. The kernel may change the priority level of a thread depending on its I/O and CPU usage and whether it is interactive (i.e. accepts and responds to input from humans), raising the priority of interactive and I/O bounded processes and lowering that of CPU bound processes, to increase

2432-414: Is the admission control mechanism . The medium-term scheduler temporarily removes processes from main memory and places them in secondary memory (such as a hard disk drive ) or vice versa, which is commonly referred to as swapping out or swapping in (also incorrectly as paging out or paging in ). The medium-term scheduler may decide to swap out a process that has not been active for some time,

2496-442: Is the action of assigning resources to perform tasks . The resources may be processors , network links or expansion cards . The tasks may be threads , processes or data flows . The scheduling activity is carried out by a mechanism called a scheduler . Schedulers are often designed so as to keep all computer resources busy (as in load balancing ), allow multiple users to share system resources effectively, or to achieve

2560-435: Is to be executed (allocated a CPU) after a clock interrupt , an I/O interrupt, an operating system call or another form of signal . Thus the short-term scheduler makes scheduling decisions much more frequently than the long-term or mid-term schedulers – A scheduling decision will at a minimum have to be made after every time slice, and these are very short. This scheduler can be preemptive , implying that it

2624-410: Is used for the planning of the production or the operation, while a resource schedule aids in the logistical planning for sharing resources among several entities. In such cases, a schedule "is obtained by estimating the duration of each task and noting any dependencies amongst those tasks". Dependencies , in turn, are tasks that must be completed in order to make other tasks possible, such as renting

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2688-541: Is useful in transportation planning . The important components of transportation improvement proposals include (a) comprehensive evaluations of the scope of work to be completed, (b) reasonably accurate cost estimates for finishing the task, and (c) a feasible project schedule. If any of these factors are not accurately defined, then there is a strong possibility of unexpected difficulties. Poor scoping and/or scheduling may result in serious budget problems, delays and cancellations of transportation improvements, and sometimes even

2752-802: The Family and Youth Services Bureau, a division of the U.S. Department of Health and Human Services advocates the theory of positive youth development (PYD) as a replacement for the less effective prevention programs. PYD focuses on the strengths of an individual as opposed to the older decrepit models which tend to focus on the "potential" weaknesses that have yet to be shown. "..life skills education, have found to be an effective psychosocial intervention strategy for promoting positive social, and mental health of adolescents which plays an important role in all aspects such as strengthening coping strategies and developing self-confidence and emotional intelligence..." [REDACTED]  This article incorporates text from

2816-448: The best performance will thus have a combination of CPU-bound and I/O-bound processes. In modern operating systems, this is used to make sure that real-time processes get enough CPU time to finish their tasks. Long-term scheduling is also important in large-scale systems such as batch processing systems, computer clusters , supercomputers , and render farms . For example, in concurrent systems , coscheduling of interacting processes

2880-430: The business. One common method of scheduling employees to ensure the availability of appropriate resources is a Gantt chart . Another example of an internal schedule is the class schedule of an individual student, indicating what days and times their classes will be held. A schedule may also involve the completion of a project with which the public has no interaction public prior to its completion. In project management ,

2944-567: The children (such as substance abuse or other risky behavior). For example, the International Labour Organization is teaching life skills to ex-child laborers and at-risk children in Indonesia to help them avoid and to recover from worst forms of child abuse . While certain life skills programs focus on teaching the prevention of certain behaviors, they can be relatively ineffective. Based upon their research,

3008-815: The context switches, the processor is virtually idle for a fraction of time, thus unnecessary context switches should be avoided. The time it takes for the dispatcher to stop one process and start another is known as the dispatch latency . A scheduling discipline (also called scheduling policy or scheduling algorithm ) is an algorithm used for distributing resources among parties which simultaneously and asynchronously request them. Scheduling disciplines are used in routers (to handle packet traffic) as well as in operating systems (to share CPU time among both threads and processes ), disk drives ( I/O scheduling ), printers ( print spooler ), most embedded systems, etc. The main purposes of scheduling algorithms are to minimize resource starvation and to ensure fairness amongst

3072-493: The following core cross-cultural areas of life skills: UNICEF listed similar skills and related categories in its 2012 report. Life skills curricular designed for K-12 often emphasize communications and practical skills needed for successful independent living as well as for developmental-disabilities/special-education students with an Individualized Education Program (IEP). There are various courses being run based on WHO's list supported by UNFPA. In Madhya Pradesh, India,

3136-419: The high-priority threads and FIFO among the lower-priority ones. In this sense, response time is short for most threads, and short but critical system threads get completed very quickly. Since threads can only use one time unit of the round-robin in the highest-priority queue, starvation can be a problem for longer high-priority threads. The algorithm used may be as simple as round-robin in which each process

3200-405: The next to be scheduled for execution. Similar to shortest job first (SJF). With this strategy the scheduler arranges processes with the least estimated processing time remaining to be next in the queue. This requires advanced knowledge or estimations about the time required for a process to complete. The operating system assigns a fixed-priority rank to every process, and the scheduler arranges

3264-409: The outside, but effective groups also develop an internal schedule that sets goals for the completion of micro-tasks". Unlike schedules for public events or publicly available amenities, there is no need to go to the time and effort of publicizing the internal schedule. To the contrary, an internal schedule may be kept confidential as a matter of security or propriety. An example of an internal schedule

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3328-674: The parties utilizing the resources. Scheduling deals with the problem of deciding which of the outstanding requests is to be allocated resources. There are many different scheduling algorithms. In this section, we introduce several of them. In packet-switched computer networks and other statistical multiplexing , the notion of a scheduling algorithm is used as an alternative to first-come first-served queuing of data packets. The simplest best-effort scheduling algorithms are round-robin , fair queuing (a max-min fair scheduling algorithm), proportional-fair scheduling and maximum throughput . If differentiated or guaranteed quality of service

3392-462: The processes in the ready queue in order of their priority. Lower-priority processes get interrupted by incoming higher-priority processes. The scheduler assigns a fixed time unit per process, and cycles through them. If process completes within that time-slice it gets terminated otherwise it is rescheduled after giving a chance to all other processes. This is used for situations in which processes are easily divided into different groups. For example,

3456-523: The processor so that it could move on to another process. This is usually called cooperative multitasking. Windows 95 introduced a rudimentary preemptive scheduler; however, for legacy support opted to let 16-bit applications run without preemption. Windows NT -based operating systems use a multilevel feedback queue. 32 priority levels are defined, 0 through to 31, with priorities 0 through 15 being normal priorities and priorities 16 through 31 being soft real-time priorities, requiring privileges to assign. 0

3520-572: The programme is being run with Government to teach these through Government Schools. Skills for work and life, known as technical and vocational education and training (TVET) is comprising education, training and skills development relating to a wide range of occupational fields, production, services and livelihoods. TVET, as part of lifelong learning , can take place at secondary , post-secondary and tertiary levels , and includes work-based learning and continuing training and professional development which may lead to qualifications. TVET also includes

3584-422: The ready queue (in main memory); that is, when an attempt is made to execute a program, its admission to the set of currently executing processes is either authorized or delayed by the long-term scheduler. Thus, this scheduler dictates what processes are to run on a system, the degree of concurrency to be supported at any one time – whether many or few processes are to be executed concurrently, and how

3648-434: The ready queue. This is commonly used for a task queue , for example as illustrated in this section. Earliest deadline first (EDF) or least time to go is a dynamic scheduling algorithm used in real-time operating systems to place processes in a priority queue. Whenever a scheduling event occurs (a task finishes, new task is released, etc.), the queue will be searched for the process closest to its deadline, which will be

3712-662: The relative frequency with which their functions are performed. The process scheduler is a part of the operating system that decides which process runs at a certain point in time. It usually has the ability to pause a running process, move it to the back of the running queue and start a new process; such a scheduler is known as a preemptive scheduler , otherwise it is a cooperative scheduler . We distinguish between long-term scheduling , medium-term scheduling , and short-term scheduling based on how often decisions must be made. The long-term scheduler , or admission scheduler , decides which jobs or processes are to be admitted to

3776-719: The responsiveness of interactive applications. The scheduler was modified in Windows Vista to use the cycle counter register of modern processors to keep track of exactly how many CPU cycles a thread has executed, rather than just using an interval-timer interrupt routine. Vista also uses a priority scheduler for the I/O queue so that disk defragmenters and other such programs do not interfere with foreground operations. Mac OS 9 uses cooperative scheduling for threads, where one process controls multiple cooperative threads, and also provides preemptive scheduling for multiprocessing tasks. The kernel schedules multiprocessing tasks using

3840-457: The scheduling algorithms above. For example, Windows NT /XP/Vista uses a multilevel feedback queue , a combination of fixed-priority preemptive scheduling, round-robin, and first in, first out algorithms. In this system, threads can dynamically increase or decrease in priority depending on if it has been serviced already, or if it has been waiting extensively. Every priority level is represented by its own queue, with round-robin scheduling among

3904-410: The scheduling is combined by channel-dependent packet-by-packet dynamic channel allocation , or by assigning OFDMA multi-carriers or other frequency-domain equalization components to the users that best can utilize them. First in, first out ( FIFO ), also known as first come, first served (FCFS), is the simplest scheduling algorithm. FIFO simply queues processes in the order that they arrive in

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3968-467: The split between I/O-intensive and CPU-intensive processes is to be handled. The long-term scheduler is responsible for controlling the degree of multiprogramming. In general, most processes can be described as either I/O-bound or CPU-bound . An I/O-bound process is one that spends more of its time doing I/O than it spends doing computations. A CPU-bound process, in contrast, generates I/O requests infrequently, using more of its time doing computations. It

4032-464: The swap file), the medium-term scheduler may actually perform the role of the long-term scheduler, by treating binaries as swapped-out processes upon their execution. In this way, when a segment of the binary is required it can be swapped in on demand, or lazy loaded , also called demand paging . The short-term scheduler (also known as the CPU scheduler ) decides which of the ready, in-memory processes

4096-486: The system, and so can be said to have infinite priority. In SMP systems, processor affinity is considered to increase overall system performance, even if it may cause a process itself to run more slowly. This generally improves performance by reducing cache thrashing . IBM OS/360 was available with three different schedulers. The differences were such that the variants were often considered three different operating systems: Later virtual storage versions of MVS added

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