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Foreground-background
Foreground-background is a scheduling algorithm that is used to control an execution of multiple processes on a single processor. It is based on two waiting lists, the first one is called foreground because this is the one in which all processes initially enter, and the second one is called background because all processes, after using all of their execution time in foreground, are moved to background. When a process becomes ready it begins its execution in foreground immediately, forcing the processor to give up execution of the current process in the background and execute the newly created process for a predefined period. This period is usually 2 or more quanta. If the process is not finished after its execution in the foreground it is moved to background waiting list where it will be executed only when the foreground list is empty. After being moved to the background, the process is then run longer than before, usually 4 quanta. The time of execution is increased because the pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheduling Algorithm
In computing, scheduling 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 process called 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 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). Goals A scheduler may aim at one or more goals, for example: * maximizing ''throughput'' (the total amount of work completed per time unit); * minimizing '' wait time'' (time from work becoming ready until the first point it begins execution); * minimizing '' latency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Run Time (program Lifecycle Phase)
In computer science, runtime, run time, or execution time is the final phase of a computer programs life cycle, in which the code is being executed on the computer's central processing unit (CPU) as machine code. In other words, "runtime" is the running phase of a program. A runtime error is detected after or during the execution (running state) of a program, whereas a compile-time error is detected by the compiler before the program is ever executed. Type checking, register allocation, code generation, and code optimization are typically done at compile time, but may be done at runtime depending on the particular language and compiler. Many other runtime errors exist and are handled differently by different programming languages, such as division by zero errors, domain errors, array subscript out of bounds errors, arithmetic underflow errors, several types of underflow and overflow errors, and many other runtime errors generally considered as software bugs which may or may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorling Kindersley
Dorling Kindersley Limited (branded as DK) is a British multinational publishing company specialising in illustrated reference books for adults and children in 63 languages. It is part of Penguin Random House, a subsidiary of German media conglomerate Bertelsmann. Established in 1974, DK publishes a range of titles in genres including travel (including DK Eyewitness travel), history, geography, science, space, nature, sports, gardening, cookery and parenting. The worldwide co-CEOs of DK is Paul Kelly and Rebecca Smart. DK has offices in New York, Melbourne, London, Munich, New Delhi, Toronto, Madrid, Beijing, and Jiangmen. DK works with licensing partners such as Disney, LEGO, DC Comics, the Royal Horticultural Society, MasterChef, and the Smithsonian Institution. DK has commissioned Mary Berry, Monty Don, Robert Winston, Huw Richards, and Steve Mould for a range of books. History DK was founded in 1974 by Christopher Dorling and Peter Kindersley in London as a book ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preemption (computing)
In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemptive scheduler usually runs in the most privileged protection ring, meaning that interruption and resuming are considered highly secure actions. Such a change in the currently executing task of a processor is known as context switching. User mode and kernel mode In any given system design, some operations performed by the system may not be preemptable. This usually applies to kernel functions and service interrupts which, if not permitted to run to completion, would tend to produce race conditions resulting in deadlock. Barring the scheduler from preempting tasks while they are processing kernel functions simplifies the kernel design at the expense of system responsiveness. The distinction between user mode and kernel mode, which det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Round-robin Scheduling
Round-robin (RR) is one of the algorithms employed by process and network schedulers in computing.Guowang Miao, Jens Zander, Ki Won Sung, and Ben Slimane, Fundamentals of Mobile Data Networks, Cambridge University Press, , 2016. As the term is generally used, time slices (also known as time quanta) are assigned to each process in equal portions and in circular order, handling all processes without priority (also known as cyclic executive). Round-robin scheduling is simple, easy to implement, and starvation-free. Round-robin scheduling can be applied to other scheduling problems, such as data packet scheduling in computer networks. It is an operating system concept. The name of the algorithm comes from the round-robin principle known from other fields, where each person takes an equal share of something in turn. Process scheduling To schedule processes fairly, a round-robin scheduler generally employs time-sharing, giving each job a time slot or ''quantum'' (its allowance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
