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| {{Unreferenced|date=December 2009}}
| | Hello. Let me introduce the writer. Her name is Refugia Shryock. One of the extremely best issues in the globe for me is to do aerobics and I've been performing it for quite a while. Since she was eighteen she's been operating as a meter reader but she's usually wanted her own company. California is our beginning location.<br><br>Feel free to visit my web-site: [http://www.gigatronika.com/social/profile/LSmart home std test kit] |
| '''Least Slack Time''' (LST) scheduling is a [[scheduling algorithm]]. It assigns priority based on the ''slack time'' of a process. Slack time is the amount of time left after a job if the job was started now. This algorithm is also known as '''Least Laxity First'''. Its most common use is in embedded systems, especially those with multiple processors. It imposes the simple constraint that each process on each available processor possesses the same run time, and that individual processes do not have an affinity to a certain processor. This is what lends it a suitability to embedded systems.
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| ==Slack time==
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| This scheduling algorithm first selects those processes that have the smallest "slack time". Slack time is defined as the temporal difference between the deadline, the ready time and the run time.
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| More formally, the ''slack time'' for a process is defined as:
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| <math>(d - t) - c'</math>
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| where <math>d</math> is the process deadline, <math>t</math> is the real time since the cycle start, and <math>c'</math> is the remaining computation time.
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| ==Applications==
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| In Realtime Scheduling Algorithms for periodic jobs, an acceptance test is needed before accepting the sporadic jobs with its hard deadline. One of the simpliest acceptance test for the sporadic job is, calculating the sum amount of slack time between the realeasetime and deadline of the job.
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| ==Suitability==
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| LST scheduling is most useful in systems comprising mainly aperiodic tasks, because no prior assumptions are made on the events' rate of occurrence. The main weakness of LST is that it does not look ahead, and works only on the current system state. Thus, during a brief overload of system resources, LST can be sub-optimal. It will also be suboptimal when used with uninterruptible processes. However, like [[Earliest deadline first scheduling|earliest deadline first]], and unlike [[Rate-monotonic scheduling|rate monotonic scheduling]], this algorithm can be used for processor utilization up to 100%.
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| {{DEFAULTSORT:Least Slack Time Scheduling}}
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| [[Category:Scheduling algorithms]]
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Latest revision as of 04:41, 29 August 2014
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