Questions tagged [scheduling]

Questions about the optimisation problem of ordering a set of tasks so that some objective function (e.g. makespan) is minimised. The set of constraints is crucial; in particular, there is a large body of research covering online variants. Use the process-scheduling tag for questions specifically about scheduling in operating systems.

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1answer
56 views

Greedy algorithm for job scheduling

Consider the following greedy algorithm for Job Scheduling. For each new task, assign the task to processor with the shortest uptime. How to prove that this algorithm has an approximation ratio of ...
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Algorithm for scheduling unit time tasks with arrival times and deadlines

Suppose we have $n$ tasks to order over $n$ days. Each tasks takes 1 day to be completed. Each task has a start date when the task becomes available and a deadline when the task must be delivered. ...
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135 views

Calculating minimum processing time for many recipes and tools

I originally asked this question on StackOverflow but a comment was made to the effect that my problem pertains to Job Shop Scheduling and that it was more of a comp sci problem than a programming ...
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1answer
140 views

Questions regarding CPU scheduling algorithms ( Round Robin and Priority scheduling )

Consider the following processes : 1) My First Question is if we need to schedule them using preemptive priority scheduling with Round-Robin for equal processes priorities with a quantum of 3. Here ...
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Dynamic job scheduling with earliest time and deadline

I have a real life algorithmic problem and I'm trying to find out if there is any similar widely known algorithmic problem with known solutions that I could adapt to my particular use case. I want to ...
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1answer
498 views

DP for Weighted Interval Scheduling: why is sorting by finish time necessary?

Problem : In the weighted interval scheduling problem, we want to find the maximum-weight subset of nonoverlapping jobs, given a set $J$ of jobs that have weights associated with them. Job $i \in J$ ...
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Algorithm favours CPU bound or I/O bound processes

Some scheduling algorithms favour CPU bound processes while others favour I/O bound processes. Which algorithm favours which type of process? My answers: SJF favours I/O bound processes.Explanation: ...
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What is the significance of Bellman-Ford and linear programming for scheduling and makespans?

CLRS exercise 24.4-9 says the following: Show that the Bellman-Ford algorithm, when run on the constraint graph for a system $Ax \leq b$ of difference constraints, minimizes the quantity $\max_i\{x_i\...
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1answer
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Task calendar scheduling algorithm

I want to write a scheduling algorithm for the following scenario: There is a set of tasks to complete, each one with a due date, difficulty (easy, normal, hard) and progress on the task. The idea is ...
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Extending the token bucket algorithm

I've been looking at implementing a local rate limiting solution satisfying certain guarantees. I've found surprisingly little literature on the extensions of the token bucket algorithm to hierarchies....
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436 views

Scheduling / Queuing jobs with multiple different workers

I have a stream of jobs (so I don't know upfront how many jobs). And I have N workers in the system. Now I want to schedule / queue a job to one worker (a worker can have multiple jobs in his queue). ...
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440 views

Find optimal quantum at Round Robin Scheduling algorithm

In this process list situation How can I find the quantum time ( time slice ) at 80% of CPU time ? I found only for 100% of CPU time, so I don't know if it's the same for 80% case B.T.Q= [mean + ...
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Optimal Selection of Non-Overlapping Jobs

I'm trying to find what the family of problem is - as well as an approach - for the following: I have a set of tasks T = [t1, ..., tn] to do, each of which has a corresponding reward ri. Each task ...
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Schedule X Classes In N Classrooms

I would really appreciate any thought on this, or under which category does this problem fall (Interval scheduling, Interval partitioning,...) I am really out of thoughts I have X number of classes ...
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1answer
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Designing a rationing algorithm for a store

Suppose I have a store and I have n units of item x. I want to sell all n units at the end of the day. I do not know how many customers will be coming in today. One customer could theoretically come ...
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1answer
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Early Deadline First (EDF) scheduling in real-time systems feasibility test proof

I am trying to prove Theorem 6.2 on page 127 of the book Real-Time Systems by Jane W. S. Liu: http://www.cse.hcmut.edu.vn/~thai/books/2000%20_%20Liu-%20Real%20Time%20Systems.pdf It is based on Early ...
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Operating System that had the convoy effect

I read some things about the convoy effect (or problem), and at one source there was mentioned, that it was "implemented" in "historic" or very old outdated operating systems. I ...
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Algorithm for assigning 2 list of different objects into connected slots optimally

I would to optimally assign objects into slots. There are 2 lists of 2 different elements that have to be assigned. An element from list 1 must be grouped with an element from list 2 into one slot. ...
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Why the proof of the hyperbolic bound for rate-monotonic scheduling works?

Recently I'm trying to prove the hyperbolic bound for rate-monotonic scheduling (RMS). [original paper] http://retis.sssup.it/~giorgio/paps/2001/ecrts01-hb.pdf [more formal paper] https://ieeexplore....
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How to calculate average waiting time for round robin cpu scheduling?

I have tried to calculate average waiting time for the below details there are two answers I'm getting using two methods I'm not understanding which one is correct? The time quantum is 2 This is the ...
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1answer
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Default scan order in SCAN and LOOK disk scheduling algorithms

I've been learning various disk scheduling algorithms in Operating systems. I wanted to know if there was any default scan order in SCAN, C-SCAN, LOOK and C-LOOK algorithms, like towards higher ...
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1answer
35 views

Interval Scheduling problem with more than 1 machine

There are 2 machines. Each task either requires 1 or 2 machines to run (ie, a 1-machine task can run in parallel with another 1-machine task but a 2-machine task occupies both machine The list of n ...
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1answer
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Tournament Scheduling Problem

I am trying to design an algorithm to compute the solution to this problem. Given a list of n tournaments with a name, start_date, end_date, latitude and longitude, find the list of p tournaments in ...
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Maximize the minimum gap while scheduling within intervals?

Problem There are N intervals in which a particular integer can be chosen. What is the maximum possible minimum gap between each integer if one integer is chosen for each of those intervals? For ...
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Gantt chart for Round Robin Scheduling using only arrival and completion time

I had the following question in my Operating System 'CPU- Scheduling' assignment- 4 processes A,B,C,D have estimated time of completion of 5,7,9,11 ns each. They are scheduled in a round-robin fashion ...
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About a fair scheduler

Is there any difference between having a fair scheduler (an adversary cannot reorder messages sent by correct processes) and having a reliable point-to-point FIFO link among processes?
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How to justify the choice of using a specific metaheuristic?

For a problem how to justify the use of a metaheuristic upon another? For exemple for scheduling problem, could the same heuristic be efficient for different variants of the problem? What are the ...
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Operating system scheduling doubt

Consider a uniprocessor system executing three tasks T1,T2 and T3 each of which is composed of an infinite sequence of jobs (or instances) which arrive periodically at intervals of 3, 7 and 20 ...
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1answer
141 views

What's the name of this DFS variation

Classical DFS: A set of tasks with precedence constraints (saying “u must be done before v”) are given. This problem can be represented by a directed graph. We assume that the graph is acyclic. A DFS ...
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How does the Fetch-Decode-Execute-Reset (FDER) cycle work?

How is this different to the Fetch-decode-execute (FDE) cycle? I have an understanding of the FDE cycle and how the CPU works, although I came across a FDER cycle, when reading about the CPU ...
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What are the differences between Earliest Deadline First (EDF) and Earliest Due Date (EDD)?

From my understanding, the EDF (Earliest Deadline First) rule is essentially an iterative "version" of the EDD (Earliest Due Date) rule, which allows for preemption. At every point in time, ...
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I'ld like a better algorithm for scheduling tutors to fill a set of shifts

My problem is as follows: I have a set of shifts at various locations that need to be filled by tutors. A simple example would be basic math in room A on M, W, F from 9-11am and Sa from 12-3 pm. ...
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Scheduling jobs online on 3 identical machines - a lower bound of 5/3

Consider the Online Scheduling Problem with $3$ identical machines. Jobs, with arbitrary size arrive online one after another and need to be scheduled immediately on one of the $3$ machines without ...
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1answer
399 views

Greedy sequential/parallel task scheduling

We have N tasks that need to be scheduled for processing. Each task consists of two parts that need to executed in order. The first one is guarded by a mutex and ...
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Understanding proofs Lemma 11 & 10 in this specific Computer Science Scheduling Paper

I'm having a hard time wrapping my head around the proofs Lemma 11 and Lemma 10 (Pages 10 and 11) in this paper called: Preemptive and Non-Preemptive Real-Time UniProcessor Scheduling. Generally the ...
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Scheduling algorithm for overlapping jobs - single resource?

I have a single resource that will need to shared for running multiple parallel jobs. Think of the resource as a straight line numbered from 1 to 100. The jobs occupy part of the line while they are ...
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1answer
30 views

Scheduling problem

I am trying to find in the literature how to solve the following problem: Suppose we have a list of $n$ jobs. Some of the jobs should be scheduled after other jobs (i.e., job a should be done after ...
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2answers
4k views

SCAN and CSCAN algorithms of disk scheduling

I am having hard time understanding the working of SCAN and CSCAN algorithm of disk scheduling.I understood FCFS,Closest Cylinder Next but heard that SCAN resembles elevator mechanism and got confused....
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1answer
57 views

How to represent sums of piecewise quadratic functions for efficient optimisation?

I'm trying to implement a decision procedure for finding solutions to a scheduling problem; this involves computing the point in time which is under the most contention. Each task to be scheduled has ...
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Disk scheduling algorithm - SCAN and C-SCAN

I'm studying several disk scheduling algorithms; however, I'm kinda confused with SCAN. I understand the concept, but I don't understand the example given in the book. I think that the author made a ...
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2answers
52 views

Weighted interval set scheduling problem

Given a set of weighted intervals, the weighted interval scheduling problem is to select a subset of the intervals such that none of the intervals in the subset overlap and the sum of their weights is ...
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29 views

How to compute this CPU scheduling exercise?

How can I compute this type of problem? My doubts are one the number of jobs, I have tried drawing a Gantt chart, but it becomes huge and unmanageable. How am I supposed to represent the results? ...
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1answer
68 views

interval scheduling variant: 1 machine with 2 tasks need to complete only

I am looking for an optimal solution of an interval scheduling variant. Basically, given n tasks with the start time Si and end time Ei, select EXACTLY two tasks whose execution periods are maximum ...
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Scheduling is NP-Hard via vertex cover

Are there any existing proofs involving a reduction of the single machine scheduling problem (in any of its forms really) from vertex cover in order to prove its NP-hardness? Particularly looking for ...
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1answer
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How can the 4-bit page number and 8-bit offset as well as the page table be used to a answer a question like, “how big is each page”? etc

No more information required. I would just like to know how to use the information provided.
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Does anyone know the answer the following questions on converting logical - physical addresses

Due to the unforeseen pandemic, I am unable to speak to my tutor about the following question. I have emailed him, but I have not had an answer for weeks. Can someone please enlighten me. Image and ...
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2answers
103 views

Proof of greedy algorithm to minimize cost of job assignment over unlimited number of machines

I'm trying to prove a greedy algorithm works for a specific problem: You have $n$ jobs and some finite number of machines. (The number of machines doesn't matter; we assume you have enough to run ...
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2D interval scheduling problem

Suppose I give you $n$ axis-aligned rectangles with a specified width, height, and x-position (of the left edge) $\{(w_i, h_i, x_i) \mid i \in \{0, \ldots, n - 1\}\}$, as well as a bound $(y_\mathrm{...
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“Job” scheduling with skill restrictions

I was given this real life problem and was asked if there would be a way to optimize this, I realize that this is akin to a job scheduling problem, but I can't seem to grasp how to make it work with ...
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How should I make this algorithm / What algorithms are avaiable for scheduling tasks

As part of a school assessment task, I am required to create a solution which incorporates a complex algorithm. I have an idea for the algorithm and it goes as followed; A complex algorithm which ...

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