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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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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1answer
251 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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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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1answer
28 views

Repeatedly finding and deleting maximal independent sets on a graph: Number of necessary iterations in restricted cases

I am trying to design a parallel scheduling algorithm based on a constraint graph $G=(V,E)$ in which each node represents a task and each edge $e=(v_1, v_2)$ signifies, that tasks $v_1$ and $v_2$ can ...
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1answer
746 views

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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2answers
490 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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1answer
86 views

A task-scheduling problem as a matroid (CLRS book)

I don't understand very well section 16.5 of the 3rd edition of the famous Introduction to Algorithms book, known as CLRS. It defines the problem of scheduling unit-...
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1answer
485 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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1answer
60 views

CPU scheduling Decisions

Operating System - CPU scheduling Decisions The question above talks about why CPU scheduling does not take place when ready to running. But I wonder why CPU scheduling does not take place when new ...
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1answer
39 views

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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2-Dimensional interval scheduling problem

I have a problem that is similar to the conventional interval scheduling algorithm but it is two dimensional, so I have another metric to take into account. My dataset format: Cars with the start and ...
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1answer
86 views

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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Job Shop Problem: How do you get an ordered sequence of operations from the disjunctive acyclic graph?

Intro The job shop problem is a classic scheduling theory problem. Given $N$ jobs and $M$ machines, a typical goal of the JSP is to minimise the makespan (starting time of the last operation + its ...
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Scheduling Repeating, Flexible Intervals with Restrictions on Overlap

I work in 52:17 work:break intervals, as there's some evidence showing it's an effective way to structure the day. However, meetings or planned breaks often require shifting that schedule, moving, ...
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1answer
67 views

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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Scheduling algorithm for a student's study times given assignments, expected time, due dates, and class times

I would like to create an algorithm that advises a student when they should work on certain assignments given the expected time each assignment will take, and the due date of each assignment. Say that ...
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28 views

Cyclic finite scheduling algorithm

I have a scheduling problem with the following specifications: A single machine is used. $n$ jobs $\mathbb{J} = \{J_1,...,J_n\}$ are available from the start $t = 0$. Each job can be executed several ...
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1answer
6k views

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
103 views

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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Does having a similar constraint while reducing a problem to similar problem to prove np hard means they are same?

I have been trying to find the computational complexity of my optimization problem and found that it is Np-Hard. To prove it to Np-Hard, I try reducing it Nurse Scheduling Problem. I am quite confused ...
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1answer
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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
76 views

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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23 views

Test data for tasks that communicate over network

I am working on a load balancer that schedules tasks that communicate over network. I want to test its performance, but I'm struggling to find test data for it. Currently I try to extract relevant ...
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6answers
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What is the average turnaround time?

For the following jobs: The average wait time would be using a FCFS algorithm: (6-6)+(7-2)+(11-5)+(17-5)+(14-1) -> 0+5+6+10+13 -> 34/5 = 7 (6.8) What would the average turnaround time be?
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1answer
485 views

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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How to place the deadlines in “Earliest deadline first scheduling” in this question?

So I followed this tutorial to get the concept of "Earliest deadline first scheduling". I have to implement this task >>> TASK. Now the thing which I am not getting in this Task is ...
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What is a good approach to deciding which jobs (from a list of HPC jobs) should be ran locally vs. on the cloud given time & cost constraints?

Cloud computing has transformed the landscape of compute operations. Of course, there are still many labs/businesses with local, large-scale compute clusters. For those businesses who keep the ...
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1answer
68 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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97 views

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
694 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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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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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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1answer
90 views

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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12 views

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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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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66 views

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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23 views

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
152 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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34 views

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
488 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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44 views

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
32 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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