Scheduling (computing)

Run queue

In modern computers many processes run at once. Active processes are placed in an array called a run queue, or runqueue. The run queue may contain priority values for each process, which will be used by the scheduler to determine which process to run next. To ensure each program has a fair share of resources, each one is run for some time period (quantum) before it is paused and placed back into the run queue. When a program is stopped to let another run, the program with the highest priority in the run queue is then allowed to execute. Processes are also removed from the run queue when they ask to sleep, are waiting on a resource to become available, or have been terminated. In the Linux operating system (prior to kernel 2.6.23), each CPU in the system is given a run queue, which maintains both an active and expired array of processes. Each array contains 140 (one for each priority level) pointers to doubly linked lists, which in turn reference all processes with the given priority. The scheduler selects the next process from the active array with highest priority. When a process' quantum expires, it is placed into the expired array with some priority. When the active array contains no more processes, the scheduler swaps the active and expired arrays, hence the name O(1) scheduler. In UNIX or Linux, the sar command is used to check the run queue. The vmstat UNIX or Linux command can also be used to determine the number of processes that are queued to run or waiting to run. These appear in the 'r' column. There are two models for Run queues: one that assigns a Run Queue to each physical processor, and the other has only one Run Queue in the system (Wikipedia).

Video thumbnail

Queue Introduction

Related videos: Queue intro: https://youtu.be/KxzhEQ-zpDc Queue implementation: https://youtu.be/EoisnPvUkOA Queue code: https://youtu.be/HV-hpvuGaC4 Data Structures Source Code: https://github.com/williamfiset/algorithms My website: http://www.williamfiset.com

From playlist Queue data structure playlist

Video thumbnail

Queuing lesson 1 - Types of queues, definitions

Hi all. In this lesson on queueing we introduce you to FIFO, LIFO, Single queue single server, single queue multiple server, multiple queue single server, multiple queue multiple server, baulking, reneging, and jockeying. A lot of definitions in one video - hope it helps!

From playlist Maths A / General Course, Grade 11/12, High School, Queensland, Australia

Video thumbnail

Queue Implementation

Related videos: Queue intro: https://youtu.be/KxzhEQ-zpDc Queue implementation: https://youtu.be/EoisnPvUkOA Queue code: https://youtu.be/HV-hpvuGaC4 Data Structures Source Code: https://github.com/williamfiset/algorithms My website: http://www.williamfiset.com

From playlist Queue data structure playlist

Video thumbnail

Queue - concept and java implementation

in this tutorial, I cover the basic concepts of queue and explain java implementation of queue.

From playlist Java Coding Interview

Video thumbnail

Live Stream: Process control in C

Using fork(), exec(), and wait() in C programs. And, if there's time and interest, threading in Java.

From playlist C Programming

Video thumbnail

Queues

From playlist Week 6 2015 Shorts

Video thumbnail

Queue Code

Related videos: Queue intro: https://youtu.be/KxzhEQ-zpDc Queue implementation: https://youtu.be/EoisnPvUkOA Queue code: https://youtu.be/HV-hpvuGaC4 Data Structures Source Code: https://github.com/williamfiset/algorithms My website: http://www.williamfiset.com

From playlist Queue data structure playlist

Video thumbnail

0132 [ C++ ] Moderation queue for a multi-player game server

This is #132 in my series of live (Twitch) coding streams. This stream I put in the basic backbone for the moderation system of the game, establishing a moderation queue with events that are added whenever a new player account is created, or if a player wants to flag another player or o

From playlist Excalibur

Video thumbnail

RubyConf 2022: What does "high priority" mean? The secret to happy queues by Daniel Magliola

Like most web applications, you run important jobs in the background. And today, some of your urgent jobs are running late. Again. No matter how many changes you make to how you enqueue and run your jobs, the problem keeps happening. The good news is you're not alone. Most teams struggle w

From playlist RubyConf 2022: Mini and Houston

Video thumbnail

Writing an OS in Rust - Part 12e - A Better Executor

This is my version of Philipp Oppermann's "BlogOS". It's a baremetal operating system that can boot off of a USB stick on any BIOS-compatible machine, which is pretty amazing. I'm going to be following the whole blog, one video at a time, and running the OS using QEMU instead of booting a

From playlist Rust OS

Video thumbnail

Kernel Recipes 2015 - Solving the Linux storage scalability bottlenecks - by Jens Axboe

Flash devices introduced a sudden shift in the performance profile of direct attached storage. With IOPS rates orders of magnitude higher than rotating storage, it became clear that Linux needed a re-design of its storage stack to properly support and get the most out of these new devices.

From playlist Kernel Recipes 2015

Video thumbnail

RubyConf 2021 - Parallel testing with Ractors - Putting CPU's to work by Vinicius Stock

Parallelizing tests is an opportune way of reducing the total runtime for a test suite. Rails achieves this by forking multiple separate workers that fetch tests from a queue. In Ruby 3, Ractors introduced new mechanisms for executing code in parallel. Can they be leveraged by a test frame

From playlist RubyConf 2021

Video thumbnail

Queues & Priority Queues - Beau teaches JavaScript

Queues are a first-in first-out data structure. Also learn about priority queues. đź”— Code: http://codepen.io/beaucarnes/pen/QpaQRG?editors=0012 đź”— More info: https://www.safaribooksonline.com/library/view/learning-javascript-data/9781783554874/ch04.html Beau Carnes on Twitter: https://twit

From playlist Data Structures and Algorithms - Beau teaches JavaScript

Video thumbnail

What the heck is the event loop anyway? | Philip Roberts | JSConf EU

JavaScript programmers like to use words like, “event-loop”, “non-blocking”, “callback”, “asynchronous”, “single-threaded” and “concurrency”. We say things like “don’t block the event loop”, “make sure your code runs at 60 frames-per-second”, “well of course, it won’t work, that function

From playlist Software Development Lectures

Video thumbnail

Game Programming Patterns part 17.1 - (Reading, JS) Event Queue

We read through the Event Queue chapter of the Game Programming Patterns book and translate the code examples to JavaScript. Links code - https://github.com/brooks-builds/learning_game_design_patterns twitter - https://twitter.com/brooks_patton book - http://gameprogrammingpatterns.ocm/

From playlist Game Programming Patterns Book

Video thumbnail

Lec 25 | MIT 6.00SC Introduction to Computer Science and Programming, Spring 2011

Lecture 25: Queuing Network Models Instructor: John Guttag View the complete course: http://ocw.mit.edu/6-00SCS11 License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu

From playlist MIT 6.00SC Introduction to Computer Science and Programming

Video thumbnail

13. Dijkstra

MIT 6.006 Introduction to Algorithms, Spring 2020 Instructor: Jason Ku View the complete course: https://ocw.mit.edu/6-006S20 YouTube Playlist: https://www.youtube.com/playlist?list=PLUl4u3cNGP63EdVPNLG3ToM6LaEUuStEY This class discusses a fourth weighted single-source shortest path algor

From playlist MIT 6.006 Introduction to Algorithms, Spring 2020

Video thumbnail

RailsConf 2016 - Inside ActiveJob By Jerry D'Antonio

ActiveJob made a huge impact when it landed Rails 4.2. Most job processors support it and many developers use it. But few ever need to dig into the internals. How exactly does ActiveJob allow us to execute performant, thread-safe, asynchronous jobs in a language not known for concurrency?

From playlist RailsConf 2016

Related pages

Completely Fair Scheduler | Scheduling (computing)