The document discusses various topics related to CPU scheduling in operating systems, including basic concepts, scheduling criteria, algorithms, and evaluation. It covers scheduling algorithms like first-come first-served, shortest job first, priority scheduling, round robin, and multiple queue scheduling. It also discusses concepts like context switching, dispatch latency, scheduling criteria like throughput and waiting time, and techniques for scheduling on multiple processors.
operating system
basic concept of c p u scheduling
scheduling critaria
scheduling algorithms
multi processor scheduling
real time scheduling
Thread scheduling
operating system Example
Java thread scheduling
Algorithms Evolution
Senthilkanth,MCA..
The following ppt's full topic covers Operating System for BSc CS, BCA, MSc CS, MCA students..
1.Introduction
2.OS Structures
3.Process
4.Threads
5.CPU Scheduling
6.Process Synchronization
7.Dead Locks
8.Memory Management
9.Virtual Memory
10.File system Interface
11.File system implementation
12.Mass Storage System
13.IO Systems
14.Protection
15.Security
16.Distributed System Structure
17.Distributed File System
18.Distributed Co Ordination
19.Real Time System
20.Multimedia Systems
21.Linux
22.Windows
operating system
basic concept of c p u scheduling
scheduling critaria
scheduling algorithms
multi processor scheduling
real time scheduling
Thread scheduling
operating system Example
Java thread scheduling
Algorithms Evolution
Senthilkanth,MCA..
The following ppt's full topic covers Operating System for BSc CS, BCA, MSc CS, MCA students..
1.Introduction
2.OS Structures
3.Process
4.Threads
5.CPU Scheduling
6.Process Synchronization
7.Dead Locks
8.Memory Management
9.Virtual Memory
10.File system Interface
11.File system implementation
12.Mass Storage System
13.IO Systems
14.Protection
15.Security
16.Distributed System Structure
17.Distributed File System
18.Distributed Co Ordination
19.Real Time System
20.Multimedia Systems
21.Linux
22.Windows
cpu scheduling bassically tell us about the outer structure or the managemnet of the computer tha how it is done ,it bassically tell us about how our cpu is scheduled.
This Presention contains Cpu scheduling algorithms,Scheduling Criteria,process sychroization,mutilevel feed back que,critical section problem anad semaphores,Synchoroniztion hardware
cpu scheduling bassically tell us about the outer structure or the managemnet of the computer tha how it is done ,it bassically tell us about how our cpu is scheduled.
This Presention contains Cpu scheduling algorithms,Scheduling Criteria,process sychroization,mutilevel feed back que,critical section problem anad semaphores,Synchoroniztion hardware
CPU Scheduling is the process through which we can find the best way to check the shortest and fastest working. Different Algorithms are explained here in this chapter. First-come-first-servers, Shortest Job First, Shortest remaining time first,
Round Robin, Priority Scheduler.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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O P E R A T I N G S Y S T E M S
Module 5 : CPU Scheduling
• Basic Concepts
• Scheduling Criteria
• Scheduling Algorithms
• Multiple-Processor Scheduling
• Real-Time Scheduling
• Algorithm Evaluation
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Module 5: CPU Scheduling
• Basic Concepts
• Scheduling Criteria
• Scheduling Algorithms
• Multiple-Processor Scheduling
• Real-Time Scheduling
• Algorithm Evaluation
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Basic Concepts
• Maximum CPU utilization obtained with
multiprogramming
• CPU–I/O Burst Cycle – Process execution consists of
a cycle of CPU execution and I/O wait.
• CPU burst distribution
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Alternating Sequence of CPU And I/O Bursts
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Histogram of CPU-burst Times
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CPU Scheduler
• Selects from among the processes in memory that are
ready to execute, and allocates the CPU to one of them.
• CPU scheduling decisions may take place when a
process:
1.Switches from running to waiting state.
2.Switches from running to ready state.
3.Switches from waiting to ready.
4.Terminates.
• Scheduling under 1 and 4 is nonpreemptive.
• All other scheduling is preemptive.
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Dispatcher
• Dispatcher module gives control of the CPU to the
process selected by the short-term scheduler; this
involves:
– switching context
– switching to user mode
– jumping to the proper location in the user program
to restart that program
• Dispatch latency – time it takes for the dispatcher to
stop one process and start another running.
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Scheduling Criteria
• CPU utilization – keep the CPU as busy as possible
• Throughput – # of processes that complete their execution
per time unit
• Turnaround time – amount of time to execute a particular
process
• Waiting time – amount of time a process has been waiting
in the ready queue
• Response time – amount of time it takes from when a
request was submitted until the first response is produced,
not output (for time-sharing environment)
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Optimization Criteria
• Max CPU utilization
• Max throughput
• Min turnaround time
• Min waiting time
• Min response time
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First-Come, First-Served (FCFS) Scheduling
• Example: Process Burst Time
P1 24
P2 3
P3 3
• Suppose that the processes arrive in the order: P1 , P2 , P3
The Gantt Chart for the schedule is:
• Waiting time for P1 = 0; P2 = 24; P3 = 27
• Average waiting time: (0 + 24 + 27)/3 = 17
P1 P2 P3
24 27 300
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FCFS Scheduling (Cont.)
Suppose that the processes arrive in the order
P2 , P3 , P1 .
• The Gantt chart for the schedule is:
• Waiting time for P1 = 6; P2 = 0; P3 = 3
• Average waiting time: (6 + 0 + 3)/3 = 3
• Much better than previous case.
• Convoy effect short process behind long process
P1P3P2
63 300
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Shortest-Job-First (SJR) Scheduling
• Associate with each process the length of its next CPU
burst. Use these lengths to schedule the process with
the shortest time.
• Two schemes:
– nonpreemptive – once CPU given to the process it
cannot be preempted until completes its CPU burst.
– Preemptive – if a new process arrives with CPU burst
length less than remaining time of current executing
process, preempt. This scheme is know as the
Shortest-Remaining-Time-First (SRTF).
• SJF is optimal – gives minimum average waiting time for
a given set of processes.
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ProcessArrival Time Burst Time
P1 0.0 7
P2 2.0 4
P3 4.0 1
P4 5.0 4
• SJF (non-preemptive)
• Average waiting time = (0 + 6 + 3 + 7)/4 - 4
Example of Non-Preemptive SJF
P1 P3 P2
73 160
P4
8 12
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Example of Preemptive SJF
ProcessArrival Time Burst Time
P1 0.0 7
P2 2.0 4
P3 4.0 1
P4 5.0 4
• SJF (preemptive)
• Average waiting time = (9 + 1 + 0 +2)/4 - 3
P1 P3P2
42 110
P4
5 7
P2 P1
16
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Determining Length of Next CPU Burst
• Can only estimate the length.
• Can be done by using the length of previous CPU bursts, using
exponential averaging.
1. tn=actual lenght of nth
CPU burst
2. τn+1= predicted value for the next CPU burst
3 . α , 0≤α≤1
4. Define:
τn=1=α tn+(1−α)τ n .
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Examples of Exponential Averaging
=0
n+1 = n
– Recent history does not count.
=1
– n+1 = tn
– Only the actual last CPU burst counts.
• If we expand the formula, we get:
n+1 = tn+(1 - ) tn -1 + …
+(1 - )j tn -1 + …
+(1 - )n=1 tn 0
• Since both and (1 - ) are less than or equal to 1, each
successive term has less weight than its predecessor.
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Priority Scheduling
• A priority number (integer) is associated with each process
• The CPU is allocated to the process with the highest priority
(smallest integer highest priority).
– Preemptive
– nonpreemptive
• SJF is a priority scheduling where priority is the predicted next CPU
burst time.
• Problem Starvation – low priority processes may never execute.
• Solution Aging – as time progresses increase the priority of the
process.
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Round Robin (RR)
• Each process gets a small unit of CPU time (time quantum),
usually 10-100 milliseconds. After this time has elapsed, the
process is preempted and added to the end of the ready queue.
• If there are n processes in the ready queue and the time
quantum is q, then each process gets 1/n of the CPU time in
chunks of at most q time units at once. No process waits more
than (n-1)q time units.
• Performance
– q large FIFO
– q small q must be large with respect to context switch,
otherwise overhead is too high.
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Example: RR with Time Quantum = 20
Process Burst Time
P1 53
P2 17
P3 68
P4 24
• The Gantt chart is:
• Typically, higher average turnaround than SJF, but better response.
P1 P2 P3 P4 P1 P3 P4 P1 P3 P3
0 20 37 57 77 97 117 121 134 154 162
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How a Smaller Time Quantum Increases Context Switches
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Turnaround Time Varies With The Time Quantum
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Multilevel Queue
• Ready queue is partitioned into separate queues:
foreground (interactive)
background (batch)
• Each queue has its own scheduling algorithm,
foreground – RR
background – FCFS
• Scheduling must be done between the queues.
– Fixed priority scheduling; i.e., serve all from foreground
then from background. Possibility of starvation.
– Time slice – each queue gets a certain amount of CPU
time which it can schedule amongst its processes; i.e.,
80% to foreground in RR
– 20% to background in FCFS
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Multilevel Queue Scheduling
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Multilevel Feedback Queue
• A process can move between the various queues; aging
can be implemented this way.
• Multilevel-feedback-queue scheduler defined by the
following parameters:
– number of queues
– scheduling algorithms for each queue
– method used to determine when to upgrade a process
– method used to determine when to demote a process
– method used to determine which queue a process will
enter when that process needs service
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Multilevel Feedback Queues
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Example of Multilevel Feedback Queue
• Three queues:
– Q0 – time quantum 8 milliseconds
– Q1 – time quantum 16 milliseconds
– Q2 – FCFS
• Scheduling
– A new job enters queue Q0 which is served FCFS. When
it gains CPU, job receives 8 milliseconds. If it does not
finish in 8 milliseconds, job is moved to queue Q1.
– At Q1 job is again served FCFS and receives 16
additional milliseconds. If it still does not complete, it is
preempted and moved to queue Q2.
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Multiple-Processor Scheduling
• CPU scheduling more complex when multiple CPUs are
available.
• Homogeneous processors within a multiprocessor.
• Load sharing
• Asymmetric multiprocessing – only one processor
accesses the system data structures, alleviating the need
for data sharing.
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Real-Time Scheduling
• Hard real-time systems – required to complete a critical
task within a guaranteed amount of time.
• Soft real-time computing – requires that critical processes
receive priority over less fortunate ones.
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Dispatch Latency
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Algorithm Evaluation
• Deterministic modeling – takes a particular predetermined
workload and defines the performance of each algorithm for that
workload.
• Queuing models
• Implementation
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Evaluation of CPU Schedulers by Simulation