This document summarizes operating system process scheduling. It discusses short, long, and medium term schedulers and the CPU-IO burst cycle. It describes preemptive scheduling and different scheduling algorithms like first-come first-served, shortest job first, priority, and round robin. It also discusses scheduling criteria for optimization and different performance evaluation methods. Finally, it provides an overview of process scheduling in Linux and Windows NT systems.
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.
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.
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.
This Presention contains Cpu scheduling algorithms,Scheduling Criteria,process sychroization,mutilevel feed back que,critical section problem anad semaphores,Synchoroniztion hardware
Task scheduling is needed to maintain every process that comes with a processor in parallel processing. In several conditions, not every algorithm works better on the significant problem. Sometimes FCFS algorithm is better than the other in short burst time while Round Robin is better for multiple processes in every single time. But we cannot predict what process will come after. Average Waiting Time is a standard measure for giving credit to the scheduling algorithm. Several techniques have been applied to maintain the process in order to make the CPU performance in normal. The objective of this paper is to compare three algorithms, FCFS, SJF and Round Robin. Finally, we know which algorithm is more suitable for the certain process.
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.
This Presention contains Cpu scheduling algorithms,Scheduling Criteria,process sychroization,mutilevel feed back que,critical section problem anad semaphores,Synchoroniztion hardware
Task scheduling is needed to maintain every process that comes with a processor in parallel processing. In several conditions, not every algorithm works better on the significant problem. Sometimes FCFS algorithm is better than the other in short burst time while Round Robin is better for multiple processes in every single time. But we cannot predict what process will come after. Average Waiting Time is a standard measure for giving credit to the scheduling algorithm. Several techniques have been applied to maintain the process in order to make the CPU performance in normal. The objective of this paper is to compare three algorithms, FCFS, SJF and Round Robin. Finally, we know which algorithm is more suitable for the certain process.
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 followed by I/O burst
CPU burst distribution is of main concern
Operating Systems Process Scheduling Algorithmssathish sak
CPU scheduling big area of research in early ‘70s
Many implicit assumptions for CPU scheduling:
One program per user
One thread per program
Programs are independent
These are unrealistic but simplify the problem
Does “fair” mean fairness among users or programs?
If I run one compilation job and you run five, do you get five times as much CPU?
Often times, yes!
Goal: dole out CPU time to optimize some desired parameters of the system.
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
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Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
1. 1
Operating System
Process Scheduling
(Ch 4.2, 5.1 - 5.3)
Schedulers
F Short-Term
– “Which process gets the CPU?”
– Fast, since once per 100 ms
F Long-Term (batch)
– “Which process gets the Ready Queue?”
F Medium-Term (Unix)
– “Which Ready Queue process to memory?”
– Swapping
CPU-IO Burst Cycle
add
read
(I/O Wait)
store
increment
write
(I/O Wait)
Burst Duration
Frequency
Preemptive Scheduling
F Four times to re-schedule
1 Running to Waiting (I/O wait)
2 Running to Ready (time slice)
3 Waiting to Ready (I/O completion)
4 Termination
F #2 optional ==> “Preemptive”
F Timing may cause unexpected results
– updating shared variable
– kernel saving state
Question
F What Performance Criteria Should the
Scheduler Seek to Optimize?
– Ex: CPU minimize time spent in queue
– Others?
Scheduling Criteria
1 CPU utilization (40 to 90)
2 Throughput (processes / hour)
3 Turn-around time
4 Waiting time (in queue)
F Maximize #1, #2 Minimize #3, #4
F Response time
– Self-regulated by users (go home)
– Bounded ==> Variance!
2. 2
First-Come, First-Served
Process
A
B
C
Burst Time
8
1
1
0 8 9 10
A B C
F Avg Wait Time (0 + 8 + 9) / 3 = 5.7
Gantt
Chart
Shortest Job First
0 1 2 10
A
B C
F Avg Wait Time (0 + 1 + 2) / 3 = 1
F OptimalAvg Wait
F Prediction tough … Ideas?
Process
A
B
C
Burst Time
8
1
1
Priority Scheduling
F SJF is a special case
Process
A
B
C
Burst Time
8
1
1
Priority
2
1
3
0 1 9 10
A
B C
F Avg Wait Time (0 + 1 + 9) / 3 = 3.3
Priority Scheduling Criteria?
F Internal
– open files
– memory requirements
– CPU time used - time slice expired (RR)
– process age - I/O wait completed
F External
– $
– department sponsoring work
– process importance
– super-user (root) - nice
Round Robin
F Fixed time-slice and Preemption
Process
A
B
C
Burst Time
5
3
3
B C
A B C A B C
A A
F Avg = (8 + 9 + 11) / 3 = 9.3
F FCFS? SJF?
8 9 11
Round Robin Fun
Process
A
B
C
Burst Time
10
10
10
F Turn-around time?
– q = 10
– q = 1
– q --> 0
3. 3
More Round Robin Fun
Process
A
B
C
D
Burst Time
6
3
1
7
1 2 3 4 5 6 7
Time Quantum
Avg.
Turn-around
Time
Rule:
80% within
one quantum
Fun with Scheduling
Process
A
B
C
Burst Time
10
1
2
Priority
2
1
3
F Gantt Charts:
– FCFS
– SJF
– Priority
– RR (q=1)
F Performance:
– Throughput
– Waiting time
– Turnaround time
More Fun with Scheduling
Process
A
B
C
Arrival Time
0.0
0.4
1.0
Burst Time
8
4
1
F Turn around time:
– FCFS
– SJF
– q=1 CPU idle
– q=0.5 CPU idle
Multi-Level Queues
System
Priority 1
Priority 2
Priority 3
Interactive
Batch
F Categories of processes
F Run all in 1 first, then 2 …
F Starvation!
F Divide between queues: 70% 1, 15% 2 …
... ...
Multi-Level Feedback Queues
Queue
Priority 1
Priority 2
Priority 3
Queue
Queue
1 Quantum
2 Quanta
4 Quanta
F Time slice expensive but want interactive
F Consider process needing 100 quanta
– 1, 4, 8, 16, 32, 64 = 7 swaps!
F Favor interactive users
... ... ...
Evaluating Scheduling Algorithms
F With all these possible scheduling
algorithms, how to choose one?
– Ease of implementation
– Efficiency of implementation / low overhead
– Performance evaluation (next slide)
4. 4
Performance Evaluation Methods
F Deterministic methods / Gantt charts
– Use more realistic workloads
F Queueing theory
– Mathematical techniques
– Uses probablistic models of jobs / CPU
utilization
F Simulation
– Probabilistic or trace-driven
Linux Process Scheduling
F Two classes of processes:
– Real-Time
– Normal
F Real-Time:
– Always run Real-Time above Normal
– Round-Robin or FIFO
– “Soft” not “Hard”
Linux Process Scheduling
F Normal: Credit-Based
– process with most credits is selected
– time-slice then lose a credit (0, then suspend)
– no runnable process (all suspended), add to
every process:
credits = credits/2 + priority
F Automatically favors I/O bound processes
Questions
F What is a PCB?
F List steps that occur during interrupt
F Explain how SJF works
F True or False:
– FCFS is optimal in terms of avg waiting time
– Most processes are CPU bound
– The shorter the time quantum, the better
F micro-shell.c?
Interrupt Handling
F Stores program counter (hardware)
F Loads new program counter (hardware)
– jump to interrupt service procedure
F Save PCB information (assembly)
F Set up new stack (assembly)
F Set “waiting” process to “ready” (C)
F Re-schedule (probably awakened process) (C)
– “dispatcher” in SOS, “schedule” in Linux
F If new process, called a context-switch
Outline
F Processes 4
– PCB 4
– Interrupt Handlers 4
F Scheduling
– Algorithms 4
– Linux
– WinNT ←
5. 5
Windows NT Scheduling
F Basic scheduling unit is a thread
F Priority based scheduling per thread
F Preemptive operating system
F No shortest job first, no quotas
Priority Assignment
F NT kernel uses 31 priority levels
– 31 is the highest; 0 is system idle thread
– Realtimepriorities: 16 - 31
– Dynamic priorities: 1 - 15
F Users specify a priority class:
u realtime (24) , high (13), normal (8) and idle (4)
– and a relative priority:
u highest (+2), above normal (+1), normal (0), below
normal (-1), and lowest (-2)
– to establish the starting priority
F Threads also have a current priority
Quantum
F Determines how long a Thread runs once
selected
F Varies based on:
– NT Workstation or NT Server
– Intel or Alpha hardware
– Foreground/Background application threads
F How do you think it varies with each?
Dispatcher Ready List
F Keeps track of all
Ready-to-execute
threads
F Queue of threads
assigned to each level
Dispatcher
Ready List
11
10
9
8
7
Ready Threads
FindReadyThread
F Locates the highest priority thread that is
ready to execute
F Scans dispatcher ready list
F Picks front thread in highest priority
nonempty queue
F When is this like round robin?
Boosting and Decay
F Boost priority
– Event that “wakes” blocked thread
– Boosts never exceed priority 15 for dynamic
– Realtime priorities are not boosted
F Decay priority
– by one for each quantum
– decays only to starting priority (no lower)
6. 6
Starvation Prevention
F Low priority threads may never execute
F “Anti-CPU starvation policy”
– thread that has not executed for 3 seconds
– boost priority to 15
– double quantum
F Decay is swift not gradual after this boost