Virtual Memory Scheduling Prof Aiman Hanna Department of

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Virtual Memory & Scheduling © Prof. Aiman Hanna Department of Computer Science Concordia University

Virtual Memory & Scheduling © Prof. Aiman Hanna Department of Computer Science Concordia University Montreal, Canada

Issues Related to Virtual Memory l What happen if the Page table is too

Issues Related to Virtual Memory l What happen if the Page table is too big to entirely be stored in the main memory? l What if the page table is too small? l What if it falls in between? l Can the cache memory be used to enhance performance? 2

Scheduling l Different components of the scheduler: Enqueuer, Dispatcher, Context switcher, … l Functionality

Scheduling l Different components of the scheduler: Enqueuer, Dispatcher, Context switcher, … l Functionality of each of these components l Context switching operations 3

Scheduling l Voluntary vs Involuntary CP sharing l Problems with the voluntary scheme l

Scheduling l Voluntary vs Involuntary CP sharing l Problems with the voluntary scheme l What is a time quantum 4

Scheduling l Preemptive vs Non-preemptive strategies l Potential problems with the Non-preemptive strategies l

Scheduling l Preemptive vs Non-preemptive strategies l Potential problems with the Non-preemptive strategies l Definitions of: Service Time, Response Time, Wait Time & Turnaround Time 5

Non-preemptive Strategies l FIFO l SJN l Priority l Deadline 6

Non-preemptive Strategies l FIFO l SJN l Priority l Deadline 6

Non-preemptive Strategies l How system performance can be enhanced just by selecting a specific

Non-preemptive Strategies l How system performance can be enhanced just by selecting a specific scheduling scheme? l Is there any cost/overhead/problems of using any of these strategies l Advantages & Disadvantages of these nonpreemptive strategies l Can any of these strategies be implemented as preemptive? 7

Where is this week coverage in the textbook? l As mentioned, the coverage related

Where is this week coverage in the textbook? l As mentioned, the coverage related to Issues Related to Virtual Memory are mainly based on class coverage and hand-notes taken in class. See next slide for coverage related to Scheduling 8

Where is this week coverage in the textbook? l Chapter 7: Section 7. 1

Where is this week coverage in the textbook? l Chapter 7: Section 7. 1 to 7. 5 with the following exceptions: Definitions of Service time, wait time, and turnaround time (page 262) MUST be taken from the notes supplied in class (if you missed this class, please ask me for these notes) l Examples of the different scheduling schemes, and the calculation the different times, MUST be taken from the notes supplied in class. In specific, figures 7. 8, 7. 9, 7. 10 & 7. 11 MUST be substituted with the ones provided in the supplied notes. Skip: Approximating System Load (page 264) Predicting Wait Time for FCFS (page 267) 9

Synchronization Memory Management Prof Aiman Hanna Department ofSynchronization Memory Management Prof Aiman Hanna Department of
Data Compression Prof Aiman Hanna Department of ComputerData Compression Prof Aiman Hanna Department of Computer
Making Connections Prof Aiman Hanna Department of ComputerMaking Connections Prof Aiman Hanna Department of Computer
Highlevel Synchronization Prof Aiman Hanna Department of ComputerHighlevel Synchronization Prof Aiman Hanna Department of Computer
Data Integrity Prof Aiman Hanna Department of ComputerData Integrity Prof Aiman Hanna Department of Computer
Analog Digital Signals Prof Aiman Hanna Department ofAnalog Digital Signals Prof Aiman Hanna Department of
Basic Synchronization Principles Continue Prof Aiman Hanna DepartmentBasic Synchronization Principles Continue Prof Aiman Hanna Department
Connecting Networks Prof Aiman Hanna Department of ComputerConnecting Networks Prof Aiman Hanna Department of Computer