1. Basic Synchronization Principles (Continue)
Operating Systems
Basic Synchronization Principles
(Continue)
1) These notes are © Aiman Hanna. All copyrights reserved. For more information please to:
2) These notes are also based on: Operating Systems, 3rd edition by Garry Nutts, published by Addison Wesley, ISBN-10: | ISBN-13: These notes still totally enforce all copyrights for Nutts/ Addison Wesley. For more information on these rights, please refer to the original publication of the book.
3) VERY IMPORTANT: These notes are neither complete nor sufficient to study for the course. They are merely given so that you can follow the covered subjects. You should NEVER depend solely on these notes for your study.
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© Dr. Aiman Hanna
Department of Computer Science Concordia University Montreal, Canada
Data Communications & Computer Networking, by: Aiman Hanna

2. Classical Synchronization Problems
Bounded Buffer Problem
Different solutions were discussed, in which some failed
Reasons behind failures

3. Classical Synchronization Problems
Reader-Writer Problem
Different solutions were discussed, in which some failed
Reasons behind failures

4. Difficulties with Semaphores
How semaphores can be implemented
Possible failure if implementation is based on Disable and Enable Interrupts
Need to depend on HW instead of SW to implement semaphores (will be discussed in details during week 5)

5. Difficulties with Semaphores
Different implementation of V() operation
Passive and Active V()
Advantages and disadvantages of each

6. Difficulties with Semaphores
After all, semaphores are powerful and capable of solving synchronization and CS problems, BUT…
Solutions may become very difficult, especially when the problems are relatively bigger/more complicated

7. Difficulties with Semaphores
So, what can be done? Are there any alternatives?
High-level synchronization would provide an alternative to semaphores (this is the subject of Chapter 9, which will covered starting week 5)

8. Where is this week coverage in the textbook?
Chapter 8:
Sections 8.3 (starting from page 310) & 8.4.
Note: Figure 8.17 and Figure 8.25 will be covered during week 5.