Chapter 6
Understanding Critical Sections and Race Conditions
This quiz is designed to test your knowledge on critical sections in operating systems and their impact on concurrent processes. Dive into the intricacies of synchronization mechanisms, memory models, and the architecture of concurrent programming.
Key Topics Covered:
- Mutual Exclusion
- Race Conditions
- Hardware Instructions
- Memory Models
An undesirable situation that occurs when two or more processes access and manipulate data concurrently
Concurrency
Parallelism
Race condition
When one process in its critical section, no other may be in its critical section at the same time
Flase
True
Critical-section problem is
A code segment that can be accessed by only one process at a time
A protocol that the processes can use to synchronize their activity so as to cooperatively share data
A solution to the critical-section problem must satisfy the following 3 requirements
1-Mutual Exclusion 2-Progress 3-Unbounded Waiting
1-Mutual Exclusion 2-Progress 3-Bounded Waiting
1-Starvation 2-Progress 3-Mutual Exclusion
The description of Mutual Exclusion is
If process Pi is executing in its critical section, then no other processes can be executing in their critical sections
If no process is executing in its critical section and there exist some processes that wish to enter their critical section, then only those processes can participate in deciding which will enter its critical section next
A bound must exist on the number of times that other processes are allowed to enter their critical sections after a process has made a request to enter its critical section and before that request is granted
Many kernel-mode processes may be active in the operating system. So, the code implementing an OS (kernel code) is subject to several possible _______
False terminations
Overlappings
Race conditions
What are the two general approaches that are used to handle critical sections in operating systems?
1-Preemptive Kernels 2-Non Preemptive Kernels
1-RollBack 2-Starvation
Which of the following belong to Preemptive Kernels? Multiple answers
Allows preemption of process when running in kernel mode
Allows a kernel-mode process to run until it exits kernel mode, blocks, or voluntarily yields CPU
Specially difficult to design
Not feasible solution for SMP architectures
Essentially free of race conditions on kernel data structures
Makes the system more responsive
Memory model is
An instruction that forces any change in memory to be propagated (made visible) to all other processors
How a computer architecture determines what memory guarantees it will provide to an application program
Memory models are only strongly ordered
True
False
What are hardware instructions?
Commands that allow the operating system to enable or disable some hardware
Instructions that allow us to either test-and-modify the content of a word, or to swap the contents of two words atomically
The test-and-set is an instruction used to
Play with Ghazy's feet
Test a memory location and set a new value as an atomic operation
Write to a memory location and return its old value as a single atomic operation
Which of the following properties belong to the swap and compare instruction
Returns the original value of passed parameter
Set the new value of passed parameter to true
Set the variable value the value of the passed parameter new_value but only if *value == expected is true.
Which of the following is the least complicated way to solve the critical section problem
Test-and-set
Swap and compare
Semaphore
Mutex lock
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