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Questions and Answers
What is the primary idea behind all solutions to protect critical regions?
What is the primary idea behind all solutions to protect critical regions?
What is a major drawback of disabling interrupts on uniprocessors?
What is a major drawback of disabling interrupts on uniprocessors?
What makes atomic hardware instructions useful?
What makes atomic hardware instructions useful?
What is the simplest software tool used to solve the critical section problem?
What is the simplest software tool used to solve the critical section problem?
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What is the main purpose of acquire() and release() calls?
What is the main purpose of acquire() and release() calls?
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Why are acquire() and release() calls required to be atomic?
Why are acquire() and release() calls required to be atomic?
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What is a spinlock?
What is a spinlock?
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What is the main advantage of using semaphores over mutex locks?
What is the main advantage of using semaphores over mutex locks?
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What is the purpose of a boolean variable in a mutex lock?
What is the purpose of a boolean variable in a mutex lock?
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Why are hardware atomic instructions used to implement mutex locks?
Why are hardware atomic instructions used to implement mutex locks?
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Study Notes
Process Synchronization
- Process synchronization is necessary to maintain data consistency in concurrent execution environments.
The Critical-Section Problem
- The critical-section problem arises when multiple processes access shared data concurrently, leading to data inconsistency.
- The problem involves designing a protocol to ensure that only one process can execute its critical section at a time.
Solution to Critical-Section Problem
- The solution must satisfy three conditions: • Mutual Exclusion: no two processes can execute their critical sections simultaneously. • Progress: a process waiting to enter its critical section will eventually do so. • Bounded Waiting: a limit exists on the number of times other processes can enter their critical sections before the waiting process enters its critical section.
Critical Section Handling in OS
- Two approaches to critical-section handling exist, depending on whether the kernel is preemptive or non-preemptive.
- Preemptive kernel: allows preemption of a process when running in kernel mode.
- Non-preemptive kernel: runs until it exits kernel mode, blocks, or voluntarily yields CPU.
Synchronization Hardware
- Many systems provide hardware support for implementing critical section code using locks.
- Uniprocessors can disable interrupts to protect critical regions, but this approach is inefficient on multiprocessor systems.
Mutex Locks
- Mutex locks are software tools that solve the critical section problem.
- A mutex lock protects a critical section by requiring a process to acquire the lock before entering the critical section and releasing it afterwards.
- Mutex locks can be implemented using hardware atomic instructions, but they require busy waiting, making them spinlocks.
Semaphore
- Semaphore is a synchronization tool that provides more sophisticated ways to synchronize process activities than mutex locks.
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Description
This quiz covers the concepts of process synchronization in Operating Systems, including critical-section problems, Peterson's solution, and synchronization hardware.
