Podcast
Questions and Answers
The Banker's Algorithm uses two key algorithms: the ______ Algorithm and the Resource-request algorithm.
The Banker's Algorithm uses two key algorithms: the ______ Algorithm and the Resource-request algorithm.
Safety
A breach of ______ involves the unauthorized reading of data.
A breach of ______ involves the unauthorized reading of data.
confidentiality
To prevent deadlocks by addressing the 'hold and wait' condition, a process must not ______ other resources when requesting a new one.
To prevent deadlocks by addressing the 'hold and wait' condition, a process must not ______ other resources when requesting a new one.
hold
______ allocation suffers from the disadvantage of requiring numerous I/O operations and disk seeks to locate blocks.
______ allocation suffers from the disadvantage of requiring numerous I/O operations and disk seeks to locate blocks.
A main disadvantage of Access Control Matrices (ACM) is that as the number of files and users increases, the matrix size increases, which may exclude more ______ capacity.
A main disadvantage of Access Control Matrices (ACM) is that as the number of files and users increases, the matrix size increases, which may exclude more ______ capacity.
Flashcards
Prevent Hold and Wait
Prevent Hold and Wait
Ensuring processes don't simultaneously hold resources and wait for others.
Non-preemption
Non-preemption
Resources are taken away from a process.
Segmentation
Segmentation
A memory management scheme supporting the user's view of memory; can cause external fragmentation.
Denial of Service (DOS)
Denial of Service (DOS)
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Breach of Integrity
Breach of Integrity
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Study Notes
- Deadlock prevention involves strategies to ensure that deadlocks do not occur in the system, and the four conditions are mutual exclusion, hold and wait, non-preemption, and circular wait.
Mutual Exclusion
- Addresses the condition where resources are non-shareable.
- Preventative measure: Utilize shareable resources like read-only files.
Hold and Wait
- Addresses the condition where a process holds resources while waiting for others.
- Can cause starvation.
- Prevention: Processes must request all required resources at once or pre-allocate resources.
Non-Preemption
- Addresses the condition where resources cannot be forcibly taken away from a process.
- When hold and wait occurs, all currently held resources are released, and preempted resources are added to processes waiting for them.
Circular Wait
- Addresses the condition where a circular chain of processes exists, each waiting for a resource held by the next process in the chain.
- Prevention involves allowing resource requests in an increasing order.
Deadlock Avoidance
- Two algorithms used are Resource Allocation Graph (RAG) and Banker's Algorithm.
Banker's Algorithm
- Employs a safety algorithm and a resource-request algorithm.
- The resource-request algorithm uses available, allocation, and need parameters.
Segmentation
- Is a memory management scheme that supports the user's view of memory.
- Causes external fragmentation.
Advantages of Access Control Matrix (ACM)
- Easy implementation.
- Works well in systems with few files and users.
Disadvantages of Access Control Matrix (ACM)
- As file and user count increases, the matrix size increases, using more main memory capacity.
- Wasted space due to null entries.
Allocation Methods
- Three types include Contiguous, Linked and Indexed.
Linked Allocation
- Has no external fragmentation.
- Example: 9, 16, 1, 10, 25, -1 (where -1 indicates the end of the chain).
Disadvantages of Linked Allocation
- Location of blocks requires many I/O operations and disk seeks.
- If one pointer is corrupted, it creates reliability issues.
Security Violation Categories
- Five categories: Breach of confidentiality, Breach of integrity, Breach of availability, Theft of service and Denial of Service (DOS).
Breach of Confidentiality
- Unauthorized reading of data.
Breach of Integrity
- Unauthorized modification of data.
Breach of Availability
- Unauthorized destruction of data.
Theft of Service
- Unauthorized use of resources.
Denial of Service (DOS)
- Prevention of legitimate use of a system or resource.
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Description
Deadlock prevention strategies ensure deadlocks do not occur by addressing mutual exclusion, hold and wait, non-preemption, and circular wait conditions. Solutions include utilizing shareable resources, requesting all resources at once, or pre-allocation. Additionally, preempting held resources and imposing an order to prevent circular waits are employed.
