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Questions and Answers
What is the primary function of the I/O subsystem?
What is the primary function of the I/O subsystem?
What is the main goal of Storage Management?
What is the main goal of Storage Management?
What is the process of temporarily storing data during I/O operations?
What is the process of temporarily storing data during I/O operations?
What is the term for the overlapping of output of one job with input of another job?
What is the term for the overlapping of output of one job with input of another job?
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What is the purpose of a device driver?
What is the purpose of a device driver?
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What is the term for moving data between levels of storage hierarchy?
What is the term for moving data between levels of storage hierarchy?
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What is the term for the mechanism that ensures all CPUs have the most recent value of a datum in their cache?
What is the term for the mechanism that ensures all CPUs have the most recent value of a datum in their cache?
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What is the responsibility of the operating system in connection with process management?
What is the responsibility of the operating system in connection with process management?
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What is the term for the protection of the system against internal and external attacks?
What is the term for the protection of the system against internal and external attacks?
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What is the purpose of free-space management in mass-storage management?
What is the purpose of free-space management in mass-storage management?
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Study Notes
Multiprocessor Systems
- Increased throughput can be achieved through multiprocessor systems.
- Two types of multiprocessor systems:
- Asymmetric Multiprocessing
- Symmetric Multiprocessing
Clustered Systems
- Like multiprocessor systems, but multiple systems work together.
- Usually share storage via a storage-area network (SAN).
- Provides a high-availability service that survives failures.
- Two types of clustering:
- Asymmetric clustering: one machine in hot-standby mode.
- Symmetric clustering: multiple nodes running applications, monitoring each other.
Operating System Structure
- Multiprogramming is needed for efficiency.
- A subset of total jobs in the system is kept in memory.
- One job is selected and run via job scheduling.
- When a job has to wait (e.g. for I/O), the OS switches to another job.
- Timesharing (multitasking) is a logical extension of multiprogramming.
- Response time should be less than 1 second.
- Each user has at least one program executing in memory (a process).
- If several jobs are ready to run at the same time, CPU scheduling is used.
- If processes don't fit in memory, swapping moves them in and out to run.
- Virtual memory allows the execution of processes not completely in memory.
Process Management
- A process is a program in execution.
- Process management activities:
- Creating and deleting processes
- Suspending and resuming processes
- Providing mechanisms for process synchronization
- Providing mechanisms for process communication
- Providing mechanisms for deadlock handling
Interrupt Handling
- The operating system preserves the state of the CPU by storing registers and the program counter.
- Determines which type of interrupt has occurred.
- Separate segments of code determine what action should be taken for each type of interrupt.
- Interrupt handling involves:
- Polling
- Vectored interrupt system
I/O Structure
- Two types of I/O structures:
- Wait instruction idles the CPU until the next interrupt.
- System call – request to the operating system to allow the user to wait for I/O completion.
Storage Hierarchy
- Storage systems are organized in a hierarchy.
- Cache: copying information into faster storage system.
- Main memory: only large storage media that the CPU can access directly.
- Secondary storage: extension of main memory that provides large nonvolatile storage capacity.
Computer-System Architecture
- Most systems use a single general-purpose processor.
- Multiprocessors systems are growing in use and importance.
- Advantages of multiprocessors:
- Increased throughput
- Economy of scale
- Increased reliability – graceful degradation or fault tolerance
Memory Management
- Memory management activities:
- Keeping track of which parts of memory are currently being used and by whom.
- Deciding which processes and data to move into and out of memory.
- Allocating and deallocating memory space as needed.
Storage Management
- OS provides a uniform, logical view of information storage.
- Abstracts physical properties to logical storage unit - file.
- File-System management:
- Creating and deleting files and directories.
- Primitives to manipulate files and directories.
- Mapping files onto secondary storage.
- Backup files onto stable storage media.
Mass-Storage Management
- Proper management of mass storage is of central importance.
- OS activities:
- Free-space management.
- Storage allocation.
- Disk scheduling.
- Some storage need not be fast, such as tertiary storage.
Performance of Various Levels of Storage
- Movement between levels of storage hierarchy can be explicit or implicit.
- Importance of cache coherency in hardware.
I/O Subsystem
- I/O subsystem responsible for:
- Memory management of I/O, including buffering, caching, and spooling.
- General device-driver interface.
- Drivers for specific hardware devices.
Protection and Security
- Protection: any mechanism for controlling access of processes or users to resources defined by the OS.
- Security: defense of the system against internal and external attacks.
- Systems distinguish among users to determine who can do what.
- User identities (user IDs, security IDs) include name and associated number.
- Access control includes user ID, group ID, and privilege escalation.
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Description
This quiz covers the concepts of multiprocessing in operating systems, including asymmetric and symmetric multiprocessing, and its benefits such as increased throughput and reliability.
