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OS Ch1-6

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Section 1

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deadlock

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Date created

Mar 1, 2020

Cards (32)

Section 1

(32 cards)

deadlock

Front

a problem occurring when the resources needed by some jobs to finish execution are held by other jobs, which, in turn, are waiting for other resources to become available.

Back

working set

Front

a collection of pages to be kept in main memory for each active process in a virtual memory environment.

Back

real-time system

Front

a computing system used in time-critical environments that require guaranteed response times. Examples include navigation systems, rapid transit systems, and industrial control systems.

Back

Avoidance

Front

Even if the operating system can't remove one of the conditions for deadlock, it can avoid one if the system knows ahead of time the sequence of requests associated with each of the active processes.

Back

firmware

Front

software instructions, or data, that are stored in a fixed or "firm" way, usu- ally implemented on some type of read-only memory (ROM).

Back

mutual exclusion

Front

one of four conditions for deadlock in which only one process is allowed to have access to a resource.

Back

aging

Front

a policy used to ensure that jobs that have been in the system for a long time in the lower-level queues will eventually complete their execution.

Back

virtual device

Front

a dedicated device that has been transformed into a shared device through the use of spooling techniques.

Back

kernel

Front

the primary part of the operating system that remains in random access memory (RAM), and is charged with performing the system's most essential tasks, such as man- aging main memory and disk access.

Back

multiple-level queues

Front

a process scheduling scheme (used with other scheduling algo- rithms) that groups jobs according to a common characteristic.

Back

thrashing

Front

a phenomenon in a virtual memory system where an excessive amount of page swapping back and forth between main memory and secondary storage results in higher overhead and little useful work.

Back

cloud computing

Front

a multifaceted technology that allows computing, data storage and retrieval, and other computer functions to take place via a large network, typically the Internet.

Back

semaphore

Front

is a non-negative integer variable that can be used as a binary signal—a flag. By definition, it can have exactly two positions, no more, no less.

Back

resource holding

Front

one of the four conditions for deadlock in which each process refuses to relinquish the resources it holds until its execution is completed, even though it is not using them because it's waiting for other resources.

Back

livelock

Front

a locked system whereby two or more processes continually block the forward progress of the others without making any forward progress themselves. It is similar to a deadlock except that neither process is blocked or obviously waiting; both are in a continuous state of change.

Back

FIFO anomaly or the Belady Anomaly

Front

an unusual circumstance through which add- ing more page frames causes an increase in page interrupts when using a FIFO page replacement policy.

Back

thread

Front

a portion of a process that can run independently. Multithreaded systems can have several threads running at one time with the same or different priorities.

Back

least recently used (LRU) policy

Front

a page replacement policy that removes from main memory the pages that show the least amount of recent activity.

Back

no preemption

Front

one of four conditions for deadlock in which a process is allowed to hold on to resources while it is waiting for other resources to finish execution.

Back

Device Manager

Front

the section of the operating system responsible for controlling the use of devices. It monitors every device, channel, and control unit and chooses the most efficient way to allocate all of the system's devices.

Back

thread control block (TCB)

Front

a data structure that contains information about the cur- rent status and characteristics of a thread.

Back

cache memory

Front

a small, fast memory used to hold selected data and to provide fast access.

Back

I/O traffic controller

Front

one of the modules of the I/O subsystem that monitors the status of every device, control unit, and channel.

Back

thread status

Front

information stored in the thread control block that indicates the current position of the thread and the resources responsible for this status.

Back

time quantum

Front

a period of time assigned to a process for execution before it is preempted.

Back

Banker's Algorithm

Front

is based on a bank with a fixed amount of capital that operates on the following principles: • No customer will be granted a loan exceeding the bank's total capital. • All customers will be given a maximum credit limit when opening an account. • No customer will be allowed to borrow over the limit. • The sum of all loans won't exceed the bank's total capital.

Back

Job Table (JT)

Front

a table in main memory that contains two values for each active job— the size of the job, and the memory location where its Page Map Table is stored.

Back

virtual memory

Front

a technique that allows programs to be executed even though they are not stored entirely in memory.

Back

multiprogramming

Front

a technique that allows a single processor to process several pro- grams residing simultaneously in main memory, and interleaving their execution by overlapping I/O requests with CPU requests.

Back

internal fragmentation

Front

a situation in which a partition is only partially used by the program; the remaining space within the partition is unavailable to any other job and is, therefore, wasted.

Back

external fragmentation

Front

a situation in which the dynamic allocation of memory creates unusable fragments of free memory between blocks of busy, or allocated, memory.

Back

first-in first-out (FIFO) policy

Front

a page replacement policy that removes from main mem- ory the pages that were first brought in.

Back