Operating Systems Exam 2 Study Guide

These flashcards cover key vocabulary and concepts related to concurrency, threads, and operating systems.

Concurrency

Multiple tasks making progress during overlapping time periods.

Threads vs Processes

Threads share memory and resources; switching between them is faster than between processes.

Thread Control Block (TCB)

Holds the state of a thread: ID, registers, priority, etc.

Thread Local Storage

Memory each thread uses independently of others.

Thread States

Running, Ready, Waiting/Blocked, Terminated.

Race Condition

When multiple threads access shared data and the result depends on timing.

Determinism

Consistent results that do not depend on timing.

Indeterminism

Results depend on timing.

Thread Trace

A log of the actions taken by a thread during execution.

Critical Section

A block of code that accesses shared resources.

Mutual Exclusion

Ensures one thread in the critical section at a time.

Atomicity

An operation that is all or nothing; it can't be interrupted.

Synchronization Primitives

Tools like locks, semaphores, and condition variables to manage thread timing.

Lock States

Available (unlocked), Acquired (locked).

Tickets Lock

A fair spinlock that lets threads take a number.

Yielding

A thread voluntarily gives up the CPU to others.

Sleeping in Threads

Thread pauses without using CPU until woken.

Cache Coherence Problem

Multiple cores have stale versions of shared data in cache.

Write-through Caching

Writes go to cache and main memory.

Write-back Caching

Writes stay in cache; memory updated later.

System Bus

The communication backbone connecting CPU, RAM, and peripherals.

Approximate Counters

Local counters per core, merged occasionally to a global one.

Granularity of Locks

Coarse locks are simple but slow; fine locks are complex but faster.