EECS 482 Final Flashcards

Questions and Answers

What abstractions does the OS provide regarding memory management?

Virtual Memory, Address Independence, Protection, Sharing

What is the difference between Uni and Multi programming?

Multiple processes in physical memory space (correct)

Only one process in physical memory space at a time (correct)

Only managed languages are used

It is related to static address translation

What type of address translation happens at compile time?

Static

What is the early dynamic address translation mechanism that doesn't allow sharing?

Base and Bounds Signup and view all the answers

What is a dynamic address translation mechanism that allows sharing?

Segmentation Signup and view all the answers

What is the dynamic address translation mechanism with fixed segment sizes?

Paging Signup and view all the answers

What is the best way to speed up paging?

TLB (Translation Lookaside Buffer) caching Signup and view all the answers

What happens when many processes are using all of their address space?

Thrashing Signup and view all the answers

What are two solutions to thrashing?

Buy more RAM or run fewer processes at once Signup and view all the answers

What is the operating abstraction responsible for managing translation data?

Kernel Signup and view all the answers

What is the best way to increase exec() performance?

Memory Mapped Files Signup and view all the answers

What is the best way to increase multi-threaded server performance?

Thread pools Signup and view all the answers

What are the factors affecting disk performance?

Queueing request, positioning, access Signup and view all the answers

What is the efficiency formula for disk transfers in LaTeX?

T_transfer / (T_transfer + T_pos) Signup and view all the answers

What are three disk scheduling algorithms?

FCFS, SSTF, SCAN Signup and view all the answers

What method helps improve throughput with processes with many disk-local requests?

Anticipatory scheduling Signup and view all the answers

What is the way to ensure file system consistency across failures?

Careful ordering Signup and view all the answers

What are two methods to make a file system update atomic?

Logging and shadowing Signup and view all the answers

Log operations must be ___________________

Idempotent Signup and view all the answers

What are log structured file systems good for?

RAID and SSD Signup and view all the answers

What are some problems associated with RAID?

More disks increase chance of failure, small files are a bit inefficient Signup and view all the answers

What is the way to improve RAID reliability?

Parity Signup and view all the answers

What is RAID 0 known for?

Striping only, no reliability Signup and view all the answers

What does RAID 1 do?

Mirroring, maintain full copy Signup and view all the answers

What is RAID 5?

Floating parity (complicated) Signup and view all the answers

What is the socket analogy compared to?

Mailbox analogy Signup and view all the answers

Are packet transfers over the internet reliable?

False Signup and view all the answers

What is TCP?

Data reliability transfer mechanism Signup and view all the answers

What design ensures data sent was received successfully?

ACK design Signup and view all the answers

What is the way to handle dropped data packets?

Three identical ACKs in a row Signup and view all the answers

If TCP is sending 150 bytes, how many bytes might the user receive?

1-150 bytes Signup and view all the answers

What is a great flag to use with recv to avoid looping?

MSG_WAITALL Signup and view all the answers

What is a super common network design pattern?

Client-Server Signup and view all the answers

What abstracts network functionality into simple function calls?

RPC (Remote Procedure Calls) Signup and view all the answers

What are the illusion factors of RPC?

Failure, performance, service discovery Signup and view all the answers

What is an easy method for distributed ordering?

Reorder send and receives Signup and view all the answers

What ensures partial ordering in a distributed system?

Lamport Happens Before Signup and view all the answers

What ensures full ordering in a distributed system?

Lamport Clocks Signup and view all the answers

What does any operation do in Lamport's system?

increments clock Signup and view all the answers

What is the best way to speed up client-server file systems?

Client-Side Caching Signup and view all the answers

What is the term for transferring the sole copy of a file to the client?

Migration Signup and view all the answers

What involves creating an additional copy of a file at the client?

Replication Signup and view all the answers

What manages concurrency with three states?

Pessimistic concurrency control Signup and view all the answers

What describes concurrency control with no states?

Optimistic concurrency control Signup and view all the answers

What relates to maintaining consistency in file systems?

Consistency in operations Signup and view all the answers

What is advisable when dealing with file system problems?

Draw pictures Signup and view all the answers

What should you read very carefully in search problems?

Search condition Signup and view all the answers

Study Notes

Virtual Memory and Memory Management

Offers abstractions like Address Independence, Protection, and Sharing.
Integral for efficient process handling and resource allocation.

Uni vs Multi Programming

Single process operation in memory leads to simpler management.
Multi-programming enhances CPU utilization by running multiple processes concurrently.

Static Address Translation

Performed at compile time; limits flexibility for dynamic checks, particularly in C language.

Base and Bounds

Early dynamic address translation method.
Prevents memory sharing and suffers from external fragmentation issues.

Segmentation

Allows flexible memory allocation with variable-sized address ranges.
Facilitates sharing among processes, but can lead to fragmentation.

Paging

Implements fixed-size memory blocks for efficient address translation.
Simplifies memory management, enabling faster access and performance.

TLB (Translation Lookaside Buffer)

Essential caching mechanism to accelerate paging operations.

Thrashing

Results from excessive paging when memory resources are overcommitted.
Causes significant performance degradation due to constant page transfers.

Thrashing Solutions

Solutions include increasing RAM or reducing the number of active processes.

Kernel

Core OS component managing memory translation and handling page faults through traps.

Memory Mapped Files

Method to boost performance of exec() calls by mapping file content directly into memory.

Thread Pools

Strategy to enhance multi-threaded server performance through pre-allocated threads.

Disk Performance Factors

Influenced by queueing requests, disk positioning, and access patterns.

Disk Transfer Efficiency

Calculated using the formula T_transfer / (T_transfer + T_pos).

Disk Scheduling Algorithms

First-Come, First-Served (FCFS), Shortest Seek Time First (SSTF), and SCAN define strategies for optimizing disk access.

Anticipatory Scheduling

Improves disk throughput by anticipating future requests and optimizing server responses.

File System Consistency

Ensured through careful ordering to maintain integrity during outages or failures.

Atomic File System Updates

Achieved through techniques such as logging and shadowing.

Idempotency in Logs

Essential feature for ensuring that log operations can be repeatedly applied without unintended effects.

Log Structured File Systems

Particularly effective in environments utilizing RAID and SSD configurations.

RAID Challenges

Increased number of disks raises failure risks; small file handling can be inefficient.

RAID Reliability Enhancement

Parity is implemented to improve data reliability in RAID setups.

RAID Types

RAID 0: Focus on performance without data redundancy.
RAID 1: Offers full redundancy through mirroring.
RAID 5: Includes floating parity to balance performance and reliability.

Socket Communication

Comparable to a mailbox analogy; encapsulates data transfer protocols.

Internet Packet Transfer Reliability

Generally unreliable, leading to potential data loss during transmission.

TCP Mechanism

Implements reliability through acknowledgments (ACKs) to ensure successful data transfers.

ACK Design

Uses acknowledgment packets to verify successful receipt of data.

Handling Dropped Packets

Sending three identical ACKs consecutively helps mitigate data loss.

TCP Data Segmentation

If transmitting 150 bytes, the user may receive between 1 to 150 bytes.

MSG_WAITALL Flag

Utilization with recv to receive complete message data without looping.

Client-Server Architecture

A prevalent design pattern for networked applications managing resources and requests.

RPC (Remote Procedure Calls)

Abstracts network interactions into function calls for easier programming.

RPC Illusions

Factors include challenges of failure, performance, and service discovery.

Distributed Ordering

Achieved by reordering send and receive operations across systems.

Lamport's Happens Before

Establishes a mechanism for ensuring partial order in distributed systems.

Lamport Clocks

Method for maintaining a total order of events within distributed computing.

Incrementing Clocks in Lamport

Every operation recorded increments the clock to reflect event sequence.

Client-Side Caching

Improves performance in client-server file systems through localized data storage.

File Migration

Process of transferring a single copy of a file to the client for access.

File Replication

Creates additional file copies to ease access but complicates concurrent write handling.

Concurrency Control Mechanisms

Pessimistic control manages access states, while optimistic allows unregulated access with conflict resolution.

Project 3 Headspace

Focus on virtual and physical memory identification and handling dirty page transitions.

Project 4 Headspace

Emphasizes consistency, visual aids in problem-solving, and careful reading of search conditions.

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Description

Test your knowledge on important concepts in operating systems, particularly focusing on memory management and programming paradigms. This quiz covers virtual memory, process handling, and static address translation. Perfect for reviewing key ideas before your EECS 482 final exam.