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14. Page Faults

This chapter examines the intricacies of page faults and the functioning of memory hierarchies in computer architecture. It explores the mechanisms behind page fault handling, including the processes involved in mapping virtual addresses to physical memory. Additionally, it discusses the roles of translation lookaside buffers (TLBs) and cache systems in enhancing memory access speeds while managing physical and virtual memory interactions.

Sections

Page Faults

This section delves into the mechanism and handling of page faults in computer memory management, detailing how the operating system resolves them.

14.1 Section Overview

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14.1.1 Understanding Page Faults

This section explains the concept of page faults in virtual memory systems and the operations that occur when a page fault occurs.

14.1.2 Operating System's Response to Page Faults

This section discusses the process and implications of page faults in operating systems, including how they are handled and what occurs during these situations.

14.1.3 Updating Page Table after Page Faults

This section explains the process of handling page faults in virtual memory systems, including how the operating system updates the page table and manages memory.

14.1.4 Restarting Instructions after Page Fault

This section explores the process that occurs when a page fault happens, including how the operating system handles it by retrieving the necessary data from secondary memory.

Architecture Example: Intrinsity FastMATH

This section explores page faults and the interaction between virtual and physical memory in the Intrinsity FastMATH architecture.

14.2 Section Overview

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14.2.1 TLB Characteristics

This section discusses the characteristics and functionalities of translation lookaside buffers (TLBs), including page faults and memory management.

14.2.2 Cache Access and Structure

This section explores the mechanisms behind page faults and the caching process in virtual memory systems.

14.2.3 Handling TLB Misses

This section discusses the handling of TLB misses in the context of virtual memory and page faults.

14.2.4 Cycles for TLB Misses

This section explores the handling of TLB misses in the context of page faults and memory access cycles, emphasizing the processes within the operating system.

Memory Hierarchy

This section discusses the concept of memory hierarchy in computer architecture, focusing on page faults, their handling, and the operations of the Translation Lookaside Buffer (TLB).

14.3 Section Overview

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14.3.1 Types of Hits and Misses

The section discusses the occurrence of page faults and the types of hits and misses in a memory hierarchy.

14.3.2 Combinations of Events

This section elaborates on page faults, distinguishing between valid and invalid references, and describes how the operating system responds during such faults.

14.3.3 Possible and Impossible Cases

This section explores page faults, defining valid and invalid references, and the system's response when the required data isn't in memory.

Instruction Timing with Page Faults

This section discusses the concept of page faults, their handling by the operating system, and the timing impact they have on instruction processing.

14.4 Section Overview

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14.4.1 Effective Instruction Time Calculation

This section discusses the mechanism of page faults in memory management and how to calculate effective instruction time.

Learning Objectives

  • Page faults occur when the required data is not found in memory, prompting the OS to manage memory retrieval from secondary storage.

  • TLBs play a crucial role in improving the speed of memory accesses by caching page table entries, thereby reducing access times.

  • The architecture incorporates multiple levels of cache and memory, each capable of experiencing hits or misses during data retrieval.

Key Concepts

Page Fault

An event that occurs when a program attempts to access a page that is not currently mapped to the physical memory, requiring the operating system to retrieve it from secondary storage.

Translation Lookaside Buffer (TLB)

A hardware cache that stores recent translations of virtual memory addresses to physical addresses to speed up memory access.

Cache

A high-speed storage layer that stores copies of frequently accessed data to reduce latency associated with main memory access.

Memory Hierarchy

The structured arrangement of various levels of memory (registers, cache, main memory) that optimizes the performance of data access in a computer system.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting