Course Code: 932
Length: 5 days

This course presents the components, structures and mechanisms of the OpenVMS Alpha operating system. It is intended for those students without significant programming backgrounds, who want a better understanding of how OpenVMS works.

This course features:

Topics covered will allow students to develop a better understanding of general troubleshooting and performance, based on a fundamental understanding of how OpenVMS works.

The course will provide a general overview of system mechanisms, such as Interrupt Priority Level, Spinlocks, CPU context, access modes, etc.

Students will be able to use the System Dump Analyzer on a live system to examine the data structures that form the Operating System. The dynamics of the Operating System will be explored through changes to data structures visible through SDA.

The focus will be on the three major subsystems of OpenVMS: Process and Scheduling, Memory Management, and I/O. We will try at all times to develop a big picture understanding of the internals of OpenVMS. To apply these concepts we will explore process hangs in a variety of resource wait states.

Who Should Attend

OpenVMS System Managers and Application Programmers

Prerequisites

Before taking this course, students should be able to demonstrate:

• Advanced System Management Skills
• A general understanding of Operating System Concepts
• An understanding of Binary and Hexadecimal numerical representation

Benefits of Attending this Class

Upon completion of this course, students will be able to:

• Use the System Dump Analyzer (SDA) to examine data structures and system data cells
• Describe process and supporting process-related data structures
• Describe the data structures that constitute a process and examine them using SDA
• Describe the processing and roles of interrupts and exceptions
• Describe the roles of the following synchronization techniques: ASTs, timers, and locks
• Describe the dynamics and data structures associated with image activation
• Develop a better understanding of the metrics associated with paging
• Describe the image activation process and its relationship to paging
• Describe the working set algorithms under OpenVMS
• Properly size process working sets
• Interpret paging metrics
• Properly set working set adjustment related SYSGEN parameters
• Analyze the layout of an image file
• Track page file usage
• Describe the layout and functions of data structures within the I/O database
• Describe the OpenVMS scheduling mechanism and change system parameters that affect scheduling
• Describe the reasons for processes entering and leaving wait states
• Analyze process and system stalls caused by process resource wait states.

Course Contents

GENERAL OPERATING SYSTEM CONCEPTS

OpenVMS Access Modes
Registers and Context
Stacks
Linked Lists
Interrupt Priority Level and Spinlock Overview
Structured Definition Language

INTRODUCTION TO SDA

SDA Requirements and Uses
Commonly Used Commands
Symbols and Operators
CLUE

THE PROCESS

The Process
Data Structures Overview
Software Process Control Block (PCB)
Job Information Block (JIB)
Process Header (PHD)
Thread Concepts/Controls
Kernel Thread Block (KTB)
Floating Point Register Execution Data (FRED)
Thread ID
Virtual Address Space
PCB Vector Table
KTB Vector Table
PIDs and PCBs

OPENVMS SCHEDULING

Thread Wait States
Common Event Flag Wait Queue
Computable Queues (also COMO)
The Scheduler
Boosting Software Priority
Report System Event (RSE)
Quantum End and Wait State Activities

GENERAL MECHANISMS AND SYNCHRONIZATION

Dynamic Memory Mechanisms (Pool)
Asynchronous System Traps
Timer Queue Entries
Synchronization Using the Lock Manager

MEMORY MANAGEMENT: IMAGE ACTIVATION

Memory Management Concepts
Virtual Address Translation
The Process Header
Creation of an Image File from Source Code
Image Activation
Layout of Virtual Address Space
Layout of Process Section Table
Layout of Working Set
Clustering on Pagefault Reads

Memory Management: Process Paging Dynamics and Structures

Evolution of a Page Table Entry
Image and Process Sections
The Working Set List and Automatic Working Set Adjustment
The PFN Database
The Free Page List
The Modified Page List
Determining Pagefile Usage
Interpreting the $MONITOR Page Display
Swapper and Memory Reclamation Related Activities

Memory Management: Global Paging

Shared Images and Global Sections
Global Section Data Structures
Global Section Dynamics
Known Files
Listing Known File Data Structures
The System Header

I/O: CHANNEL ASSIGNMENT AND DRIVER ROUTINES

Paths from I/O Initiation to Completion
Channel Assignment
$QIO and Function Decision Table Routine Processing
Data Structure Support for $QIO and FDT Routines
Start I/O Processing
I/O Post Processing

RESOURCE WAIT STATES

Resource Wait States
RWAST Waits
RWMBX Waits
RWMPB Waits
RWSCS Waits
MUTEX Waits

OpenVMS INTERNALS "BIG PICTURE"