ULTRIX Performance Management Guide

This ULTRIX Performance Management Guide (December 1991, for ULTRIX Version 4.2A or higher) provides comprehensive information and guidelines for system managers and engineers to tune the ULTRIX operating system for improved performance. Tuning is defined as adjusting, monitoring, and manipulating system parameters, subsystems, and resources that affect overall computer system performance.

The guide is structured into a logical flow:

1. Overview of Subsystems: It introduces the major areas of the ULTRIX operating system that impact performance: the File System, Process Control and Scheduling, Memory Management, the I/O Subsystem, Networking, and Interprocess Communications. For each, it explains its components, functions, and how it relates to overall system performance.
2. Monitoring Tools: It details various ULTRIX commands and utilities (e.g., vmstat, iostat, netstat, ps, df, ipcs, ping, newfs, tunefs, chpt, and system exercisers like dskx, fsx, memx, shmx, cmx, lpx, mtx, netx) that can be used to gather real-time or historical data on system status and resource usage.
3. Diagnosis of Constraints: The document then guides users on how to interpret the data collected by these tools to identify specific performance problems or resource bottlenecks within each subsystem (e.g., disk-bound or swap-bound file systems, excessive paging/swapping, CPU saturation, process table shortages, or network bottlenecks).
4. Tuning Strategies: Finally, it provides practical examples and recommendations for optimizing performance through adjustments to the system configuration file, reorganizing file systems, changing disk partition sizes, adding swap space, modifying buffer cache sizes, adjusting process priorities, and configuring network and interprocess communication parameters.

The guide emphasizes that tuning is an iterative process of experimentation and relies on system understanding and objective measurement rather than rigid rules. It is primarily aimed at experienced users but also offers foundational information for novices.