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AIX Versions 3.2 and 4 Performance Tuning Guide

Appendix A. AIX Performance Monitoring and Tuning Commands

Performance tools for the AIX environment fall into two general categories: those that tell you what is going on and those that let you do something about it. A few do both. This appendix lists these performance-related commands. Many of them are discussed in the chapters on tuning specific aspects of the system. The details of the syntax and functions of most of these commands are documented in the AIX Version 4.3 Commands Reference. The schedtune, pdt_config, pdt_report, and vmtune commands are documented later in this appendix.

Some of the performance-related commands are packaged as part of the Performance Toolbox for AIX (PTX), rather than the AIX Base Operating System. Those commands are identified with (PTX). You can determine whether the PTX tools have been installed with:

$ lslpp -lI perfagent.tools

If this package is listed as AVAILABLE , the PTX tools can be used.

The following lists summarize the performance-related commands:

Performance Reporting and Analysis Commands

These tools give you information on the performance of one or more aspects of the system or on one or more of the parameters that affect performance.

Command Function
bf, bfrpt
                          Provides detailed reports of the memory-access patterns of applications.
                           Reports emulation instruction counts.
                           Uses the trace facility to report on the I/O activity of physical volumes, logical volumes, individual files, and the Virtual Memory Manager.
                           Displays the physical or logical placement of the blocks that constitute a file within the physical or logical volume on which they reside.
                           Reports the flow of control among the subroutines of a program and the amount of CPU time consumed by each subroutine.
                          Displays utilization data for:
  • Terminals
  • CPU
  • Disks
                           Displays information about kernel lock contention.
                          Displays attributes of the system that affect performance, such as:
  • Size of the caches
  • Size of real memory
  • Maximum number of pages in the block I/O buffer cache
  • Maximum number of kilobytes of memory allowed for mbufs
  • High- and low-water marks for disk-I/O pacing
                          Displays information about a logical volume.
                           Uses the trace facility to report on network activity, including:
  • CPU consumption
  • Data rates
  • Response time
                          Displays a wide variety of configuration information and statistics on communications activity, such as:
  • Current status of the mbuf pool
  • Routing tables
  • Cumulative statistics on network activity
                          Displays (or changes) the values of NFS options
                          Displays statistics on Network File System (NFS) and Remote Procedure Call (RPC) server and client activity
                          Displays (or changes) the values of network options, such as:
  • Default send and receive socket buffer sizes
  • Maximum total amount of memory used in mbuf and cluster pools
                          Starts, stops, or changes the parameters of the Performance Diagnostic Tool.
                          Generates a PDT report based on the current historical data.
                          Displays statistics and status information about the processes in the system, such as:
  • Process ID
  • I/O activity
  • CPU utilization
                          Displays statistics on operating-system activity such as:
  • Directory accesses
  • Read and write system calls
  • Forks and execs
  • Paging activity
                          Displays (or changes) the values of VMM memory-load-control parameters, the CPU-time-slice duration, and the paging-space-low retry interval.
                          Displays (or changes) system-management parameters.
                           Supports the entry and exit instrumentation of executable programs without requiring access to the source code of the executable.
                           Reports on the status of memory at system, process, and segment levels
                           Records and counts system calls
                          Prints the elapsed and CPU time used by the execution of a command
                            Uses the trace facility to report the CPU consumption of kernel services, library subroutines, application-program modules, and individual lines of source code in the application program
                          Writes a file that records the exact sequence of activities within the system
                          Displays VMM data, such as:
  • Number of processes that are dispatchable or waiting
  • Page-frame free-list size
  • Page-fault activity
  • CPU utilization
                          Displays (or changes) the Virtual Memory Manager page-replacement algorithm parameters.

Performance Tuning Commands

The following tools allow you to change one or more performance-related aspects of the system.

Command Function
                           Optimizes executable files for a specific workload.
                          Changes (or displays) the values of NFS options
                          Executes a command at a specified priority
                          Changes (or displays) the values of network options
                          Changes the priority of running processes
                          Reorganizes elements of a volume group.
                            Temporarily reduces the effective RAM size of a system to assess the probable performance of a workload on a smaller machine or to ascertain the memory requirement of one element of a workload.
                          Changes (or displays) the values of VMM memory load control parameters, the CPU-time-slice duration, and the paging-space-low retry interval.
                          Changes (or displays) system-management parameters.
                          Changes (or displays) the Virtual Memory Manager page-replacement algorithm parameters.

Related Information

"Commands Overview" in AIX Version 4.3 System User's Guide: Operating System and Devices describes how to read syntax diagrams.

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