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AIX Versions 3.2 and 4 Performance Tuning Guide
About This Book
This book, the AIX Versions 3.2 and 4 Performance Tuning Guide, provides
information on concepts, tools, and techniques for assessing and tuning
the performance of AIX on RS/6000 systems.
Topics covered include efficient system and application design and implementation,
as well as post-implementation tuning of CPU use, memory use, disk I/O,
and communications I/O. Most of the tuning recommendations were developed
or validated on AIX Version 3.2.5. Some information on AIX Version 4 is
also provided. Information that applies only to AIX Version 4 is so identified
in the text.
The material in this guide is designed
for programmers, system managers, and end users concerned with performance
tuning of AIX systems. You should be familiar with the AIX
operating environment. Introductory sections are included to assist the
less experienced and to acquaint experienced users with AIX performance-tuning
terminology.
This is a major revision of the AIX
Version 3.2 Performance Monitoring and Tuning Guide, including both
changes in organization and new tuning recommendations. Of particular interest
to the performance analyst are the changes in the packaging and content
of the AIX performance tools in AIX Version 4.
AIX Performance Management Structure
There are appropriate tools for each phase
of AIX system performance management. Some of the tools are available from
IBM; others are the products of third parties. The figure
illustrates the phases of performance management in a simple LAN environment
and some of the tools packages that apply in each phase. This tuning guide
also provides information about each phase.
Performance Tools Packages and Their Documentation
The packaging of the performance tools
lets the performance analyst install on any given system only those tools
that are required to monitor and tune that system. The packages and their
main functions are described in the following sections.
BEST/1
BEST/1 is a capacity-planning
tool that uses queuing models to predict the performance of a given configuration
when processing a specific workload. The prediction can be based on:
- workload descriptions derived from an
application design, or
- workload data acquired by monitoring existing
systems.
BEST/1 has three main components:
Collect |
Collects detailed information about the processing of a workload by
an existing system. |
Analyze |
Transforms the detailed information into reports and a queuing model
of the workload-processing activity. |
Predict |
Uses the queuing model to estimate the performance effects of changes
in the workload or the configuration. |
BEST/1 for UNIX is a product of BGS Systems,
Inc. BGS Systems can be reached at 1-800-891-0000 (in the US).
AIX Performance Diagnostic Tool (PDT)
The Performance
Diagnostic Tool, which is an optionally installable component of AIX
Version 4, assesses the configuration of the system and tracks trends in
resource use. If PDT detects an actual or potential performance problem,
it reports the situation to the system administrator. This book contains
the primary, detailed documentation of the functions of
PDT.
AIX Base Operating System (BOS)
The AIX Base Operating System contains
a number of monitoring and tuning tools that have historically been part
of UNIX systems or are required to manage the implementation-specific features
of AIX. The BOS functions and commands that are most important to performance
analysts are:
iostat |
Reports CPU and I/O statistics. |
lsattr |
Displays the attributes of devices. |
lslv |
Displays information about a logical volume or the logical volume allocations
of a physical volume. |
netstat |
Displays the contents of network-related data structures. |
nfsstat |
Displays statistics about Network File System (NFS) and Remote Procedure
Call (RPC) activity. |
nice |
Runs a command at higher- or lower-than-normal priority. |
no |
Displays or sets network options. |
ps |
Displays the status of processes. |
renice |
Changes the priority of one or more processes. |
reorgvg |
Reorganizes the physical-partition allocation within a volume group. |
sar |
Collects and reports or records system-activity information. |
time |
Prints the elapsed execution time and the user and system processing
time attributed to a command. |
trace |
Records and reports selected system events. |
vmstat |
Reports virtual-memory activity and other system statistics. |
The documentation of the AIX BOS commands
is the AIX Commands Reference Manual.
Performance Toolbox (PTX)
The
Performance Toolbox for AIX (PTX) contains tools for local and remote system-activity
monitoring and tuning. This licensed product consists of two main components:
the PTX Manager and the PTX Agent. The PTX Agent is available as a separate
licensed product called the Performance Aide for AIX. The figure
shows a simplified LAN configuration in which the PTX Manager is being
used to monitor the activity of several systems.
The main purpose of the PTX Manager is
to collect and display data from the various systems in the configuration.
The primary program for this purpose is xmperf. The primary program
used by the Agent to collect and transmit data to the Manager is xmservd.
In addition to the main PTX components,
in AIX Version 4 both the Performance Toolbox for AIX and the Performance Aide for AIX
licensed products include a set of separate monitoring and tuning tools,
most of which are part of the AIX Version 3.2.5 Base Operating System:
fdpr |
Optimizes an executable program for a particular workload. |
filemon |
Uses the trace facility to monitor and report the activity of the AIX
file system. |
fileplace |
Displays the placement of a file's blocks within logical or physical
volumes. |
lockstat |
Displays statistics about contention for kernel locks. |
netpmon |
Uses the trace facility to report on network I/O and network-related
CPU usage. |
rmss |
Simulates systems with various sizes of memory for performance testing. |
svmon |
Captures and analyzes information about virtual-memory usage. |
syscalls |
Records and counts system calls. |
tprof |
Uses the trace facility to report CPU usage at module and source-code-statement
levels. |
bf |
Reports memory access patterns of processes (AIX Version 4 only). |
stem |
Permits subroutine-level entry/exit instrumentation of existing executables
(AIX Version 4 only). |
The primary documentation of the commands
and functions of PTX is the Performance Toolbox Version 1.2 and 2 for AIX: Guide and Reference, although the syntax descriptions
of the tools listed above are documented in the AIX Version 4.3 Commands Reference. Use
of the listed commands is incorporated in various diagnosis and tuning
scenarios in this book.
AIX Performance PMR Data Collection Tool
(PerfPMR)
The AIX Performance PMR Data Collection
Tool (PerfPMR) package is used to collect configuration and performance
information to accompany a report of a suspected AIX performance defect.
This book contains the primary, detailed documentation of the functions
and use of PerfPMR.
Tools That Are Not Supported in AIX Version
4
The rmap trace data reduction and
reporting program is not supported in AIX Version 4.
How to Use This Book
Overview of Contents
This book contains the following chapters
and appendixes:
- Chapter 1, "Performance Concepts,"
gives an introduction to the basic considerations of performance analysis.
For those who are already experienced in performance tuning, this chapter
will be of interest mainly as a guide to AIX terminology.
- Chapter 2, "AIX Resource Management
Overview," describes the structures and principal algorithms of the
main resource-management components of AIX.
- Chapter 3, "An Introduction to Multiprocessing,"
provides an overview of the performance aspects of multiprocessor systems.
- Chapter 4, "Performance-Conscious
Planning, Design, and Implementation," describes the performance considerations
that should be taken into account in preparation for an application.
- Chapter 5, "System Monitoring and
Initial Performance Diagnosis," explains how to prepare for the detection
of performance problems and the preliminary steps to take when such a problem
is encountered.
- Chapter 6, "Monitoring and Tuning
CPU Use," describes techniques for ensuring that the CPU resource
is being used efficiently.
- Chapter 7, "Monitoring and Tuning
Memory Use," shows how to determine how much real and virtual storage
is being used and how to avoid or detect some common inefficiencies.
- Chapter 8, "Monitoring and Tuning
Disk I/O," explains the dynamics of disk I/O in AIX and how those
dynamics can be affected by user choices.
- Chapter 9, "Monitoring and Tuning
Communications I/O," gives tuning techniques for various forms of
communications I/O.
- Chapter 10, "DFS Performance Tuning,"
describes various parameters of DFS operation that can affect performance.
- Chapter 11, "Performance Analysis
with the Trace Facility," gives an extended explanation of the use
of the trace facility, which is a powerful tool for detailed performance
tuning and also is the base of a number of other tools discussed in this
book.
- Chapter 12, "Performance Diagnostic
Tool (PDT)," describes an AIX Version 4 tool that assesses configurations
for balance and maintains historical performance data to identify performance
trends.
- Chapter 13, "Handling a Possible
AIX Performance Bug," explains the process of reporting, and providing
data about, a possible performance bug in AIX.
- Appendix A, "AIX Performance Monitoring
and Tuning Commands," lists the AIX commands that are
most helpful in carrying out performance monitoring and tuning tasks and
provides detailed documentation of the syntax and functions of the schedtune,
vmtune, pdt_config, and pdt_report commands.
- Appendix B, "Performance-Related
Subroutines," describes several subroutines with performance-related
uses.
- Appendix C, "Cache and Addressing
Considerations," provides a conceptual discussion of the ways in which
caches can affect the performance of programs.
- Appendix D, "Efficient Use of the
ld Command," describes techniques for using the AIX binder.
- Appendix E, "Performance of the Performance
Tools," documents the resource consumption and response time of the
performance tools.
- Appendix F, "Application Memory Management,"
describes the distinction between the original and the current versions
of the malloc and realloc subroutines.
- Appendix G, "Performance Effects
of Shared Libraries," describes the performance advantages and disadvantages
of shared libraries versus nonshared libraries.
- Appendix H, "Accessing the Processor
Timer," describes methods of using the processor timer to compute
elapsed-time values.
- Appendix I, "National Language Support--Locale
versus Speed," explains the effect that use of the AIX National Language
Support facility can have on performance.
- Appendix J, "Summary of Tunable Performance
Parameters in AIX," documents the AIX operational parameters that
can be changed by the user and that have a direct or indirect effect on
performance.
Highlighting
The following highlighting conventions
are used in this book:
Bold |
Identifies commands, subroutines, keywords, files, structures, directories,
and other items whose names are predefined by the system. Also identifies
graphical objects such as buttons, labels, and icons that the user selects. |
Italics |
Identifies parameters whose actual names or values are to be supplied
by the user. |
Monospace
|
Identifies examples of specific data values, examples of text similar
to what you might see displayed, examples of portions of program code similar
to what you might write as a programmer, messages from the system, or information
you should actually type. |
ISO 9000
ISO 9000 registered quality systems were used in the development and manufacturing of this product.
Related Publications
The following books contain information
about or related to performance monitoring:
- AIX and Related Products Documentation Overview, order number SC23-2456.
- AIX Version 4.3 System User's Guide: Operating System and Devices, order number SC23-4121.
- AIX Versions 4.1 and 4.2 System User's Guide: Operating System and Devices, order number SC23-2544.
- AIX Version 3.2 System User's Guide: Operating System and Devices, order number GC23-2522.
- AIX Version 4.3 System Management Guide: Operating System and Devices, order number SC23-4126.
- AIX Versions 4.1 and 4.2 System Management Guide: Operating System and Devices, order number SC23-2525.
- AIX Version 3.2 System Management Guide: Operating System and Devices, order number GC23-2486.
- AIX Version 4.3 System Management Guide: Communications and Networks, order number SC23-4127.
- AIX Versions 4.1 and 4.2 System Management Guide: Communications and Networks, order number SC23-2526.
- AIX Version 3.2 System Management Guide: Communications and Networks, order number GC23-2487.
- AIX Version 4.3 Commands Reference, order number SBOF-1877.
- AIX Versions 4.1 and 4.2 Commands Reference, order number SBOF-1851.
- AIX Version 3.2 Commands Reference, order number GBOF-1802.
- AIX Version 4.3 General Programming Concepts: Writing and Debugging Programs, order number SC23-4128.
- AIX Versions 4.1 and 4.2 General Programming Concepts, order number SC23-2533.
- AIX Version 3.2 General Programming Concepts, order number SC23-2205.
- AIX Version 4.3 Technical Reference: Base Operating System and Extensions Volume 1, order number SC23-4159.
- AIX Versions 4.1 and 4.2 Technical Reference, Volume 1: Base Operating System and Extensions, order number SC23-2614.
- AIX Version 3.2 Technical Reference, Volume 1: Base Operating System and Extensions, order number SC23-2382.
- AIX Version 4.3 Technical Reference: Base Operating System and Extensions Volume 2, order number SC23-4160.
- AIX Versions 4.1 and 4.2 Technical Reference, Volume 2: Base Operating System and Extensions, order number SC23-2615.
- AIX Version 3.2 Technical Reference, Volume 2: Base Operating System and Extensions, order number SC23-2383.
- Performance Toolbox Version 1.2 and 2 for AIX: Guide and Reference, order number SC23-2625.
- Optimization and Tuning Guide for XL Fortran, XL C and XL C++, order number SC09-1705
- IBM Engineering and Scientific Subroutine Library Guide and Reference, order number SC23-0184.
- RISC System/6000 Technology, order number SA23-2619.
- Comer, D., Internetworking with TCP/IP Vol I, 2nd ed., Englewood Cliffs: Prentice-Hall, 1991.
- Ferrari, D., Serazzi, G., and Zeigner, A., Measurement and Tuning of Computer Systems, New York: Prentice-Hall,1983.
- Lazowska, D., Zahorjan, J., Graham, G., and Sevchik, K., Quantitative System Performance, New York: Prentice-Hall,1984.
- Leffler, McKusick, Karels, and Quarterman, The Design and Implementation of the 4.3 BSD Unix Operating System,
Reading: Addison-Wesley, 1989.
- Smith, C. U., Performance Engineering of Software Systems, Reading: Addison-Wesley, 1990.
- Stern, H., Managing NFS and NIS, Sebastopol, CA: O'Reilly & Associates, Inc., 1992.
Ordering Publications
You can order publications from your
sales representative.
To order additional copies of this book,
use order number SC23-2365.
Use AIX and Related Products Documentation Overview for information
on related publications and how to obtain them.
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Contents |
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