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AIX Versions 3.2 and 4 Performance Tuning Guide

Using PerfPMR for Performance Diagnosis

The PerfPMR package was developed to ensure that reports of suspected performance problems in AIX were accompanied by enough data to permit problem diagnosis by IBM. This makes the shell scripts in PerfPMR useful to other performance analysts as well. PerfPMR is an optionally installable part of the AIX Version 4 Base Operating System. It is located in /usr/sbin/perf/pmr. See the discussion in "Installing AIX Version 4 PerfPMR". A version of PerfPMR is also available for AIX Version 3.2.5. See "Obtaining and Installing AIX Version 3.2.5 PerfPMR".

The script perfpmr is the highest-level script of the package, but it collects data, such as configuration information, that a local performance analyst probably knows already. The lower-level script monitor collects a coordinated set of performance information for a specified number of seconds and summarizes the data. The syntax of monitor is:

monitor seconds [-n] [-p]

The seconds parameter must be at least 60. If seconds is 600 or less, the interval for the periodic reports is 10 seconds; otherwise, the interval is 60 seconds. The -n flag suppresses collection of netstat and nfsstat data. The -p flag suppresses collection of process-profile data (see below). The monitor script should not be run at the same time as any other operation that uses the system trace facility.

A single monitor request creates:

Check before You Change

One particularly important use of the PerfPMR package is the creation of a configuration and performance baseline prior to a significant change in system hardware or software. Just as you probably back up critical files before such a change, you should make a record of the configurations and the performance they were providing. If a performance degradation should occur after the change, you will have detailed data that will let you perform a rigorous before-and-after analysis of the system.

To get the most complete data possible, you should run:

$ perfpmr 3600

during the busiest hour of the day. The output files from this measurement run will appear in directory /var/perf/tmp. (If you are running on a pre-Version 4 system, the output files will appear in the current working directory.) Be sure to move these files to a safe haven before beginning the configuration change.

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