121 lines
7.3 KiB
HTML
121 lines
7.3 KiB
HTML
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<title>Basic performance tuning</title>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Basic performance tuning</h1>
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<div><p>To tune your system's performance, you need to set up your initial
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tuning values, observe the system performance, review the values, and determine
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what to tune.</p>
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<div class="section"><p>To begin tuning performance, you must first set initial tuning
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values by determining your initial machine and user pool sizes. Then, you
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can begin to observe the system performance.</p>
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<p><strong>Set initial tuning values</strong></p>
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<p>Setting
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initial tuning values includes the steps you take to initially configure the
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system pool sizes and activity levels to tune your system efficiently. The
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initial values are based on estimates; therefore, the estimates may require
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further tuning while the system is active. The following steps set the initial
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tuning values:</p>
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<ul><li>Determine initial machine pool size<p><img src="./delta.gif" alt="Start of change" />Tune the machine pool
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to under 10 faults/second. <img src="./deltaend.gif" alt="End of change" /></p>
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</li>
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<li>Determine initial user pool sizes<p><img src="./delta.gif" alt="Start of change" />Tune user pools so that
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the sum of faults for all user pools are less than the number of processors
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times the processors percent busy. For example, in a system with four processors
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running at 50 percent busy (4 * 50 = 200), you would set the faults to less
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than 200 faults/seconds. <img src="./deltaend.gif" alt="End of change" /></p>
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</li>
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</ul>
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<p><strong>Observe system performance</strong></p>
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<p>To observe the system performance,
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you can use the <span class="cmdname">Work with System Status (WRKSYSSTS)</span>, <span class="cmdname">Work
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with Disk Status (WRKDSKSTS)</span>, and <span class="cmdname">Work with Active Jobs
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(WRKACTJOB)</span> commands. With each observation period, you should examine
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and evaluate the measurements of system performance against your performance
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goals.</p>
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</div>
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<ol><li class="stepexpand"><span>Remove any irregular system activity. Irregular activities that
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may cause severe performance degradation are, for example, interactive program
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compilations, communications error recovery procedures (ERP), open query file
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(OPNQRYF), application errors, and signoff activity.</span></li>
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<li class="stepexpand"><span>Use the WRKSYSSTS, WRKDSKSTS, and WRKACTJOB commands to display
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performance data. You can also use the Performance Tools command, <span class="cmdname">Work
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with System Activity (WRKSYSACT)</span>, to display performance data.</span></li>
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<li class="stepexpand"><span>Allow the system to collect data for a minimum of 5 minutes.</span></li>
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<li class="stepexpand"><span>Evaluate the measures of performance against your performance goals.
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Typical measurements include:</span> <ul><li>Interactive throughput and response time, available from the WRKACTJOB
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display.</li>
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<li>Batch throughput. Observe the auxiliary input/output (AuxIO) and CPU percentage
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(CPU%) values for active batch jobs.</li>
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<li>Spooled throughput. Observe the auxiliary input/output (AuxIO) and CPU
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percentage (CPU%) values for active writers.</li>
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</ul>
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</li>
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<li class="stepexpand"><span>If you observe performance data that does not meet your expectations,
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tune your system based on the new data. Be sure to:</span> <ul><li>Measure and compare all key performance measurements.</li>
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<li>Make and evaluate adjustments one at a time.</li>
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</ul>
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</li>
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</ol>
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<div class="section"><p><strong>Review performance</strong></p>
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<p>Once you have set good tuning values,
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you should periodically review them to ensure your system continues to do
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well. Ongoing tuning consists of observing aspects of system performance and
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adjusting to recommended guidelines.</p>
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<p>To gather meaningful statistics,
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you should observe system performance during typical levels of activity. For
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example, statistics gathered while no jobs are running on the system are of
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little value in assessing system performance. If performance is not satisfactory
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in spite of your best efforts, you should evaluate the capabilities of your
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configuration. To meet your objectives, consider the following:</p>
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<ul><li>Processor upgrades</li>
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<li>Additional storage devices and controllers</li>
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<li>Additional main storage</li>
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<li>Application modification</li>
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</ul>
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<p>By applying one or more of these approaches, you should achieve your
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objectives. If, after a reasonable effort, you are still unable to meet your
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objectives, you should determine whether your objectives are realistic for
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the type of work you are doing.</p>
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<p><strong>Determine what to tune</strong> </p>
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<p>If
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your system performance has degraded and needs tuning, you will need to identify
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the source of the performance problem and to make specific corrections.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahxtune.htm" title="When you have identified a performance problem, you will want to tune the system to fix it.">Tune performance</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rzahxresearchparent.htm" title="There are many options available to help you identify and resolve performance problems. Learn how to use the available tools and reports that can help you find the source of the performance problem.">Research a performance problem</a></div>
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</div>
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