180 lines
10 KiB
HTML
180 lines
10 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="System and user defaults system values: Processor multi-tasking" />
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<meta name="abstract" content="Specifies whether processor multi-tasking is on, off, or determined by the system. (QPRCMLTTSK)" />
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<meta name="description" content="Specifies whether processor multi-tasking is on, off, or determined by the system. (QPRCMLTTSK)" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>System and user defaults system values: Processor multi-tasking</title>
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</head>
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<body id="rzakzqprcmlttsk"><a name="rzakzqprcmlttsk"><!-- --></a>
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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">System and user defaults system values: Processor multi-tasking</h1>
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<div><p>Specifies whether processor multi-tasking is on, off, or determined
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by the system. (QPRCMLTTSK)</p>
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<p><span class="uicontrol">Processor multi-tasking</span>, also known as <span class="uicontrol">QPRCMLTTSK</span>,
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is a member of the system and user defaults category of i5/OS™ system
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values. You can work with this system value from the character-based interface;
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it is not in iSeries™ Navigator.
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You can use this system value to specify whether multi-tasking is on, off,
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or system controlled. To learn more, keep reading.</p>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th colspan="2" valign="top" class="firstcol" id="d0e34">Quick reference</th>
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</tr>
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</thead>
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<tbody><tr><th valign="top" class="firstcol" id="d0e38" headers="d0e34 ">Location</th>
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<td valign="top" headers="d0e38 d0e34 ">Character-based interface</td>
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</tr>
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<tr><th valign="top" class="firstcol" id="d0e43" headers="d0e34 ">Special authority</th>
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<td valign="top" headers="d0e43 d0e34 ">All object (*ALLOBJ) and security administrator (*SECADM)</td>
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</tr>
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<tr><th valign="top" class="firstcol" id="d0e48" headers="d0e34 ">Default value</th>
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<td valign="top" headers="d0e48 d0e34 ">System controlled (2)</td>
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</tr>
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<tr><th valign="top" class="firstcol" id="d0e53" headers="d0e34 ">Changes take effect</th>
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<td valign="top" headers="d0e53 d0e34 ">At the next restart of the server</td>
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</tr>
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<tr><th valign="top" class="firstcol" id="d0e58" headers="d0e34 ">Lockable</th>
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<td valign="top" headers="d0e58 d0e34 ">No</td>
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</tr>
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</tbody>
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</table>
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</div>
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<div class="section"><h4 class="sectiontitle">What can I do with this system value?</h4><p>Use this system
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value to control processor multi-tasking. To learn more about how a processor
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does this, see multi-threading.</p>
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<p>This system value has three possible
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values, off (0), on (1), and system controlled (2), and controls whether the
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hardware executes only one or more than one task at a time on a processor.
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The off (0) state means that each processor supports the execution of only
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one task at any moment in time. The states on (1) and system controlled (2)
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allow processors to concurrently execute multiple tasks, with the difference
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being that the system controlled state gives permission to the operating system
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to occasionally limit a processor to executing at most one task. The state
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system controlled is the default value. The value that you specify should
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be based on performance and is workload dependent. By allowing multiple tasks
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per processor, the performance capacity of the system tends to increase. Therefore,
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the system executes more work. On the other hand, by limiting processors to
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execute single tasks, the system tends to allow individual tasks to execute
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faster.</p>
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<p>Changes to the system value do not take effect until the next
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IPL. If you request a change to the state of on (1) or system controlled (2),
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the change takes effect only if the processor hardware supports the concept
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of simultaneous multi-threading (SMT) or hardware multi-threading (HMT). If
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unsupported, the system value change does not take effect.</p>
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<p>On partitioned AS/400<sup>®</sup> 7xx
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and iSeries 8xx
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servers, all partitions inherit the current value from the primary partition.
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Thus, only changes to the system value of the primary partition may become
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effective. In order for changes to take effect, an IPL of the primary partition
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is required. The default value is on (1) if supported by the system hardware.
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Otherwise the default value is off (0).</p>
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<p>On eServer™ i5 servers, the current value
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is partition independent. Thus, changes to the system value of a partition
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may become effective for only that partition. In order for changes to take
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effect, an IPL of only that partition is required. The default value is system
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controlled (2).</p>
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<p>The shipped value is system controlled (2); however,
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the value may change after the first IPL by the system automatically because
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the shipped value is not supported by the hardware on all systems. The shipped
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value may change after the first IPL. The following table describes various
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system environments and what the value will change to after the first IPL:</p>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th valign="top" id="d0e95">Primary/secondary partition attribute</th>
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<th valign="top" id="d0e97">Multi-tasking supported on the hardware</th>
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<th valign="top" id="d0e99"><a href="rzakzqmodel.htm">Server model</a></th>
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<th valign="top" id="d0e102">Value after first IPL</th>
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<th valign="top" id="d0e104">Supported values </th>
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</tr>
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</thead>
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<tbody><tr><td valign="top" headers="d0e95 ">Primary or non-partitioned</td>
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<td valign="top" headers="d0e97 ">Yes</td>
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<td valign="top" headers="d0e99 ">AS/400 7xx
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or iSeries 8xx</td>
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<td valign="top" headers="d0e102 ">1 (on)</td>
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<td valign="top" headers="d0e104 ">On (1) or off (0)</td>
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</tr>
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<tr><td valign="top" headers="d0e95 ">Primary or non-partitioned</td>
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<td valign="top" headers="d0e97 ">No</td>
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<td valign="top" headers="d0e99 ">AS/400 7xx
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or iSeries 8xx</td>
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<td valign="top" headers="d0e102 ">0 (off)</td>
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<td valign="top" headers="d0e104 ">Off (0)</td>
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</tr>
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<tr><td valign="top" headers="d0e95 ">Secondary</td>
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<td valign="top" headers="d0e97 ">Yes</td>
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<td valign="top" headers="d0e99 ">AS/400 7xx
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or iSeries 8xx</td>
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<td valign="top" headers="d0e102 ">Inherits current value from primary partition</td>
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<td valign="top" headers="d0e104 ">On (1) or off (0)</td>
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</tr>
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<tr><td valign="top" headers="d0e95 ">Secondary</td>
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<td valign="top" headers="d0e97 ">No</td>
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<td valign="top" headers="d0e99 ">AS/400 7xx
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or iSeries 8xx</td>
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<td valign="top" headers="d0e102 ">Inherits current value from primary partition</td>
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<td valign="top" headers="d0e104 ">Off (0)</td>
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</tr>
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<tr><td valign="top" headers="d0e95 ">Not applicable <sup>*</sup></td>
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<td valign="top" headers="d0e97 ">Yes</td>
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<td valign="top" headers="d0e99 ">eServer i5</td>
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<td valign="top" headers="d0e102 ">2 (system controlled)</td>
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<td valign="top" headers="d0e104 ">On (1), off (0) or system controlled (2)</td>
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</tr>
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<tr><td valign="top" headers="d0e95 ">Not applicable <sup>*</sup></td>
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<td valign="top" headers="d0e97 ">No</td>
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<td valign="top" headers="d0e99 ">eServer i5</td>
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<td valign="top" headers="d0e102 ">2 (system controlled)</td>
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<td valign="top" headers="d0e104 ">Off (0) or system controlled (2)</td>
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</tr>
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</tbody>
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</table>
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</div>
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<p><span class="uicontrol">*</span> This type of server does not distinguish
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between primary or secondary partitions. Rather it is a partitioned server
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managed by the Hardware Management Console for eServer.</p>
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<div class="note"><span class="notetitle">Note:</span> If you do not know
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whether or not your system's hardware supports multi-tasking, the easiest
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way to find out is to change this system value to on (1). Then, IPL the server.
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If the change takes effect, multi-tasking is supported. If the value does
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not change after the IPL, multi-tasking is not supported by the hardware.</div>
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</div>
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<div class="section"><h4 class="sectiontitle">Where can I get more information about this system value?</h4><p>To
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learn more, go to the system and user defaults system values overview topic.
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If you are looking for a specific system value or category of system values,
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try using the i5/OS system
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value finder.</p>
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<p>In addition, see multi-threading to learn more about processor
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multi-tasking.</p>
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</div>
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</div>
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<div><div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzakzsystemoverview.htm" title="Use system and user defaults system values to control system level values.">System values: System and user defaults overview</a></div>
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<div><a href="../rzahx/rzahxmultithread.htm">Multi-threading</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="rzakzfinder.htm">System value finder</a></div>
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</div>
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</div>
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</body>
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</html>
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