91 lines
6.7 KiB
HTML
91 lines
6.7 KiB
HTML
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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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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="How work gets processed" />
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<meta name="abstract" content="When the iSeries server is started, a subsystem monitor job begins running. The subsystem monitor job controls the jobs within subsystems. It also starts and ends work, as well as manages the resources for work in the subsystem." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004-2006" />
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<title>How work gets processed</title>
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</head>
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<body id="rzakshowwrkgetsproc"><a name="rzakshowwrkgetsproc"><!-- --></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">How work gets processed</h1>
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<div><p>When the iSeries™ server is started, a subsystem monitor job
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begins running. The subsystem monitor job controls the jobs within subsystems.
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It also starts and ends work, as well as manages the resources for work in
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the subsystem. </p>
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<p> Work (or jobs) enters a subsystem through work entries where it becomes
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active and eligible to run. Work can only be completed when the subsystem
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has allocated memory to run. Memory is allocated to the subsystem by a memory
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pool.</p>
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<div class="section"><h4 class="sectiontitle">How the subsystem description helps process work</h4><p>Like
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a job, a subsystem has a description, called a subsystem description. The
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subsystem description contains important information that tells how, where,
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how much work can be active in a subsystem at one time, and which resources
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it can use to perform the work.</p>
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<dl><dt class="dlterm">Routing entry</dt>
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<dd>A routing entry exists within the subsystem description and tells the
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subsystem what program to run for the job, what memory pool to run the job
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in, and which class object to use to run the job.</dd>
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<dt class="dlterm">Class Object</dt>
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<dd>The Class object defines the run priority, default wait time, time slice,
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and other attributes. The run priority is important because it determines
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when a job will get processor time in order to run. The run priority scale
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goes from 0 to 99, with 0 being the highest priority. (Only system jobs are
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given priority of 0 because they are the jobs that run the iSeries server.)</dd>
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</dl>
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<p>When a job enters the subsystem, the subsystem tries to
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match the routing data with the compare value in the routing entry. If the
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routing data and the compare value in a routing entry match, the routing entry
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is assigned to the job. If a match is not made in any routing entry, the job
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ends.</p>
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<p>Another factor that affects when a job runs in the subsystem is
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the number of jobs that are allowed to be active in the subsystem at one time
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(also known as maximum active jobs in the subsystem). When the maximum number
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of active jobs in a subsystem has been met, no more jobs can enter the subsystem
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until existing active jobs complete running. Memory has to be allocated to
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the subsystem for a job to run. Memory pool activity levels tell the iSeries server
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how many threads can be active within a memory pool. Remember, an active job
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contains at least one thread. When the memory pool activity level has been
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reached, the job has to wait for another thread to give up its use of the
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activity level. Thus, a job can be active in a subsystem and
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not be running.</p>
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<div class="note"><span class="notetitle">Note:</span> Do not confuse the subsystem maximum active jobs
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with the memory pool activity level.</div>
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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="rzakshowworkgetsdone.htm" title="Use this information to learn about what work is, what needs to be set up before work can begin, how work travels through the system, and what happens to work after it is done running.">How work gets done</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzakswhatswrk.htm" title="On the iSeries server, work is always being done, whether you initiate it or the system initiates it. Any action done on the iSeries server has some type of work being performed to complete it.">What work is</a></div>
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<div><a href="rzaksbfrwrkentsys.htm" title="All jobs, with the exception of system jobs, run within subsystems. For work to start in an active subsystem, memory pools and at least one source of work entry point need to be established. Job queues are an example of a source of work.">What happens before work enters the system</a></div>
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<div><a href="rzakshowwrkgetsinsys.htm" title="Work entries identify the sources where jobs enter a subsystem to become available to run. Each type of job on the iSeries has different types of work entries that it uses.">How work enters the system</a></div>
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<div><a href="rzakshowwrklvs.htm" title="The output queue works similarly to a job queue in that it schedules output to be printed. Both the printer output and the output queue carry attributes that are used to print the information.">How work leaves the system</a></div>
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</div>
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</div>
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</body>
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</html> |