65 lines
5.1 KiB
HTML
65 lines
5.1 KiB
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="A job's life: the subsystem uses memory from the memory pool to run the job" />
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<meta name="abstract" content="Memory is a resource from the memory pool that the subsystem uses to run the job. The amount of memory in a memory pool, as well as how many other jobs are competing for memory, affect how efficiently a job runs." />
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<meta name="description" content="Memory is a resource from the memory pool that the subsystem uses to run the job. The amount of memory in a memory pool, as well as how many other jobs are competing for memory, affect how efficiently a job runs." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2004-2006" />
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<title>A job's life: the subsystem uses memory from the memory
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pool to run the job</title>
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<body id="rzaksjoblifemp"><a name="rzaksjoblifemp"><!-- --></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">A job's life: the subsystem uses memory from the memory
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pool to run the job</h1>
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<div><p><dfn class="term">Memory</dfn> is a resource from the memory pool that the
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subsystem uses to run the job. The amount of memory in a memory pool, as well
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as how many other jobs are competing for memory, affect how efficiently a
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job runs.</p>
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<p><dfn class="term">Memory pools</dfn> provide jobs with memory in which to run. Many
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factors affect how the job runs in the memory pool, such as the size of the
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memory pool, the activity level in the memory pool, and paging and faulting.
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The activity level in memory pools directly relates to the number of threads
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that are allowed to run in the memory pool at one time. Remember, every job
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has at least one active thread, but some can have multiple threads. Threads
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give a job the ability to do more than one thing at a time. For example, one
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thread can go out and do calculations while another thread waits for more
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data to process. </p>
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<p> <dfn class="term">Paging</dfn> is the movement of data in and out of memory, both
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synchronously and asynchronously. Pages can be written out to storage or removed
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from memory without being written if they have not been changed. Faulting
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causes paging to occur on the server. Faulting occurs when a referenced page,
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or piece of data, is not in memory. This causes programs to stop because they
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must wait for the data to be paged in. </p>
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<p> Subsystems use different memory pools to support different types of jobs
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that run within them. </p>
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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="rzaksjoblife.htm" title="To understand the basics of iSeries work management, follow a simple batch job as it moves through the system.">A job's life</a></div>
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<div class="previouslink"><strong>Previous topic:</strong> <a href="rzaksjoblifesbs.htm" title="Subsystems are operating environments where the system manages the resources that jobs use and controls the jobs that run within them. After jobs are running in the subsystem, the subsystem job carries out user requests on a job such as holding, releasing, and ending a job. When the job enters the subsystem it becomes active.">A job's life: the job enters the subsystem</a></div>
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<div class="nextlink"><strong>Next topic:</strong> <a href="rzaksjoblifeoutq.htm" title="A job's printer output (also called spooled files) is sent to an output queue where it waits to be sent to a printer or file. The output queue is similar to the job queue in that it controls how the output is made available to the printer. The output queue allows the user to control what files are printed first.">A job's life: the job finishes and moves to the output queue</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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