| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>vfs_preopen</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en"><a name="vfs_preopen.8"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>vfs_preopen — Hide read latencies for applications reading numbered files</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis"><p><code class="literal">vfs objects = preopen</code></p></div></div><div class="refsect1" lang="en"><a name="id2522916"></a><h2>DESCRIPTION</h2><p>This VFS module is part of the
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| 2 | <a class="citerefentry" href="samba.7.html"><span class="citerefentry"><span class="refentrytitle">samba</span>(7)</span></a> suite.</p><p>This module assists applications that want to read numbered
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| 3 | files in sequence with very strict latency requirements. One area
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| 4 | where this happens in video streaming applications that want to read
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| 5 | one file per frame.</p><p>When you use this module, a number of helper processes is
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| 6 | started that speculatively open files and read a number of bytes to
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| 7 | prime the file system cache, so that later on when the real
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| 8 | application's request comes along, no disk access is necessary.</p><p>This module is stackable.</p></div><div class="refsect1" lang="en"><a name="id2522951"></a><h2>OPTIONS</h2><div class="variablelist"><dl><dt><span class="term">preopen:names = /pattern/</span></dt><dd><p>
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| 9 | preopen:names specifies the file name pattern which should
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| 10 | trigger the preopen helpers to do their work. We assume that
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| 11 | the files are numbered incrementally. So if your file names
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| 12 | are numbered FRAME00000.frm FRAME00001.frm and so on you would
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| 13 | list them as <code class="literal">preopen:names=/FRAME*.frm/</code>
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| 14 | </p></dd><dt><span class="term">preopen:num_bytes = BYTES</span></dt><dd><p>
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| 15 | Specifies the number of bytes the helpers should speculatively
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| 16 | read, defaults to 1.
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| 17 | </p></dd><dt><span class="term">preopen:helpers = NUM-PROCS</span></dt><dd><p>
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| 18 | Number of forked helper processes, defaults to 1.
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| 19 | </p></dd><dt><span class="term">preopen:queuelen = NUM-FILES</span></dt><dd><p>
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| 20 | Number of files that should be speculatively opened. Defaults
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| 21 | to the 10 subsequent files.
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| 22 | </p></dd></dl></div></div><div class="refsect1" lang="en"><a name="id2483396"></a><h2>VERSION</h2><p>This man page is correct for version 3.3 of the Samba suite.
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| 23 | </p></div><div class="refsect1" lang="en"><a name="id2483532"></a><h2>AUTHOR</h2><p>The original Samba software and related utilities
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| 24 | were created by Andrew Tridgell. Samba is now developed
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| 25 | by the Samba Team as an Open Source project similar
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| 26 | to the way the Linux kernel is developed.</p><p>The PREOPEN VFS module was created with contributions from
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| 27 | Volker Lendecke and the developers at IBM.
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| 28 | </p></div></div></body></html>
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