| [411] | 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>vfs_readahead</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_readahead.8"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>vfs_readahead — pre-load the kernel buffer cache</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis"><p><code class="literal">vfs objects = readahead</code></p></div></div><div class="refsect1" lang="en"><a name="id2522914"></a><h2>DESCRIPTION</h2><p>This VFS module is part of the
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| [368] | 2 | <a class="citerefentry" href="samba.7.html"><span class="citerefentry"><span class="refentrytitle">samba</span>(7)</span></a> suite.</p><p>This <code class="literal">vfs_readahead</code> VFS module detects
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| 3 | read requests at multiples of a given offset (hex 0x80000 by
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| 4 | default) and then tells the kernel via either the readahead
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| 5 | system call (on Linux) or the posix_fadvise system call to
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| 6 | pre-fetch this data into the buffer cache.</p><p>This module is useful for Windows Vista clients reading
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| 7 | data using the Windows Explorer program, which asynchronously
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| 8 | does multiple file read requests at offset boundaries of 0x80000
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| 9 | bytes.</p><p>The offset multiple used is given by the readahead:offset
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| 10 | option, which defaults to 0x80000.</p><p>The size of the disk read operations performed
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| 11 | by <code class="literal">vfs_readahead</code> is determined by the
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| 12 | readahead:length option. By default this is set to the
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| 13 | same value as the readahead:offset option and if not
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| 14 | set explicitly will use the current value of
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| [411] | 15 | readahead:offset.</p><p>This module is stackable.</p></div><div class="refsect1" lang="en"><a name="id2483344"></a><h2>OPTIONS</h2><div class="variablelist"><p>The following suffixes may be applied to BYTES:</p><div class="itemizedlist"><ul type="disc"><li><p><code class="literal">K</code> - BYTES is a number of kilobytes</p></li><li><p><code class="literal">M</code> - BYTES is a number of megabytes</p></li><li><p><code class="literal">G</code> - BYTES is a number of gigabytes</p></li></ul></div><dl><dt><span class="term">readahead:offset = BYTES</span></dt><dd><p>The offset multiple that causes readahead to be
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| [368] | 16 | requested of the kernel buffer cache.</p></dd><dt><span class="term">readahead:length = BYTES</span></dt><dd><p>The number of bytes requested to be
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| 17 | read into the kernel buffer cache on each
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| [411] | 18 | readahead call.</p></dd></dl></div></div><div class="refsect1" lang="en"><a name="id2483542"></a><h2>EXAMPLES</h2><pre class="programlisting">
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| [368] | 19 | <em class="parameter"><code>[hypothetical]</code></em>
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| 20 | <a class="link" href="smb.conf.5.html#VFSOBJECTS" target="_top">vfs objects = readahead</a>
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| [411] | 21 | </pre></div><div class="refsect1" lang="en"><a name="id2483672"></a><h2>VERSION</h2><p>This man page is correct for version 3.0.25 of the Samba suite.
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| 22 | </p></div><div class="refsect1" lang="en"><a name="id2483683"></a><h2>AUTHOR</h2><p>The original Samba software and related utilities
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| [368] | 23 | were created by Andrew Tridgell. Samba is now developed
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| 24 | by the Samba Team as an Open Source project similar
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| 25 | to the way the Linux kernel is developed.</p></div></div></body></html>
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