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 V1.71.0"></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="id291819"></a><h2>DESCRIPTION</h2><p>This VFS module is part of the 2 <a 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 3 read requests at multiples of a given offset (hex 0x80000 by 4 default) and then tells the kernel via either the readahead 5 system call (on Linux) or the posix_fadvise system call to 6 pre-fetch this data into the buffer cache.</p><p>This module is useful for Windows Vista clients reading 7 data using the Windows Explorer program, which asynchronously 8 does multiple file read requests at offset boundaries of 0x80000 9 bytes.</p><p>The offset multiple used is given by the readahead:offset 10 option, which defaults to 0x80000.</p><p>The size of the disk read operations performed 11 by <code class="literal">vfs_readahead</code> is determined by the 12 readahead:length option. By default this is set to the 13 same value as the readahead:offset option and if not 14 set explicitly will use the current value of 15 readahead:offset.</p><p>This module is stackable.</p></div><div class="refsect1" lang="en"><a name="id259558"></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 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 17 read into the kernel buffer cache on each 18 readahead call.</p></dd></dl></div></div><div class="refsect1" lang="en"><a name="id259379"></a><h2>EXAMPLES</h2><pre class="programlisting"> 19 <em class="parameter"><code>[hypothetical]</code></em> 20 <a class="indexterm" name="id259394"></a>vfs objects = readahead 21</pre></div><div class="refsect1" lang="en"><a name="id259404"></a><h2>VERSION</h2><p>This man page is correct for version 3.0.25 of the Samba suite. 22 </p></div><div class="refsect1" lang="en"><a name="id259414"></a><h2>AUTHOR</h2><p>The original Samba software and related utilities 23 were created by Andrew Tridgell. Samba is now developed 24 by the Samba Team as an Open Source project similar 25 to the way the Linux kernel is developed.</p></div></div></body></html> 26