Add docs for readahead vfs module.

Jeremy.
(This used to be commit 6842a35595e1250aa79b5436106bf18b31ab713f)

1 files changed, 113 insertions, 0 deletions

diff --git a/docs/manpages-3/vfs_readahead.8.xml b/docs/manpages-3/vfs_readahead.8.xml
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+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
+<refentry id="vfs_readahead.8">
+
+<refmeta>
+	<refentrytitle>vfs_readahead</refentrytitle>
+	<manvolnum>8</manvolnum>
+</refmeta>
+
+
+<refnamediv>
+	<refname>vfs_readahead</refname>
+	<refpurpose>pre-load the kernel buffer cache</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+	<cmdsynopsis>
+		<command>vfs objects = readahead</command>
+	</cmdsynopsis>
+</refsynopsisdiv>
+
+<refsect1>
+	<title>DESCRIPTION</title>
+
+	<para>This VFS module is part of the
+	<citerefentry><refentrytitle>samba</refentrytitle>
+	<manvolnum>7</manvolnum></citerefentry> suite.</para>
+
+	<para>This <command>vfs_readahead</command> VFS module detects
+	read requests at multiples of a given offset (hex 0x80000 by
+	default) and then tells the kernel via either the readahead
+	system call (on Linux) or the posix_fadvise system call to
+	pre-fetch this data into the buffer cache.</para>
+
+	<para>This module is useful for Windows Vista clients reading
+	data using the Windows Explorer program, which asynchronously
+	does multiple file read requests at offset boundaries of 0x80000
+	bytes.</para>
+
+	<para>The offset multiple used is given by the readahead:offset
+	option, which defaults to 0x80000.</para>
+
+	<para>The size of the disk read operations performed
+	by <command>vfs_readahead</command> is determined by the
+	readahead:length option. By default this is set to the
+	same value as the readahead:offset option and if not
+	set explicitly will use the current value of
+	readahead:offset.</para>
+
+	<para>This module is stackable.</para>
+</refsect1>
+
+<refsect1>
+	<title>OPTIONS</title>
+
+	<variablelist>
+
+		<varlistentry>
+		<term>readahead:offset = BYTES</term>
+		<listitem>
+		<para>The offset multiple that causes readahead to be
+		requested of the kernel buffer cache.</para>
+		</listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>readahead:length = BYTES</term>
+		<listitem>
+		<para>The number of bytes requested to be
+		read into the kernel buffer cache on each
+		readahead call.</para>
+		</listitem>
+		</varlistentry>
+
+		<para>The following suffixes may be applied to BYTES:</para>
+		<itemizedlist>
+		<listitem><para><command>K</command> - BYTES is a number of kilobytes</para></listitem>
+		<listitem><para><command>M</command> - BYTES is a number of megabytes</para></listitem>
+		<listitem><para><command>G</command> - BYTES is a number of gigabytes</para></listitem>
+		</itemizedlist>
+
+
+	</variablelist>
+</refsect1>
+
+<refsect1>
+	<title>EXAMPLES</title>
+
+<programlisting>
+	<smbconfsection name="[hypothetical]"/>
+	<smbconfoption name="vfs objects">readahead</smbconfoption>
+	<smbconfoption name="readahead:length">1M</smbconfoption>
+</programlisting>
+
+</refsect1>
+
+<refsect1>
+	<title>VERSION</title>
+	<para>This man page is correct for version 3.0.25 of the Samba suite.
+	</para>
+</refsect1>
+
+<refsect1>
+	<title>AUTHOR</title>
+
+	<para>The original Samba software and related utilities
+	were created by Andrew Tridgell. Samba is now developed
+	by the Samba Team as an Open Source project similar
+	to the way the Linux kernel is developed.</para>
+
+</refsect1>
+
+</refentry>