Add a vfs_preopen module to hide fs latencies

1 files changed, 115 insertions, 0 deletions

diff --git a/docs-xml/manpages-3/vfs_preopen.8.xml b/docs-xml/manpages-3/vfs_preopen.8.xml
new file mode 100644
index 0000000000..a84d4720bb
--- /dev/null
+++ b/docs-xml/manpages-3/vfs_preopen.8.xml
@@ -0,0 +1,115 @@
+<?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_preopen.8">
+
+<refmeta>
+	<refentrytitle>vfs_preopen</refentrytitle>
+	<manvolnum>8</manvolnum>
+	<refmiscinfo class="source">Samba</refmiscinfo>
+	<refmiscinfo class="manual">System Administration tools</refmiscinfo>
+	<refmiscinfo class="version">3.3</refmiscinfo>
+</refmeta>
+
+<refnamediv>
+	<refname>vfs_preopen</refname>
+	<refpurpose>Hide read latencies for applications reading numbered files</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+	<cmdsynopsis>
+		<command>vfs objects = preopen</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 module assists applications that want to read numbered
+	files in sequence with very strict latency requirements. One area
+	where this happens in video streaming applications that want to read
+	one file per frame.</para>
+
+	<para>When you use this module, a number of helper processes is
+	started that speculatively open files and read a number of bytes to
+	prime the file system cache, so that later on when the real
+	application's request comes along, no disk access is necessary.</para>
+
+	<para>This module is stackable.</para>
+
+</refsect1>
+
+
+<refsect1>
+	<title>OPTIONS</title>
+
+	<variablelist>
+
+		<varlistentry>
+		<term>preopen:names = /pattern/</term>
+		<listitem>
+		<para>
+		preopen:names specifies the file name pattern which should
+		trigger the preopen helpers to do their work. We assume that
+		the files are numbered incrementally. So if your file names
+		are numbered FRAME00000.frm FRAME00001.frm and so on you would
+		list them as <command>preopen:names=/FRAME*.frm/</command>
+		</para>
+		</listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>preopen:num_bytes = BYTES</term>
+		<listitem>
+		<para>
+		Specifies the number of bytes the helpers should speculatively
+		read, defaults to 1.
+		</para>
+		</listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>preopen:helpers = NUM-PROCS</term>
+		<listitem>
+		<para>
+		Number of forked helper processes, defaults to 1.
+		</para>
+		</listitem>
+		</varlistentry>
+
+		<varlistentry>
+		<term>preopen:queuelen = NUM-FILES</term>
+		<listitem>
+		<para>
+		Number of files that should be speculatively opened. Defaults
+		to the 10 subsequent files.
+		</para>
+		</listitem>
+		</varlistentry>
+
+	</variablelist>
+</refsect1>
+
+<refsect1>
+	<title>VERSION</title>
+	<para>This man page is correct for version 3.3 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>
+
+	<para>The PREOPEN VFS module was created with contributions from
+	Volker Lendecke and the developers at IBM.
+	</para>
+</refsect1>
+
+</refentry>