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+<?xml version="1.0" encoding="ISO-8859-1"?>
+<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
+  <!ENTITY % general-entities SYSTEM "../general.ent">
+  %general-entities;
+]>
+<sect1 id="prepare-aboutsbus">
+<title>About SBUs</title>
+<?dbhtml filename="aboutsbus.html"?>
+
+<para>Most people would like to know beforehand approximately how long it
+takes to compile and install each package. But "Linux from Scratch" is built
+on so many different systems, it is not possible to give actual times that are
+anywhere near accurate: the biggest package (Glibc) won't take more than
+twenty minutes on the fastest systems, but will take something like three days
+on the slowest -- no kidding. So instead of giving actual times, we've come up
+with the idea of using the <emphasis>Static Binutils Unit</emphasis>
+(abbreviated to <emphasis>SBU</emphasis>).</para>
+
+<para>It works like this: the first package you compile in this book is the
+statically linked Binutils in <xref linkend="chapter-temporary-tools"/>, and the time it
+takes to compile this package is what we call the <quote>Static Binutils
+Unit</quote> or <quote>SBU</quote>. All other compile times will be expressed
+relative to this time.</para>
+
+<para>For example, consider a particular package whose compilation time is 4.5
+SBUs. This means that if on your system it took 10 minutes to compile and
+install the static Binutils, then you know it will take
+<emphasis>approximately</emphasis> 45 minutes to build this package.
+Fortunately, most build times are much shorter than the one of Binutils.</para>
+
+<para>Note that if the system compiler on your host is GCC-2 based, the SBUs
+listed may end up being somewhat understated. This is because the SBU is based
+on the very first package, compiled with the old GCC, while the rest of the
+system is compiled with the newer GCC-3.3.2 which is known to be
+approximately 30% slower.</para>
+
+<para>Also note that SBUs don't work well for SMP-based machines. But if you're
+so lucky as to have multiple processors, chances are that your system is so fast
+that you won't mind.</para>
+
+<para>If you wish to see actual timings for specific machines, have a look at
+<ulink url="&lfs-root;~bdubbs/"/>.</para>
+
+</sect1>