Changeset 81fd230 for chapter04/aboutsbus.xml

Timestamp:

02/19/2005 10:16:42 PM (19 years ago)

Author:

Gerard Beekmans <gerard@…>

Branches:

10.0, 10.0-rc1, 10.1, 10.1-rc1, 11.0, 11.0-rc1, 11.0-rc2, 11.0-rc3, 11.1, 11.1-rc1, 11.2, 11.2-rc1, 11.3, 11.3-rc1, 12.0, 12.0-rc1, 12.1, 12.1-rc1, 6.1, 6.1.1, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.5-systemd, 7.6, 7.6-systemd, 7.7, 7.7-systemd, 7.8, 7.8-systemd, 7.9, 7.9-systemd, 8.0, 8.1, 8.2, 8.3, 8.4, 9.0, 9.1, arm, bdubbs/gcc13, ml-11.0, multilib, renodr/libudev-from-systemd, s6-init, trunk, xry111/arm64, xry111/arm64-12.0, xry111/clfs-ng, xry111/lfs-next, xry111/loongarch, xry111/loongarch-12.0, xry111/loongarch-12.1, xry111/mips64el, xry111/pip3, xry111/rust-wip-20221008, xry111/update-glibc

Children:

3d31fc4

Parents:

2f9131f

Message:

Trunk is now identical to Testing

git-svn-id: ​http://svn.linuxfromscratch.org/LFS/trunk/BOOK@4648 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

File:

• chapter04/aboutsbus.xml (modified) (1 diff)

chapter04/aboutsbus.xml

@@ -8 +8 @@
 <?dbhtml filename="aboutsbus.html"?>
 
-<para>See testing</para>
+<para>Many people would like to know beforehand approximately how long
+it takes to compile and install each package. Because Linux From
+Scratch can be built on many different systems, it is impossible to
+provide accurate time estimates.  The biggest package (Glibc) will
+take approximately 20 minutes on the fastest systems, but could take
+up to three days on slower systems! Instead of providing actual times,
+the Static Build Unit (SBU) measure will be
+used instead.</para>
+
+<para>The SBU measure works as follows. The first package to be compiled
+from this book is the statically-linked Binutils in <xref
+linkend="chapter-temporary-tools"/>.  The time it takes to compile
+this package is what will be referred to as the Static Build Unit
+or SBU. All other compile times will be expressed relative to this
+time.</para>
+
+<para>For example, consider a package whose compilation time is 4.5
+SBUs. This means that if a system took 10 minutes to compile and
+install the static Binutils, it will take
+<emphasis>approximately</emphasis> 45 minutes to build this example
+package. Fortunately, most build times are shorter than the one
+for Binutils.</para>
+
+<para>Please note that if the system compiler on the host is GCC-2.x based, the
+SBUs listed may be 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-&gcc-version; (which is
+known to be approximately 30 percent slower). SBUs are also not
+highly accurate for Symmetric Multi-Processor (SMP)-based machines.</para>
+
+<para>To view actual timings for a number of specific machines, we recommend
+<ulink url="&lfs-root;~bdubbs/"/>.</para>
+
+<para>In general, SBUs are not very accurate because they depend on many
+factors, not just the GCC version. They are provided
+here to give an estimate of how long it might take to
+install a package, but the numbers can vary by as much as dozens of
+minutes in some cases.</para>
 
 </sect1>
+