mirror of
https://git.linuxfromscratch.org/lfs.git
synced 2025-01-19 05:27:39 +00:00
dcff0464e8
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@3221 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
40 lines
2.0 KiB
XML
40 lines
2.0 KiB
XML
<sect1 id="ch-prepare-aboutsbus">
|
|
<title>About SBUs</title>
|
|
<?dbhtml filename="aboutsbus.html" dir="chapter02"?>
|
|
|
|
<para>Most people would like to know beforehand how long it approximately
|
|
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 "Static Binutils Unit" or
|
|
"SBU". All other compile times will be expressed relative to this time.</para>
|
|
|
|
<para>For example, the time it takes to build the static version of GCC is
|
|
&gcc-time-tools-pass1;s. This means that if on your system it took 10 minutes
|
|
to compile and install the static Binutils, then you know it will take
|
|
approximately 45 minutes to build the static GCC. 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-&gcc-version; 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>
|
|
|