[0b74af3] | 1 | <sect1 id="ch02-aboutsbus">
|
---|
| 2 | <title>About SBUs</title>
|
---|
| 3 | <?dbhtml filename="aboutsbus.html" dir="chapter02"?>
|
---|
| 4 |
|
---|
[dc37bc5] | 5 | <para>Most people would like to know beforehand how long it approximately
|
---|
| 6 | takes to compile and install each package. But "Linux from Scratch" is built
|
---|
| 7 | on so many different systems, it is not possible to give actual times that are
|
---|
| 8 | anywhere near accurate: the biggest package (Glibc) won't take more than
|
---|
| 9 | twenty minutes on the fastest systems, but will take something like three days
|
---|
| 10 | on the slowest -- no kidding. So instead of giving actual times, we've come up
|
---|
| 11 | with the idea of using the <emphasis>Static Binutils Unit</emphasis>
|
---|
| 12 | (abbreviated to <emphasis>SBU</emphasis>).</para>
|
---|
[0b74af3] | 13 |
|
---|
[dc37bc5] | 14 | <para>It works like this: the first package you compile in this book is the
|
---|
| 15 | statically linked Binutils in Chapter 5, and the time it takes to compile this
|
---|
| 16 | package is what we call the "Static Binutils Unit" or "SBU". All other compile
|
---|
| 17 | times will be expressed relative to this time.</para>
|
---|
[0b74af3] | 18 |
|
---|
[0dc87e0] | 19 | <para>For example, the time it takes to build the static version of GCC is
|
---|
| 20 | &gcc-time-tools-pass1;s. This means that if on your system it took 10 minutes
|
---|
| 21 | to compile and install the static Binutils, then you know it will take
|
---|
| 22 | approximately 45 minutes to build the static GCC. Fortunately, most build times
|
---|
| 23 | are much shorter than the one of Binutils.</para>
|
---|
[0b74af3] | 24 |
|
---|
[0dc87e0] | 25 | <para>Note that if the system compiler on your host is GCC-2 based, the SBUs
|
---|
[e98b158] | 26 | listed may end up being somewhat understated. This is because the SBU is based
|
---|
| 27 | on the very first package, compiled with the old GCC, while the rest of the
|
---|
[0dc87e0] | 28 | system is compiled with the newer GCC-&gcc-version; which is known to be
|
---|
| 29 | approximately 30% slower.</para>
|
---|
| 30 |
|
---|
| 31 | <para>Also note that SBUs don't work well for SMP-based machines. But if you're
|
---|
| 32 | so lucky as to have multiple processors, chances are that your system is so fast
|
---|
| 33 | that you won't mind.</para>
|
---|
[0b74af3] | 34 |
|
---|
[fae442d5] | 35 | <para>If you wish to see actual timings for specific machines, have a look at
|
---|
| 36 | <ulink url="http://www.linuxfromscratch.org/~bdubbs/"/>.</para>
|
---|
| 37 |
|
---|
[0b74af3] | 38 | </sect1>
|
---|
| 39 |
|
---|