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Diffstat (limited to 'chapter04')
| -rw-r--r-- | chapter04/aboutsbus.xml | 35 |
1 files changed, 13 insertions, 22 deletions
diff --git a/chapter04/aboutsbus.xml b/chapter04/aboutsbus.xml index 34e1a1ef4..4385998d1 100644 --- a/chapter04/aboutsbus.xml +++ b/chapter04/aboutsbus.xml @@ -13,38 +13,29 @@ 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 +the Standard 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> +from this book is Binutils in <xref linkend="chapter-temporary-tools"/>. The +time it takes to compile this package is what will be referred to as the +Standard 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> +install the first pass of 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>In general, SBUs are not entirely accurate because they depend on many +factors, not just the GCC version. Note that on Symmetric Multi-Processor +(SMP)-based machines, SBUs are even less accurate. 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> <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> |