Add more detail to the About SBUs page.

chapter04/aboutsbus.xml

@@ -26,9 +26,9 @@
   unit of time.</para>
 
   <para>For example, consider a package whose compilation time is 4.5
-  SBUs. This means that if your system took 10 minutes to compile and
+  SBUs. This means that if your system took 4 minutes to compile and
   install the first pass of binutils, it will take
-  <emphasis>approximately</emphasis> 45 minutes to build the example package.
+  <emphasis>approximately</emphasis> 18 minutes to build the example package.
   Fortunately, most build times are shorter than one SBU.</para>
 
   <para>SBUs are not entirely accurate because they depend on many
@@ -36,17 +36,26 @@
   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>Before measuring the build time of any package (no matter Binutils
+  <para>On some newer systems, the motherboard is capable of contolling 
-  pass 1 or a package of which the SBU is being measured), make sure a
+  the system clock speed. This can be controlled with a command such as
-  system power profile suitable to make the system running with the
+  <command>powerprofilesctl</command>. This is not available in LFS, but 
-  maximum performance (and the maximum power consumption) is selected.  Or
+  may be available on the host system. After LFS is complete, it can be 
-  the measured SBU value may be severly inaccurate because the system may be
+  added to a system with the procedures at the
-  operated differently building Binutils pass 1 and the other package.
+  <ulink url='&blfs-book;sysutils/power-profiles-daemon.html'>
+  BLFS power-profiles-daemon</ulink> page.
+
+  Before measuring the build time of any package it is advisable to use a
+  system power profile set for maximum performance (and maximum power 
+  consumption). 
+
+  Otherwise the measured SBU value may be inaccurate because the 
+  system may react differently when building <xref linkend='ch-tools-binutils-pass1'/>
+  or other packages.
+
   Be aware that a significant inaccuracy can still show up even if the same
-  profile (except one maximizing the performance) is used for both packages:
+  profile is used for both packages because the system may respond slower if
-  the system may respond slower for <quote>saving the power</quote> building
+  the system is idle when starting the build procedure. Setting the power
-  Binutils pass 1, because the system load seems only about 25% of the load
+  profile to "performance" will minimize this problem.</para>
-  building the other package (with <parameter>-j4</parameter>).</para>
 
   <para>On most distros the power profile can be managed with either
   <command>power-profiles-daemon</command> or <command>tuned</command>.
@@ -70,7 +79,9 @@
     interleaved.  If you run into a problem with a build step, revert to a
     single processor build to properly analyze the error messages.</para>
 
-    <para>The times presented here are based upon using four cores (-j4). The
+    <para>The times presented here for all packages 
+    (except <xref linkend='ch-tools-binutils-pass1'/> which is based on one core)
+    are based upon using four cores (-j4). The
     times in Chapter 8 also include the time to run the regression tests for
     the package unless specified otherwise.</para>
   </note>

chapter05/binutils-pass1.xml

@@ -5,7 +5,7 @@
   %general-entities;
 ]>
 
-<sect1 id="ch-tools-binutils-pass1" role="wrap">
+<sect1 id="ch-tools-binutils-pass1" role="wrap" xreflabel="binutils-pass1">
   <?dbhtml filename="binutils-pass1.html"?>
 
   <sect1info condition="script">