Changeset eae92372

Timestamp:

08/26/2024 10:59:31 PM (3 weeks ago)

Author:

Bruce Dubbs <bdubbs@…>

Branches:

12.2, multilib, trunk, xry111/arm64, xry111/clfs-ng, xry111/loongarch, xry111/loongarch-12.2, xry111/mips64el, xry111/multilib

Children:

68c63ae

Parents:

04befc5e

Message:

Add more detail to the About SBUs page.

Files:

• chapter04/aboutsbus.xml (modified) (3 diffs)
• chapter05/binutils-pass1.xml (modified) (1 diff)

chapter04/aboutsbus.xml

@@ -27 +27 @@
 
   <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>
 
@@ -37 +37 @@
   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
-  pass 1 or a package of which the SBU is being measured), make sure a
-  system power profile suitable to make the system running with the
-  maximum performance (and the maximum power consumption) is selected.  Or
-  the measured SBU value may be severly inaccurate because the system may be
-  operated differently building Binutils pass 1 and the other package.
+  <para>On some newer systems, the motherboard is capable of contolling 
+  the system clock speed. This can be controlled with a command such as
+  <command>powerprofilesctl</command>. This is not available in LFS, but 
+  may be available on the host system. After LFS is complete, it can be 
+  added to a system with the procedures at the
+  <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:
-  the system may respond slower for <quote>saving the power</quote> building
-  Binutils pass 1, because the system load seems only about 25% of the load
-  building the other package (with <parameter>-j4</parameter>).</para>
+  profile is used for both packages because the system may respond slower if
+  the system is idle when starting the build procedure. Setting the power
+  profile to "performance" will minimize this problem.</para>
 
   <para>On most distros the power profile can be managed with either
@@ -71 +80 @@
     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>

chapter05/binutils-pass1.xml

@@ -6 +6 @@
 ]>
 
-<sect1 id="ch-tools-binutils-pass1" role="wrap">
+<sect1 id="ch-tools-binutils-pass1" role="wrap" xreflabel="binutils-pass1">
   <?dbhtml filename="binutils-pass1.html"?>