Added a note to address parallel make procedures

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@9099 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
This commit is contained in:
Bruce Dubbs 2009-11-13 02:09:23 +00:00
parent 6ea017a241
commit 86861ee625
2 changed files with 29 additions and 5 deletions

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<listitem> <listitem>
<para>2009-11-12</para> <para>2009-11-12</para>
<itemizedlist> <itemizedlist>
<listitem>
<para>[bdubbs] Added a note to 'About SBUs' to address
parallel make procedures and how SBU values will be
affected.</para>
</listitem>
<listitem> <listitem>
<para>[bdubbs] Minor changes to GRUB-1.9.1 instructions.</para> <para>[bdubbs] Minor changes to GRUB-1.9.1 instructions.</para>
</listitem> </listitem>

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Fortunately, most build times are shorter than the one for Binutils.</para> Fortunately, most build times are shorter than the one for Binutils.</para>
<para>In general, SBUs are not entirely accurate because they depend on many <para>In general, SBUs are not entirely accurate because they depend on many
factors, including the host system's version of GCC. Note that on Symmetric factors, including the host system's version of GCC. They are provided here
Multi-Processor (SMP)-based machines, SBUs are even less accurate. They are to give an estimate of how long it might take to install a package, but the
provided here to give an estimate of how long it might take to install a numbers can vary by as much as dozens of minutes in some cases.</para>
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 <para>To view actual timings for a number of specific machines, we recommend
The LinuxFromScratch SBU Home Page at <ulink url="&lfs-root;~sbu/"/>.</para> The LinuxFromScratch SBU Home Page at <ulink url="&lfs-root;~sbu/"/>.</para>
<note><para>For many modern systems with multiple processors (or cores) the
compilation time for a package can be reduced by performing a "parallel make"
by either setting an environment variable or telling the
<command>make</command> program how many processors are available. For
instance, a Core2Duo can support two simultaneous processes with:</para>
<screen><userinput>set MAKEFLAGS='-j 2'</userinput></screen>
<para>or just building with:</para>
<screen><userinput>make -j2</userinput></screen>
<para>When multiple processors are used in this way, the SBU units in the
book will vary even more than they normally would. Analyzing the output of
the build process will also be more difficult because the lines of different
processes will be interleaved. If you run into a problem with a build step,
revert back to a single processor build to properly analyze the error
messages.</para>
</note>
</sect1> </sect1>