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Added a note to address parallel make procedures
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@9099 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
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@ -40,6 +40,11 @@
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<listitem>
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<listitem>
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<para>2009-11-12</para>
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<para>2009-11-12</para>
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<itemizedlist>
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<itemizedlist>
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<listitem>
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<para>[bdubbs] Added a note to 'About SBUs' to address
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parallel make procedures and how SBU values will be
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affected.</para>
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</listitem>
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<listitem>
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<listitem>
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<para>[bdubbs] Minor changes to GRUB-1.9.1 instructions.</para>
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<para>[bdubbs] Minor changes to GRUB-1.9.1 instructions.</para>
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</listitem>
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</listitem>
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@ -32,14 +32,33 @@
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Fortunately, most build times are shorter than the one for Binutils.</para>
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Fortunately, most build times are shorter than the one for Binutils.</para>
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<para>In general, SBUs are not entirely accurate because they depend on many
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<para>In general, SBUs are not entirely accurate because they depend on many
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factors, including the host system's version of GCC. Note that on Symmetric
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factors, including the host system's version of GCC. They are provided here
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Multi-Processor (SMP)-based machines, SBUs are even less accurate. They are
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to give an estimate of how long it might take to install a package, but the
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provided here to give an estimate of how long it might take to install a
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numbers can vary by as much as dozens of minutes in some cases.</para>
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package, but the numbers can vary by as much as dozens of minutes in some
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cases.</para>
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<para>To view actual timings for a number of specific machines, we recommend
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<para>To view actual timings for a number of specific machines, we recommend
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The LinuxFromScratch SBU Home Page at <ulink url="&lfs-root;~sbu/"/>.</para>
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The LinuxFromScratch SBU Home Page at <ulink url="&lfs-root;~sbu/"/>.</para>
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<note><para>For many modern systems with multiple processors (or cores) the
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compilation time for a package can be reduced by performing a "parallel make"
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by either setting an environment variable or telling the
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<command>make</command> program how many processors are available. For
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instance, a Core2Duo can support two simultaneous processes with:</para>
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<screen><userinput>set MAKEFLAGS='-j 2'</userinput></screen>
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<para>or just building with:</para>
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<screen><userinput>make -j2</userinput></screen>
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<para>When multiple processors are used in this way, the SBU units in the
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book will vary even more than they normally would. Analyzing the output of
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the build process will also be more difficult because the lines of different
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processes will be interleaved. If you run into a problem with a build step,
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revert back to a single processor build to properly analyze the error
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messages.</para>
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</note>
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</sect1>
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</sect1>
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