1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [ |
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4 | <!ENTITY % general-entities SYSTEM "../general.ent"> |
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5 | %general-entities; |
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6 | ]> |
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7 | |
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8 | <sect1 id="ch-final-preps-aboutsbus"> |
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9 | <?dbhtml filename="aboutsbus.html"?> |
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10 | |
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11 | <title>About SBUs</title> |
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12 | |
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13 | <para>TO BE REWRITTEN</para> |
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14 | |
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15 | <!-- |
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16 | <para>Many people would like to know beforehand approximately how long |
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17 | it takes to compile and install each package. Because Linux From |
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18 | Scratch can be built on many different systems, it is impossible to |
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19 | provide accurate time estimates. The biggest package (Glibc) will |
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20 | take approximately 20 minutes on the fastest systems, but could take |
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21 | up to three days on slower systems! Instead of providing actual times, |
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22 | the Static Build Unit (SBU) measure will be |
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23 | used instead.</para> |
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24 | |
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25 | <para>The SBU measure works as follows. The first package to be compiled |
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26 | from this book is the statically-linked Binutils in <xref |
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27 | linkend="chapter-temporary-tools"/>. The time it takes to compile |
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28 | this package is what will be referred to as the Static Build Unit |
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29 | or SBU. All other compile times will be expressed relative to this |
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30 | time.</para> |
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31 | |
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32 | <para>For example, consider a package whose compilation time is 4.5 |
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33 | SBUs. This means that if a system took 10 minutes to compile and |
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34 | install the static Binutils, it will take |
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35 | <emphasis>approximately</emphasis> 45 minutes to build this example |
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36 | package. Fortunately, most build times are shorter than the one |
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37 | for Binutils.</para> |
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38 | |
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39 | <para>Please note that if the system compiler on the host is GCC-2.x based, the |
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40 | SBUs listed may be somewhat understated. This is because the SBU is |
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41 | based on the very first package, compiled with the old GCC, while the |
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42 | rest of the system is compiled with the newer GCC-&gcc-version; (which is |
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43 | known to be approximately 30 percent slower). SBUs are also not |
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44 | highly accurate for Symmetric Multi-Processor (SMP)-based machines.</para> |
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45 | |
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46 | <para>In general, SBUs are not entirely accurate because they depend on many |
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47 | factors, including the host system's version of GCC. Note that on Symmetric |
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48 | Multi-Processor (SMP)-based machines, SBUs are even less accurate. They are |
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49 | provided here to give an estimate of how long it might take to install a |
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50 | package, but the numbers can vary by as much as dozens of minutes in some |
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51 | cases.</para> |
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52 | |
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53 | <para>To view actual timings for a number of specific machines, we recommend |
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54 | <ulink url="&lfs-root;~bdubbs/"/>.</para> |
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55 | --> |
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56 | |
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57 | </sect1> |
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