Changes between Initial Version and Version 1 of laguna/faq


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Timestamp:
10/24/2017 04:37:41 AM (5 years ago)
Author:
trac
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  • laguna/faq

    v1 v1  
     1{{{#!html
     2          <div id="wikipage" class="trac-content"><p>
     3</p><div class="wiki-toc">
     4<ol>
     5  <li>
     6    <a href="#LagunaFAQFrequentlyAskedQuestions"><b style="color:#000;background:#ffcc99">Laguna FAQ (Frequently Asked Questions</b>)</a>
     7    <ol>
     8      <li>
     9        <a href="#BogoMIPsvaluesappearlowerthenexpected">BogoMIPs values appear lower then expected</a>
     10      </li>
     11    </ol>
     12  </li>
     13</ol>
     14</div><p>
     15</p>
     16<h1 id="LagunaFAQFrequentlyAskedQuestions"><b style="color:#000;background:#ffcc99">Laguna FAQ (Frequently Asked Questions</b>)</h1>
     17<p>
     18<span class="wikianchor" id="bogomips"></span>
     19</p>
     20<h2 id="BogoMIPsvaluesappearlowerthenexpected">BogoMIPs values appear lower then expected</h2>
     21<p>
     22The reported bogoMIPS value is indeed bogus in the case of the ARM11 mpcore and other more modern ARM processors. The processor has a hardware function that helps to make "tight loops" more efficient by implementing branch folding. When the software attempts to discover its bogomips it executes a function called <span class="underline">delay with a number of instructions it wants to delay.  The </span>delay function is a "tight loop" and the branch instruction gets "folded" away causing the number of cycles to be far fewer than expected, yielding an incorrect value for bogomips.
     23</p>
     24<p>
     25For the Cavium cns3xxx processors, expect the following bogomips values:
     26</p>
     27<ul><li>dual-core 600Mhz cns3420 (GW2388): 239 bogomips each
     28</li><li>single-core 300MHz cns3410 (GW2380): 119 bogomips
     29</li></ul><p>
     30References:
     31</p>
     32<ul><li><a class="ext-link" href="http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0360f/ch06s02s04.html"><span class="icon">​</span>http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0360f/ch06s02s04.html</a>
     33</li><li><a class="ext-link" href="http://lists.infradead.org/pipermail/linux-arm-kernel/2010-January/008676.html"><span class="icon">​</span>http://lists.infradead.org/pipermail/linux-arm-kernel/2010-January/008676.html</a>
     34</li><li><a class="ext-link" href="http://lists.infradead.org/pipermail/linux-arm-kernel/2010-January/008912.html"><span class="icon">​</span>http://lists.infradead.org/pipermail/linux-arm-kernel/2010-January/008912.html</a>
     35</li></ul
     36}}}