CentOS7 禁用Transparent Huge Pages的实现方法
<p><strong>CentOS7 禁用Transparent Huge Pages</strong></p>
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自CentOS6版本开始引入了Transparent Huge Pages(THP)，从CentOS7版本开始，该特性默认就会启用。尽管THP的本意是为提升内存的性能，不过某些数据库厂商还是建议直接关闭THP(比如说ORACLE、MariaDB、MongoDB等)，否则可能会导致性能出现下降。</p>
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首先检查THP的启用状态：</p>
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<code class="bash plain"></code><code class="bash comments"># cat /sys/kernel/mm/transparent_hugepage/defrag</code>
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<code class="bash plain"> madvise never</code>
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<code class="bash plain"></code><code class="bash comments"># cat /sys/kernel/mm/transparent_hugepage/enabled</code>
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<code class="bash plain"> madvise never</code>
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这个状态就说明都是启用的。</p>
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我们这个时候当然可以逐个修改上述两文件，来禁用THP，但要想一劳永逸的令其永久生效，还是参考下列的步骤。</p>
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编辑rc.local文件：</p>
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<span># vim /etc/rc.d/rc.local </span></p>
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增加下列内容：</p>
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<code class="bash keyword">if</code> <code class="bash functions">test</code> <code class="bash plain">-f </code><code class="bash plain">/sys/kernel/mm/transparent_hugepage/enabled</code><code class="bash plain">; </code><code class="bash keyword">then</code>
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<code class="bash functions">echo</code> <code class="bash plain">never > </code><code class="bash plain">/sys/kernel/mm/transparent_hugepage/enabled</code>
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<code class="bash keyword">fi</code>
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<code class="bash keyword">if</code> <code class="bash functions">test</code> <code class="bash plain">-f </code><code class="bash plain">/sys/kernel/mm/transparent_hugepage/defrag</code><code class="bash plain">; </code><code class="bash keyword">then</code>
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<code class="bash functions">echo</code> <code class="bash plain">never > </code><code class="bash plain">/sys/kernel/mm/transparent_hugepage/defrag</code>
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<code class="bash keyword">fi</code>
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保存退出，然后赋予rc.local文件执行权限：</p>
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<span><strong># chmod +x /etc/rc.d/rc.local</strong></span></p>
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最后重启系统，以后再检查THP应该就是被禁用了</p>
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<code class="bash plain"></code><code class="bash comments"># cat /sys/kernel/mm/transparent_hugepage/enabled</code>
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<code class="bash plain">always madvise </code>
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<code class="bash plain"></code><code class="bash comments"># cat /sys/kernel/mm/transparent_hugepage/defrag </code>
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<code class="bash plain">always madvise </code>
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感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！</p>
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