https://wiki.openvz.org/api.php?action=feedcontributions&user=90.165.252.186&feedformat=atomOpenVZ Virtuozzo Containers Wiki - User contributions [en]2024-03-29T09:27:20ZUser contributionsMediaWiki 1.31.1https://wiki.openvz.org/index.php?title=I/O_priorities&diff=19487I/O priorities2016-04-24T14:02:03Z<p>90.165.252.186: Corrected a mispelling error, but still there is an important question unanswered, what is HZ?</p>
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<div>The I/O priorities feature is implemented in OpenVZ since kernel <tt>2.6.18-028stab021</tt>, <tt>vzctl 3.0.16</tt>. This feature allows to assign I/O priority to any [[container]]. Priority range is <tt>0-7</tt>. The more priority a container has, the more time for using block devices this container will obtain. This feature is based on CFQ I/O scheduler, so this scheduler should be used for block device in question. Default I/O priority is <tt>4</tt>.<br />
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== Examples ==<br />
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Set the lowest priority:<br />
vzctl set 101 --ioprio 0 --save<br />
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Set the highest priority:<br />
vzctl set 101 --ioprio 7 --save<br />
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== Details ==<br />
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The higher the value you use, the more I/O time your container will receive. <br />
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The mapping from priority to time is the following: if <tt>0</tt> prio corresponds to time slice <tt>t</tt>, then <tt>7</tt> prio corresponds to time slice <tt>2 * t</tt>. Default time slice value is <tt>HZ/2</tt>. The main criteria for fairness at the moment is that if you set I/O prio of CT 1 to <tt>p1</tt> and I/O prio of CT 2 to <tt>p2</tt>, and <tt>p1 > p2</tt> then CT 1 should do more I/O than CT 2. In simple form the priorities are relative with the higher priority getting more I/O time.<br />
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== See also ==<br />
* [[I/O limits]]<br />
* [[IO accounting]]<br />
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[[Category: Resource management]]<br />
[[Category: HOWTO]]</div>90.165.252.186