<h1 id="cgroup">Cgroup<a aria-hidden="true" class="anchor-heading icon-link" href="#cgroup"></a></h1>
<p>A control group (cgroup) is a Linux kernel feature that limits, accounts for, and <strong>isolates the resource usage</strong> (CPU, memory, disk I/O, network, and so on) of a collection of processes.</p>
<p>Cgroups provide the following features:</p>
<ul>
<li>Resource limits – You can configure a cgroup to limit how much of a particular resource (memory or CPU, for example) <strong>a process can use</strong>.</li>
<li>Prioritization – You can control how much of a resource (CPU, disk, or network) a process can use compared to processes in another cgroup when there is resource contention.</li>
<li>Accounting – Resource limits are monitored and reported at the cgroup level.</li>
<li>Control – You can change the status (frozen, stopped, or restarted) of all processes in a cgroup with a single command.</li>
</ul>
<h1 id="how-to-configure">how to configure<a aria-hidden="true" class="anchor-heading icon-link" href="#how-to-configure"></a></h1>
<p>The following command creates a v1 cgroup (you can tell by pathname format) called foo and sets the memory limit for it to 50,000,000 bytes (50 MB).</p>
<pre><code>root # mkdir -p /sys/fs/cgroup/memory/foo
root # echo 50000000 > /sys/fs/cgroup/memory/foo/memory.limit_in_bytes
</code></pre>
<p>I start test.sh in the background and its PID is reported as 2428. The script produces its output and then I assign the process to the cgroup by piping its PID into the cgroup file /sys/fs/cgroup/memory/foo/cgroup.procs.</p>
<pre><code>root # ./test.sh &#x26;
[1] 2428
root # cgroup testing tool
root # echo 2428 > /sys/fs/cgroup/memory/foo/cgroup.procs
</code></pre>