<?xml version='1.0'?> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> <refentry id="iocost.conf" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>iocost.conf</title> <productname>systemd</productname> </refentryinfo> <refmeta> <refentrytitle>iocost.conf</refentrytitle> <manvolnum>5</manvolnum> </refmeta> <refnamediv> <refname>iocost.conf</refname> <refpurpose>Configuration files for the iocost solution manager</refpurpose> </refnamediv> <refsynopsisdiv> <para> <filename>/etc/systemd/iocost.conf</filename> <filename>/etc/systemd/iocost.conf.d/*.conf</filename> </para> </refsynopsisdiv> <refsect1> <title>Description</title> <para>This file configures the behavior of <literal>iocost</literal>, a tool mostly used by <citerefentry><refentrytitle>systemd-udevd</refentrytitle><manvolnum>8</manvolnum></citerefentry> rules to automatically apply I/O cost solutions to <filename>/sys/fs/cgroup/io.cost.*</filename>.</para> <para>The qos and model values are calculated based on benchmarks collected on the <ulink url="https://github.com/iocost-benchmark/iocost-benchmarks">iocost-benchmark</ulink> project and turned into a set of solutions that go from most to least isolated. Isolation allows the system to remain responsive in face of high I/O load. Which solutions are available for a device can be queried from the udev metadata attached to it. By default the naive solution is used, which provides the most bandwidth.</para> </refsect1> <xi:include href="standard-conf.xml" xpointer="main-conf" /> <refsect1> <title>Options</title> <para>All options are configured in the [IOCost] section:</para> <variablelist class='config-directives'> <varlistentry> <term><varname>TargetSolution=</varname></term> <listitem><para>Chooses which I/O cost solution (identified by named string) should be used for the devices in this system. The known solutions can be queried from the udev metadata attached to the devices. If a device does not have the specified solution, the first one listed in <varname>IOCOST_SOLUTIONS</varname> is used instead.</para> <para>E.g. <literal>TargetSolution=isolated-bandwidth</literal>.</para> <xi:include href="version-info.xml" xpointer="v254"/></listitem> </varlistentry> </variablelist> </refsect1> <refsect1> <title>See Also</title> <para><simplelist type="inline"> <member><citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry></member> <member><ulink url="https://github.com/iocost-benchmark/iocost-benchmarks">The iocost-benchmarks github project</ulink></member> <member><ulink url="https://github.com/facebookexperimental/resctl-demo/tree/main/resctl-bench/doc">The resctl-bench documentation details how the values are obtained</ulink></member> </simplelist></para> </refsect1> </refentry>