along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
-<refentry id="systemd-readahead-replay.service">
+<refentry id="systemd-readahead-replay.service" conditional='ENABLE_READAHEAD'
+ xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>systemd-readahead-replay.service</title>
<refname>systemd-readahead-done.service</refname>
<refname>systemd-readahead-done.timer</refname>
<refname>systemd-readahead</refname>
- <refpurpose>systemd Disk Read Ahead Logic</refpurpose>
+ <refpurpose>Disk read ahead logic</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd-readahead-collect.service</filename></para>
<para><filename>systemd-readahead-done.service</filename></para>
<para><filename>systemd-readahead-done.timer</filename></para>
- <para><filename>/usr/lib/systemd/systemd-readahead</filename></para>
+ <cmdsynopsis>
+ <command>/usr/lib/systemd/systemd-readahead/systemd-readahead</command>
+ <arg choice="opt" rep="repeat">OPTIONS</arg>
+ <arg choice="plain">COMMAND</arg>
+ <arg choice="opt">DIRECTORY | FILE</arg>
+ </cmdsynopsis>
</refsynopsisdiv>
<refsect1>
time. <filename>systemd-readahead-replay.service</filename>
is a service that replays this access data collected
at the subsequent boot. Since disks tend to be
- magnitudes slower than RAM this is intended to improve
+ magnitudes slower than RAM, this is intended to improve
boot speeds by pre-loading early at boot all data on
disk that is known to be read for the complete boot
process.</para>
<para><filename>systemd-readahead-done.service</filename>
is executed a short while after boot completed and signals
<filename>systemd-readahead-collect.service</filename>
- to end data collection. On this signal this service
+ to end data collection. On this signal, this service
will then sort the collected disk accesses and store
- information about them disk in
+ information about them in
<filename>/.readahead</filename>.</para>
<para>Normally, both
and
<filename>systemd-readahead-replay.service</filename>
are activated at boot so that access patterns from the
- preceeding boot are replayed and new data collected
+ preceding boot are replayed and new data collected
for the subsequent boot. However, on read-only media
- where the collected data cannot be stored it might
+ where the collected data cannot be stored, it might
be a good idea to disable
<filename>systemd-readahead-collect.service</filename>.</para>
<para>On rotating media, when replaying disk accesses
- at early boot
+ at early boot,
<filename>systemd-readahead-replay.service</filename>
will order read requests by their location on disk. On
non-rotating media, they will be ordered by their
original access timestamp. If the file system supports
- it
+ it,
<filename>systemd-readahead-collect.service</filename>
will also defragment and rearrange files on disk to
optimize subsequent boot times.</para>
</refsect1>
+ <refsect1>
+ <title>Options</title>
+
+ <para><filename>systemd-readahead</filename> understands
+ the following options:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>--files-max=</option></term>
+
+ <listitem><para>Maximum number of
+ files to read ahead. Only valid
+ for thes <command>collect</command>
+ command.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--file-size-max=</option></term>
+
+ <listitem><para>Maximum size of files
+ in bytes to read ahead. Only valid
+ for the <command>collect</command>
+ and <command>replay</command>
+ commands.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>--timeout=</option></term>
+
+ <listitem><para>Maximum time in microseconds
+ to spend collecting data. Only valid
+ for the <command>collect</command>
+ command.</para></listitem>
+ </varlistentry>
+
+ <xi:include href="standard-options.xml" xpointer="help" />
+ <xi:include href="standard-options.xml" xpointer="version" />
+ </variablelist>
+
+ </refsect1>
+
+ <refsect1>
+ <title>Commands</title>
+
+ <para>The following commands are understood by
+ <filename>systemd-readahead</filename>:</para> <variablelist>
+ <varlistentry>
+ <term><command>collect
+ [<replaceable>DIRECTORY</replaceable>]</command></term>
+ <listitem>
+ <para>Collect read-ahead data on
+ early boot. When terminating, it will
+ write out a pack file to the indicated
+ directory containing the read-ahead
+ data. </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><command>replay
+ [<replaceable>DIRECTORY</replaceable>]</command></term>
+ <listitem>
+ <para>Perform read-ahead on the
+ specified directory tree.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><command>analyze
+ [<replaceable>FILE</replaceable>]</command></term>
+ <listitem>
+ <para>Dumps the content of the
+ read-ahead pack file to the
+ terminal. For each file, the
+ output lists approximately how
+ much will be read ahead by
+ the <command>replay</command>
+ command.</para>
+ </listitem>
+ </varlistentry>
+
+ </variablelist>
+ </refsect1>
+
<refsect1>
<title>See Also</title>
<para>
~ianmdlvl / elogind.git / blobdiff