socket: Add support for TCP defer accept

[elogind.git] / man / systemd.socket.xml

diff --git a/man/systemd.socket.xml b/man/systemd.socket.xml
index d645de45e10ae074a1c64412c9c29450d045edd1..4483905832efe5feafe756515cd3253b90f39859 100644 (file)
--- a/man/systemd.socket.xml
+++ b/man/systemd.socket.xml
@@ -188,7 +188,7 @@
                                 replaced with a
                                 <constant>NUL</constant> character
                                 before binding. For details, see
                                 replaced with a
                                 <constant>NUL</constant> character
                                 before binding. For details, see

-                                <citerefentry><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+                                <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>

 
                                 <para>If the address string is a
                                 single number, it is read as port
 
                                 <para>If the address string is a
                                 single number, it is read as port


@@ -372,16 +372,21 @@
                         </varlistentry>
 
                         <varlistentry>
                         </varlistentry>
 
                         <varlistentry>

-                                <term><varname>DirectoryMode=</varname></term>
-                                <listitem><para>If listening on a file
-                                system socket or FIFO, the parent
-                                directories are automatically created
-                                if needed. This option specifies the
-                                file system access mode used when
-                                creating these directories. Takes an
-                                access mode in octal
-                                notation. Defaults to
-                                0755.</para></listitem>
+                                <term><varname>SocketUser=</varname></term>
+                                <term><varname>SocketGroup=</varname></term>
+
+                                <listitem><para>Takes a UNIX
+                                user/group name. When specified,
+                                all AF_UNIX sockets and FIFO nodes in
+                                the file system are owned by the
+                                specified user and group. If unset
+                                (the default), the nodes are owned by
+                                the root user/group (if run in system
+                                context) or the invoking user/group
+                                (if run in user context). If only a
+                                user is specified but no group, then
+                                the group is derived from the user's
+                                default group.</para></listitem>

                         </varlistentry>
 
                         <varlistentry>
                         </varlistentry>
 
                         <varlistentry>


@@ -395,6 +400,19 @@
                                 0666.</para></listitem>
                         </varlistentry>
 
                                 0666.</para></listitem>
                         </varlistentry>
 

+                        <varlistentry>
+                                <term><varname>DirectoryMode=</varname></term>
+                                <listitem><para>If listening on a file
+                                system socket or FIFO, the parent
+                                directories are automatically created
+                                if needed. This option specifies the
+                                file system access mode used when
+                                creating these directories. Takes an
+                                access mode in octal
+                                notation. Defaults to
+                                0755.</para></listitem>
+                        </varlistentry>
+

                         <varlistentry>
                                 <term><varname>Accept=</varname></term>
                                 <listitem><para>Takes a boolean
                         <varlistentry>
                                 <term><varname>Accept=</varname></term>
                                 <listitem><para>Takes a boolean


@@ -469,6 +487,53 @@
                                 <option>false</option>.</para></listitem>
                         </varlistentry>
 
                                 <option>false</option>.</para></listitem>
                         </varlistentry>
 

+                        <varlistentry>
+                                <term><varname>KeepAliveTime=</varname></term>
+                                <listitem><para>Takes time (in seconds) as argument . The connection needs to remain
+                                idle before TCP starts sending keepalive probes. This controls the TCP_KEEPIDLE
+                                socket option (see
+                                <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                and the <ulink
+                                url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+                                Keepalive HOWTO</ulink> for details.)
+                                Defaults value is 7200 seconds (2 hours).</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>KeepAliveInterval=</varname></term>
+                                <listitem><para>Takes time (in seconds) as argument between individual keepalive probes,
+                                if the socket option SO_KEEPALIVE has  been set on this socket seconds as argument.
+                                This controls the TCP_KEEPINTVL socket option (see
+                                <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                and the <ulink
+                                url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+                                Keepalive HOWTO</ulink> for details.)
+                                Defaults value is 75 seconds.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>KeepAliveProbes=</varname></term>
+                                <listitem><para>Takes interger as argument. It's the number of unacknowledged probes to
+                                send before considering the connection dead and notifying the application layer.
+                                This controls the TCP_KEEPCNT socket option (see
+                                <citerefentry><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                and the <ulink
+                                url="http://www.tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/">TCP
+                                Keepalive HOWTO</ulink> for details.)
+                                Defaults value is 9.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>NoDelay=</varname></term>
+                                <listitem><para>Takes a boolean
+                                argument. TCP Nagle's algorithm works by combining a number of
+                                small outgoing messages, and sending them all at once.
+                                This controls the TCP_NODELAY socket option (see
+                                <citerefentry><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                Defaults to
+                                <option>false</option>.</para></listitem>
+                        </varlistentry>
+

                         <varlistentry>
                                 <term><varname>Priority=</varname></term>
                                 <listitem><para>Takes an integer
                         <varlistentry>
                                 <term><varname>Priority=</varname></term>
                                 <listitem><para>Takes an integer


@@ -480,6 +545,47 @@
                                 for details.).</para></listitem>
                         </varlistentry>
 
                                 for details.).</para></listitem>
                         </varlistentry>
 

+                        <varlistentry>
+                                <term><varname>DeferAccept=</varname></term>
+
+                                <listitem><para>Takes time (in
+                                seconds) as argument. If set, the
+                                listening process will be awakened
+                                only when data arrives on the socket,
+                                and not immediately when connection is
+                                established. When this option is set,
+                                the
+                                <constant>TCP_DEFER_ACCEPT</constant>
+                                socket option will be used (see
+                                <citerefentry><refentrytitle>tcp</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
+                                and the kernel will ignore initial ACK
+                                packets without any data. The argument
+                                specifies the approximate amount of
+                                time the kernel should wait for
+                                incoming data before falling back to
+                                the normal behaviour of honouring
+                                empty ACK packets. This option is
+                                beneficial for protocols where the
+                                client sends the data first (e.g.
+                                HTTP, in contrast to SMTP), because
+                                the server process will not be woken
+                                up unnecessarily before it can take
+                                any action.
+                                </para>
+
+                                <para>If the client also uses the
+                                <constant>TCP_DEFER_ACCEPT</constant>
+                                option, the latency of the initial
+                                connection may be reduced, because the
+                                kernel will send data in the final
+                                packet establishing the connection
+                                (the third packet in the "three-way
+                                handshake").</para>
+
+                                <para>Disabled by default.</para>
+                                </listitem>
+                        </varlistentry>
+

                         <varlistentry>
                                 <term><varname>ReceiveBuffer=</varname></term>
                                 <term><varname>SendBuffer=</varname></term>
                         <varlistentry>
                                 <term><varname>ReceiveBuffer=</varname></term>
                                 <term><varname>SendBuffer=</varname></term>


@@ -571,7 +677,7 @@
 
                         <varlistentry>
                                 <term><varname>PipeSize=</varname></term>
 
                         <varlistentry>
                                 <term><varname>PipeSize=</varname></term>

-                                <listitem><para>Takes an size in
+                                <listitem><para>Takes a size in

                                 bytes. Controls the pipe buffer size
                                 of FIFOs configured in this socket
                                 unit. See
                                 bytes. Controls the pipe buffer size
                                 of FIFOs configured in this socket
                                 unit. See


@@ -704,16 +810,18 @@
                                 finish. If a command does not exit
                                 within the configured time, the socket
                                 will be considered failed and be shut
                                 finish. If a command does not exit
                                 within the configured time, the socket
                                 will be considered failed and be shut

-                                down again. All commands still running,
+                                down again. All commands still running

                                 will be terminated forcibly via
                                 <constant>SIGTERM</constant>, and after another delay of
                                 this time with <constant>SIGKILL</constant>. (See
                                 <option>KillMode=</option> in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
                                 Takes a unit-less value in seconds, or
                                 a time span value such as "5min
                                 will be terminated forcibly via
                                 <constant>SIGTERM</constant>, and after another delay of
                                 this time with <constant>SIGKILL</constant>. (See
                                 <option>KillMode=</option> in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
                                 Takes a unit-less value in seconds, or
                                 a time span value such as "5min

-                                20s". Pass 0 to disable the timeout
-                                logic. Defaults to <varname>TimeoutStartSec=</varname> from the
-                                manager configuration file.</para></listitem>
+                                20s". Pass <literal>0</literal> to disable the timeout
+                                logic. Defaults to <varname>DefaultTimeoutStartSec=</varname> from the
+                                manager configuration file
+                                (see <citerefentry><refentrytitle>systemd-systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
+                                </para></listitem>

                         </varlistentry>
 
                         <varlistentry>
                         </varlistentry>
 
                         <varlistentry>


@@ -730,6 +838,43 @@
                                 option.</para></listitem>
                         </varlistentry>
 
                                 option.</para></listitem>
                         </varlistentry>
 

+                        <varlistentry>
+                                <term><varname>RemoveOnStop=</varname></term>
+                                <listitem><para>Takes a boolean
+                                argument. If enabled, any file nodes
+                                created by this socket unit are
+                                removed when it is stopped. This
+                                applies to AF_UNIX sockets in the file
+                                system, POSIX message queues, FIFOs,
+                                as well as any symlinks to
+                                them configured with
+                                <varname>Symlinks=</varname>. Normally,
+                                it should not be necessary to use this
+                                option, and is not recommended as
+                                services might continue to run after
+                                the socket unit has been terminated
+                                and it should still be possible to
+                                communicate with them via their file
+                                system node. Defaults to
+                                off.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>Symlinks=</varname></term>
+                                <listitem><para>Takes a list of file
+                                system paths. The specified paths will
+                                be created as symlinks to the AF_UNIX
+                                socket path or FIFO path of this
+                                socket unit.  If this setting is used,
+                                only one AF_UNIX socket in the file
+                                system or one FIFO may be configured
+                                for the socket unit. Use this option
+                                to manage one or more symlinked alias
+                                names for a socket, binding their
+                                lifecycle together. Defaults to the
+                                empty list.</para></listitem>
+                        </varlistentry>
+

                 </variablelist>
 
                 <para>Check
                 </variablelist>
 
                 <para>Check