commit c91d9a27fa7f176479d8a8f15bd28ce42a441c03 Author: Stephen Wadeley swadeley@redhat.com Date: Tue Dec 16 21:57:41 2014 +0100
Updates to ptp4l
misc. updates from upstream version
en-US/Configuring_PTP_Using_ptp4l.xml | 52 ++++++++++++++++++++++++++++++-- 1 files changed, 48 insertions(+), 4 deletions(-) --- diff --git a/en-US/Configuring_PTP_Using_ptp4l.xml b/en-US/Configuring_PTP_Using_ptp4l.xml index 0f5174c..e6ad252 100644 --- a/en-US/Configuring_PTP_Using_ptp4l.xml +++ b/en-US/Configuring_PTP_Using_ptp4l.xml @@ -145,6 +145,19 @@ should include:
<section id="sec-Starting_ptp4l"> <title>Starting ptp4l</title> + <para> +The <application>ptp4l</application> program can be started from the command line or it can be started as a service. When running as a service, options are specified in the <filename>/etc/sysconfig/ptp4l</filename> file. Options required for use both by the service and on the command line should be specified in the <filename>/etc/ptp4l.conf</filename> file. The <filename>/etc/sysconfig/ptp4l</filename> file includes the <command>-f /etc/ptp4l.conf</command> command line option, which causes the <systemitem class="service">ptp4l</systemitem> program to read the <filename>/etc/ptp4l.conf</filename> file and process the options it contains. The use of the <filename>/etc/ptp4l.conf</filename> is explained in <xref linkend="sec-Specifying_a_Configuration_File" />. More information on the different <application>ptp4l</application> options and the configuration file settings can be found in the <filename>ptp4l(8)</filename> man page.</para> + +<bridgehead id="bh-Starting_ptp4l_as_a_Service">Starting ptp4l as a Service</bridgehead> + +<para> +To start <application>ptp4l</application> as a service, issue the following command as <systemitem class="username">root</systemitem>: +<screen>~]# <command>systemctl start ptp4l</command></screen> +<!--For more information on managing system services in &MAJOROSVER;, see <xref linkend="chap-Managing_Services_with_systemd" />.--> +</para> + +<bridgehead id="bh-Using_ptp4l_From_The_Command_Line">Using ptp4l From The Command Line</bridgehead> + <para> The <application>ptp4l</application> program tries to use hardware time stamping by default. To use <application>ptp4l</application> with hardware time stamping capable drivers and NICs, you must provide the network interface to use with the <option>-i</option> option. Enter the following command as <systemitem class="username">root</systemitem>: <screen>~]# <command>ptp4l -i <replaceable>em3</replaceable> -m</command></screen> @@ -326,9 +339,24 @@ if <literal>gmPresent</literal> is true, the <systemitem class="protocol">PTP</s <section id="sec-Synchronizing_the_Clocks"> <title>Synchronizing the Clocks</title> <para> - The <application>phc2sys</application> program is used to synchronize the system clock to the <systemitem class="protocol">PTP</systemitem> hardware clock (<acronym>PHC</acronym>) on the NIC. To start <application>phc2sys</application>, where <replaceable>em3</replaceable> is the interface with the <systemitem class="protocol">PTP</systemitem> hardware clock, enter the following command as <systemitem class="username">root</systemitem>: + The <application>phc2sys</application> program is used to synchronize the system clock to the <systemitem class="protocol">PTP</systemitem> hardware clock (<acronym>PHC</acronym>) on the NIC. The <application>phc2sys</application> service is configured in the <filename>/etc/sysconfig/phc2sys</filename> configuration file. The default setting in the <filename>/etc/sysconfig/phc2sys</filename> file is as follows: + <synopsis>OPTIONS="-a -r"</synopsis> + The <option>-a</option> option causes <application>phc2sys</application> to read the clocks to be synchronized from the <application>ptp4l</application> application. It will follow changes in the <systemitem class="protocol">PTP</systemitem> port states, adjusting the synchronization between the NIC hardware clocks accordingly. The system clock is not synchronized, unless the <option>-r</option> option is also specified. If you want the system clock to be eligible to become a time source, specify the <option>-r</option> option twice. + </para> +<para> +After making changes to <filename>/etc/sysconfig/phc2sys</filename>, restart the <application>phc2sys</application> service from the command line by issuing a command as <systemitem class="username">root</systemitem>: +<screen>~]# <command>systemctl restart phc2sys</command></screen> +Under normal circumstances, use <command>systemctl</command> commands to start, stop, and restart the <application>phc2sys</application> service. + </para> + <para> +When you do not want to start <application>phc2sys</application> as a service, you can start it from the command line. For example, enter the following command as <systemitem class="username">root</systemitem>: + <screen>~]# <command>phc2sys -a -r</command></screen> +The <option>-a</option> option causes <application>phc2sys</application> to read the clocks to be synchronized from the <application>ptp4l</application> application. If you want the system clock to be eligible to become a time source, specify the <option>-r</option> option twice. + </para> + <para> + Alternately, use the <option>-s</option> option to synchronize the system clock to a specific interface's <systemitem class="protocol">PTP</systemitem> hardware clock. For example: <screen>~]# <command>phc2sys -s <replaceable>em3</replaceable> -w</command></screen> - The <option>-w</option> option waits for the running <application>ptp4l</application> application to synchronize the <systemitem class="protocol">PTP</systemitem> clock and then retrieves the <acronym>TAI</acronym> to <acronym>UTC</acronym> offset from <application>ptp4l</application>. +The <option>-w</option> option waits for the running <application>ptp4l</application> application to synchronize the <systemitem class="protocol">PTP</systemitem> clock and then retrieves the <acronym>TAI</acronym> to <acronym>UTC</acronym> offset from <application>ptp4l</application>. </para> <para> Normally, <systemitem class="protocol">PTP</systemitem> operates in the <firstterm>International Atomic Time</firstterm> (<acronym>TAI</acronym>) timescale, while the system clock is kept in <firstterm>Coordinated Universal Time</firstterm> (<acronym>UTC</acronym>). The current offset between the TAI and UTC timescales is 35 seconds. The offset changes when leap seconds are inserted or deleted, which typically happens every few years. The <option>-O</option> option needs to be used to set this offset manually when the <option>-w</option> is not used, as follows: @@ -464,8 +492,24 @@ priority1 127 # ptp4l -f /etc/ptp4l.conf</screen> </para> <para> -With hardware time stamping, <application>phc2sys</application> needs to be used to synchronize the <systemitem class="protocol">PTP</systemitem> hardware clock to the system clock: -<screen>~]# <command>phc2sys -c <replaceable>em3</replaceable> -s CLOCK_REALTIME -w</command></screen> +With hardware time stamping, <application>phc2sys</application> needs to be used to synchronize the <systemitem class="protocol">PTP</systemitem> hardware clock to the system clock. +If running <application>phc2sys</application> as a service, edit the <filename>/etc/sysconfig/phc2sys</filename> configuration file. The default setting in the <filename>/etc/sysconfig/phc2sys</filename> file is as follows: +<synopsis>OPTIONS="-a -r"</synopsis> +As <systemitem class="username">root</systemitem>, edit that line as follows: +<screen>~]# <command>vi /etc/sysconfig/phc2sys</command> +OPTIONS="-a -r -r"</screen> +The <option>-r</option> option is used twice here to allow synchronization of the <systemitem class="protocol">PTP</systemitem> hardware clock on the NIC from the system clock. +Restart the <application>phc2sys</application> service for the changes to take effect: +<screen>~]# <command>systemctl restart phc2sys</command></screen> +</para> + + + <para> + To prevent quick changes in the <systemitem class="protocol">PTP</systemitem> clock's frequency, the synchronization to the system clock can be loosened by using smaller <option>P</option> (proportional) and <option>I</option> (integral) constants for the PI servo: +<screen>~]# <command>phc2sys -a -r -r -P 0.01 -I 0.0001</command></screen> + </para> +</section> + <section id="sec-Synchronize_to_PTP_or_NTP_Time_Using_timemaster"> <title>Synchronize to PTP or NTP Time Using timemaster</title> <para>
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