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In the `[ntpd]` section, add any command line options to be passed to `ntpd` when called by [application]*timemaster*. See xref:servers/Configuring_NTP_Using_ntpd.adoc#ch-Configuring_NTP_Using_ntpd[Configuring NTP Using ntpd] for information on using `ntpd`.
In the `[phc2sys]` section, add any command line options to be passed to [application]*phc2sys* when called by [application]*timemaster*. This chapter documents common options and more information is available in the `phy2sys(8)` manual page.
In the `[ptp4l]` section, add any command line options to be passed to [application]*ptp4l* when called by [application]*timemaster*. This chapter documents common options and more information is available in the `ptp4l(8)` manual page.
Save the configuration file and restart [application]*timemaster* by issuing the following command as `root`:
~]# systemctl restart timemaster
Improving Accuracy
Previously, test results indicated that disabling the tickless kernel capability could significantly improve the stability of the system clock, and thus improve the `PTP` synchronization accuracy (at the cost of increased power consumption). The kernel tickless mode can be disabled by adding [option]`nohz=off` to the kernel boot option parameters. However, recent improvements applied to `kernel-3.10.0-197.fc21` have greatly improved the stability of the system clock and the difference in stability of the clock with and without [option]`nohz=off` should be much smaller now for most users.
The [application]*ptp4l* and [application]*phc2sys* applications can be configured to use a new adaptive servo. The advantage over the PI servo is that it does not require configuration of the PI constants to perform well. To make use of this for [application]*ptp4l*, add the following line to the `/etc/ptp4l.conf` file:
clock_servo linreg
After making changes to `/etc/ptp4l.conf`, restart the [application]*ptp4l* service from the command line by issuing the following command as `root`:
~]# systemctl restart ptp4l
To make use of this for [application]*phc2sys*, add the following line to the `/etc/sysconfig/phc2sys` file:
-E linreg
After making changes to `/etc/sysconfig/phc2sys`, restart the [application]*phc2sys* service from the command line by issuing the following command as `root`:
Additional Resources
The following sources of information provide additional resources regarding `PTP` and the [application]*ptp4l* tools.
Installed Documentation
`ptp4l(8)` man page — Describes [application]*ptp4l* options including the format of the configuration file.
`pmc(8)` man page — Describes the `PTP` management client and its command options.
`phc2sys(8)` man page — Describes a tool for synchronizing the system clock to a `PTP` hardware clock (PHC).