[yugabyte#21963] YSQL: Configure clockbound agent

docs/content/preview/deploy/manual-deployment/system-config.md

@@ -23,6 +23,9 @@ In particular, the main YugabyteDB process, the YB-TServer, is multi-threaded. A
 
 ## ntp
 
+YugabyteDB is a distributed database and relies on clock synchronization to
+provide transaction consistency.
+
 If your instance does not have public Internet access, make sure the ntp package is installed:
 
 ```sh
@@ -35,6 +38,33 @@ As of CentOS 8, `ntp` is no longer available and has been replaced by `chrony`.
 $ sudo yum install -y chrony
 ```
 
+### PHC (PTP Hardware Clock) {{<tags/feature/tp>}}
+
+Hardware clocks are more accurate.
+
+See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configure-ec2-ntp.html#connect-to-the-ptp-hardware-clock
+to check whether your AWS instance supports PHC.
+
+Configure PTP using
+
+```sh
+sudo bash ./bin/configure_ptp.sh
+```
+
+### Clockbound Agent {{<tags/feature/tp>}}
+
+Configuring a clockbound agent improves clock accuracy significantly.
+PHC is desirable but not mandatory.
+Chrony is a pre-requisite.
+
+```sh
+sudo bash ./bin/configure_clockbound.sh
+```
+
+The scripts are packaged in YugabyteDB releases.
+
+Please configure yb-tserver and yb-master with gFlag `time_source=clockbound`.
+
 ## ulimits
 
 In Linux, `ulimit` is used to limit and control the usage of system resources (threads, files, and network connections) on a per-process or per-user basis.