[yugabyte#21963] YSQL: Configure clockbound agent

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

@@ -13,28 +13,83 @@ type: docs
 
 Perform the following configuration on each node in the cluster:
 
-- ntp or chrony
+- chrony (ntp)
 - ulimits
 - transparent hugepages
 
 Keep in mind that, although YugabyteDB is PostgreSQL compatible and runs a postgres process, it is not a PostgreSQL distribution. The PostgreSQL it runs doesn't need the same OS and system resources that open source PostgreSQL requires. For this reason, the kernel configuration requirements are different.
 
 In particular, the main YugabyteDB process, the YB-TServer, is multi-threaded. As a result, you don't need to modify settings for shared memory and inter-process communication (IPC), because there is no inter-process communication or shared memory in a multi-threaded process model (all memory is shared by the same process).
 
-## ntp
+## chrony (ntp)
 
-If your instance does not have public Internet access, make sure the ntp package is installed:
+YugabyteDB relies on clock synchronization to guarantee consistency in distributed transactions. Chrony is the prefered NTP implementation for clock synchronization.
+
+To install chrony, run:
 
 ```sh
-$ sudo yum install -y ntp
+$ sudo yum install -y chrony
 ```
 
-As of CentOS 8, `ntp` is no longer available and has been replaced by `chrony`. To install, run:
+### PTP
+
+**Supported Platforms:** AWS
+
+{{<tags/feature/tp>}} Precision Time Protocol (PTP) is a network protocol designed for highly accurate time synchronization across devices in a network. PTP provides microsecond-level accuracy.
+
+PTP relies on a PTP Hardware Clock (PHC), a dedicated physical clock device that enhances time synchronization accuracy. To check if your AWS instance supports PHC, see [AWS PTP Hardware Clock](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configure-ec2-ntp.html#connect-to-the-ptp-hardware-clock).
+
+Configure PTP using the `configure_ptp.sh` script in the bin directory of your YugabyteDB home directory as follows:
 
 ```sh
-$ sudo yum install -y chrony
+sudo bash ./bin/configure_ptp.sh
+```
+
+### Clockbound Agent
+
+{{<tags/feature/tp>}} Although optional, configuring a clockbound agent improves clock accuracy by several orders of magnitude.
+While PHC is beneficial, it is not required for configuring clockbound. However, Chrony is a necessary prerequisite.
+
+Configure a clockbound agent using the `configure_clockbound.sh` script in the bin directory of your YugabyteDB home directory as follows:
+
+```sh
+sudo bash ./bin/configure_clockbound.sh
 ```
 
+After configuring a clockbound agent, you must configure the [YB-TServer](../start-tservers/) and [YB-Master](../start-masters/) servers with the `time_source=clockbound` flag.
+
+If the clockbound agent is configured with PTP, use a more aggressive clock error estimate such as `clockbound_clock_error_estimate_usec=100`.
+
+<details>
+<summary>Verification</summary>
+
+Verify that clockbound is configured properly using
+
+```sh
+systemctl status clockbound
+```
+
+A correctly configured clockbound service reports no errors. Example output with PTP enabled:
+
+```sh
+● clockbound.service - ClockBound
+     Loaded: loaded (/usr/lib/systemd/system/clockbound.service; enabled; preset: disabled)
+     Active: active (running) since Wed 2024-10-16 23:49:38 UTC; 53s ago
+   Main PID: 92765 (clockbound)
+      Tasks: 3 (limit: 22143)
+     Memory: 4.1M
+        CPU: 18ms
+     CGroup: /system.slice/clockbound.service
+             └─92765 /usr/local/bin/clockbound --max-drift-rate 50 -r PHC0 -i eth0
+
+Oct 16 23:49:38 ip-172-199-76-70.ec2.internal systemd[1]: Started ClockBound.
+Oct 16 23:49:38 ip-172-199-76-70.ec2.internal clockbound[92765]: 2024-10-16T23:49:38.629593Z  INFO main ThreadId(01) /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/c>
+Oct 16 23:49:38 ip-172-199-76-70.ec2.internal clockbound[92765]: 2024-10-16T23:49:38.629874Z  INFO ThreadId(02) /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/clock->
+Oct 16 23:49:38 ip-172-199-76-70.ec2.internal clockbound[92765]: 2024-10-16T23:49:38.630045Z  INFO ThreadId(03) /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/clock->
+```
+
+</details>
+
 ## 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.