tikv: document periodic full compaction.

dynamic-config.md

@@ -164,6 +164,7 @@ The following TiKV configuration items can be modified dynamically:
 | `raftstore.apply-max-batch-size` | Raft state machines process data write requests in batches by the BatchSystem. This configuration item specifies the maximum number of Raft state machines that can execute the requests in one batch. |
 | `raftstore.store-max-batch-size` | Raft state machines process requests for flushing logs into the disk in batches by the BatchSystem. This configuration item specifies the maximum number of Raft state machines that can process the requests in one batch. |
 | `raftstore.store-io-pool-size` | The number of threads that process Raft I/O tasks, which is also the size of the StoreWriter thread pool (**DO NOT** modify this value from a non-zero value to 0 or from 0 to a non-zero value) |
+| `raftstore.periodic-full-compact-start-max-cpu` | The CPU usage threshold at which TiKV performs periodic full compaction if full compaction is enabled |
 | `readpool.unified.max-thread-count` | The maximum number of threads in the thread pool that uniformly processes read requests, which is the size of the UnifyReadPool thread pool |
 | `readpool.unified.auto-adjust-pool-size` | Determines whether to automatically adjust the UnifyReadPool thread pool size |
 | `coprocessor.split-region-on-table` | Enables to split Region by table |

tikv-configuration-file.md

@@ -1031,6 +1031,20 @@ Configuration items related to Raftstore.
 + Default value: `0.1`
 + Minimum value: `0`
 
+### `periodic-full-compact-start-times` <span class="version-mark">New in v7.6.0</span>
+
+> **Warning:**
+>
+> Periodic full compaction is experimental. It is not recommended that you use it in the production environment. This feature might be changed or removed without prior notice. If you find a bug, you can report an [issue](https://github.com/pingcap/tidb/issues) on GitHub.
+
++ Sets the specific times that TiKV initiates periodic full compaction. You can specify multiple time schedules in an array. For example, `periodic-full-compact-start-times = ["03:00", "23:00"]` indicates that TiKV performs full compaction daily at 03:00 AM and 23:00 PM, based on the local time zone of the TiKV node. `periodic-full-compact-start-times = ["03:00 +0000", "23:00 +0000"]` indicates that TiKV performs full compaction daily at 03:00 AM and 23:00 PM in UTC time.
++ Default value: `[]`, which means periodic full compaction is disabled by default.
+
+### `periodic-full-compact-start-max-cpu` <span class="version-mark">New in v7.6.0</span>
+
++ Limits the maximum CPU usage rate for TiKV periodic full compaction.
++ Default value: `0.1`, which means that the maximum CPU usage for periodic compaction processes is 10%.
+
 ## coprocessor
 
 Configuration items related to Coprocessor.