optimize ulimit (#2358)

Co-authored-by: abby.huang <[email protected]>
Co-authored-by: Chris Chen <[email protected]>

docs-2.0-en/5.configurations-and-logs/1.configurations/6.kernel-config.md

@@ -4,33 +4,30 @@ This topic introduces the Kernel configurations in Nebula Graph.
 
 ## Resource control
 
-### ulimit precautions
-
-The `ulimit` command specifies the resource threshold for the current shell session. The precautions are as follows:
-
-- The changes made by `ulimit` only take effect for the current session or child process.
-
-- The resource threshold (soft threshold) cannot exceed the hard threshold.
-
-- Common users cannot use commands to adjust the hard threshold, even with `sudo`.
-
-- To modify the system level or adjust the hard threshold, edit the file `/etc/security/limits.conf`. This method requires re-login to take effect.
-
-### ulimit -c
-
-`ulimit -c` limits the size of the core dumps. We recommend that you set it to `unlimited`. The command is:
+You may run the `ulimit` command to control the resource threshold. However, the changes made only take effect for the current session or sub-process. To make permanent changes, edit file `/etc/security/limits.conf`. The configuration is as follows:
 
 ```bash
-ulimit -c unlimited
+# <domain>     <type>      <item>          <value>
+*              soft         core           unlimited    
+*              hard         core           unlimited   
+*              soft         nofile          130000   
+*              hard         nofile          130000
 ```
 
-### ulimit -n
+!!! note
 
-`ulimit -n` limits the number of open files. We recommend that you set it to more than 100,000. For example:
+    The configuration modification takes effect for new sessions.
 
-```bash
-ulimit -n 130000
-```
+The parameter descriptions are as follows.
+
+|Parameter|Description|
+|:--|:--|
+|`domain`| Control Domain. This parameter can be a user name, a user group name (starting with `@`), or `*` to indicate all users.|
+|`type`| Control type. This parameter can be `soft` or `hard`. `soft` indicates a soft threshold (the default threshold) for the resource and `hard` indicates a maximum value that can be set by the user. The `ulimit` command can be used to increase `soft`, but not to exceed `hard`.|
+|`item`| Resource types. For example, `core` limits the size of the core dump file, and `nofile` limits the maximum number of file descriptors a process can open.|
+|`value`| Resource limit value. This parameter can be a number, or `unlimited` to indicate that there is no limit.|
+
+You can run `man limits.conf` for more helpful information.
 
 ## Memory
 

docs-2.0-zh/5.configurations-and-logs/1.configurations/6.kernel-config.md

@@ -4,32 +4,30 @@
 
 ## 资源控制
 
-### ulimit 注意事项
-
-命令`ulimit`用于为当前 shell 会话设置资源阈值，注意事项如下：
-
-- `ulimit`所做的更改仅对当前会话或子进程生效。
-
-- 资源的阈值（软阈值）不能超过硬阈值。
-
-- 普通用户不能使用命令调整硬阈值，即使使用`sudo`也不能调整。
-
-- 修改系统级别或调整硬性阈值，请编辑文件`/etc/security/limits.conf`。这种方式需要重新登录才生效。
-### ulimit -c
-
-`ulimit -c`用于限制 core 文件的大小，建议设置为`unlimited`，命令如下：
+虽然可以用`ulimit`进行资源控制，但是所做的更改仅对当前会话或子进程生效。如果需要永久生效，请编辑文件`/etc/security/limits.conf`。配置如下：
 
 ```bash
-ulimit -c unlimited
+# <domain>     <type>      <item>          <value>
+*              soft         core           unlimited    
+*              hard         core           unlimited   
+*              soft         nofile          130000   
+*              hard         nofile          130000
 ```
 
-### ulimit -n
+!!! note
 
-`ulimit -n`用于限制打开文件的数量，建议设置为超过 10 万，例如：
+    配置修改后会对新的会话生效。
 
-```bash
-ulimit -n 130000
-```
+参数说明如下。
+
+|参数|说明|
+|:--|:--|
+|`domain`|控制域。可以是用户名称、用户组名称（以`@`开头），或者用`*`表示所有用户。|
+|`type`|控制类型。可以是`soft`或`hard`。`soft`表示资源的软阈值（默认阈值），`hard`表示用户可以设置的最大值。可以使用`ulimit`命令提高`soft`，但不能超过`hard`。|
+|`item`|资源类型。例如`core`限制核心转储文件的大小，`nofile`限制一个进程可以打开的最大文件描述符数量。|
+|`value`|资源限制值。可以是一个数字，或者 unlimited 表示没有限制。|
+
+可以执行`man limits.conf`查看更多帮助信息。
 
 ## 内存