# cgred

cgrulesengd（cgred服务对于的应用）在Redhat 7中，用于按用户管理资源，包含在`libcgroup-tools`工具包中。但是，Redhat 8抛弃了这一工具。

```bash
[root@bogon ~]# rpm -q --changelog libcgroup
* Tue Jan 14 2014 Peter Schiffer <pschiffe@redhat.com> 0.41-1
- resolves: #966008
  updated to 0.41
- removed deprecated cgred service
  please use Control Group Interface in Systemd instead
```

有关评论：

> Looking at version numbers: 0.41-21.el7 and 0.41-19.el8, it is no wonder that dnf can’t raise huge alarm as it should. While both appear “0.41”, they are entirely different beasts, branched ages ago (in 2013, I guess).



# systemd限制用户资源

**注意：本方法不适用于`su`方式切换登录的用户。即，用户使用`GDM`或`ssh`登录时资源使用受此限制。**

## 配置

可以使用`systemd`设置用户的资源配置。例如，假设想限制用户`fairyfar`的CPU使用上限为30%（即单个CPU核的30%），可以按以下步骤配置：

Step 1. 获取用户UID

```bash
[root@bogon ~]# id fairyfar
uid=1002(fairyfar) gid=1002(fairyfar) groups=1002(fairyfar)
```

Step 2. 设置配额

```bash
[root@bogon ~]# systemctl set-property user-1002.slice CPUQuota=30%
```

以上步骤如果报以下错误：

```bash
[root@bogon ~]# systemctl set-property user-1002.slice CPUQuota=30%
Failed to set unit properties on user-1002.slice: Unit user-1000.slice is not loaded.
```

则，先执行以下命令：

```bash
[root@bogon ~]# systemctl start user-1002.slice
```

Step 3. 查看配置情况

```bash
[root@bogon ~]# systemctl cat user-1002.slice

# /etc/systemd/system/user-1002.slice.d/50-CPUQuota.conf
[Slice]
CPUQuota=30%
```

Step 4. 让配置立即生效

```bash
[root@bogon ~]# systemctl daemon-reload
```

可以控制的资源列表详见 [参考文献3](https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html)。请注意：不同参数引入的systemd版本。

## 删除配置

如果systemd版本大于等于229，则可以使用revert命令：

```bash
[root@bogon ~]# systemctl revert user-1002.slice
```

否则，低版本需要手动删除：

```bash
[root@bogon ~]# rm -rf /etc/systemd/system/user-1002.slice.d/
```

删除的路径在`systemctl cat`结果中可以找到，当然也可以有选择性地删除部分配置项。

# 参考

1. [Cgrulesengd is cut in rhel8-based systems](https://forums.rockylinux.org/t/cgrulesengd-is-cut-in-rhel8-based-systems/5062)
2. [systemd, per-user cpu and/or memory limits](https://serverfault.com/questions/874274/systemd-per-user-cpu-and-or-memory-limits)
3. [systemd.resource-control](https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html)