Centos7 释放内存

// 查看内存使用情况
[root@localhost ~]# free -m
// 释放cache
[root@localhost ~]# sync; echo 3 > /proc/sys/vm/drop_caches

清理yum缓存

// 清理/var/cache/yum的headers
[root@localhost ~]# yum clean headers

// 清理/var/cache/yum下的软件包
[root@localhost ~]# yum clean packages

[root@localhost ~]# yum clean metadata