Under Linux, you often encounter the problem of excessive buff/cache memory usage, especially when using cloud hosts. Many domains are virtual memory, so if the buff/cache takes up too much, the free space memory is very small. Affect;
The usual memory relationships are:
Ordinary machine: total=used+free
Virtual machine: total=used+free+buff/cache
For example, if you use Aliyun cloud host, it is total=used+free+buff/cache
At this time, you can see that the memory occupied by buff/cache is very large.
At this time, you can use the command to clear the cache memory
echo 1 > /proc/sys/vm/drop_caches
echo 2 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches
The value of drop_caches can be a number between 0-3, representing different meanings: 0: Do not release (system default value) 1: Release page cache 2: Release dentries and inodes 3: Release all caches
In general, executing echo 1 can release most of the cache space!
Reference article: https://zhuanlan.zhihu.com/p/459398220