Linux physical memory usage is too high

I tested it on the server with a probe: I found that the physical memory usage is so high, I think the memory is not enough? This is not the case: high memory usage

Tested with a probe on the server:

I found that the physical memory usage is so high, I think the memory is not enough? Actually not like this:

High memory usage is a feature of linux. Linux uses the maximum physical memory to avoid swap space. in addition to the memory occupied by the kernel and applications, the Linux system uses the remaining memory for cache ), the advantage of this is that the memory access latency of running programs is relatively small, reducing unnecessary swap-in and out, and improving the system performance. In this way, even if you use a large amount of memory, the usage will be very high.

I used the free command to view the memory:

Parameter description:

Men:

Total: total physical memory size.

Used: used.

Free: available.

Shared: the total memory Shared by multiple processes.

Buffers/cached: disk cache size.

-/+ Buffers/cached:

Used: total memory used

Free: the actual available memory of the system.

I am not very familiar with this free command. I have studied it in a few days.