Where is the memory used?

Question

Django

Good day to all.
Interested in such a question, a physical server with 16GB of memory.
Running django + postgre + gunicorn + supervisor + nginx.
The number of workers is 9 (for corei7).
I watch free -m:

total       used       free     shared    buffers     cached
15945      15770        175        147        389      13999
-/+ buffers/cache:       1381      14564
Swap:         4879          0       4879

That is free only 175Mb
Why is this happening?
Perhaps it is better to run through UWSGI?
Thank you in advance

Answer 1

wiki.enchtex.info/practice/nginx/cache

Answer 2

Free: 14564 Mb
line -/+ buffers/cache:
the rest are caches/buffers that do not prevent applications from allocating memory.

Answer 3

https://github.com/pixelb/ps_mem actual memory consumption of processes