Why is the use of OP going off scale on VDS hosting?

Question

symfony

Welcome all. Please help me deal with the following situation:
1. I bought VDS-hosting with a tariff, where OP is 512Mb.
2. Installed Ubuntu 12.04.5, nginx, php5-fpm, mariadb, Symfony 2.
3. When I restarted with nginx, php5-fpm and mysql configuration settings, I accidentally saw memory consumption - 238% ( ~1350M ). During subsequent work with hosting, I rebooted the server many times for various needs, but memory consumption did not decrease. When stopping nginx, php5-fpm, mariadb, the memory load is 96% (~491Mb). Processor - 0%.
Question: does the nginx, php5-fpm, mariadb bundle really consume so much memory with their usual configs? This is despite the fact that the site on Symfony 2 does not yet function on this server. Tell me (if you need more accurate current characteristics, I'll show you) what and where can and should be optimized in conjunction with nginx, php5-fpm, mariadb, or just stupidly start running into a hoster? Thank you in advance for your help.

Answer 1

276M is occupied out of 512M Of
these 276M, the file cache occupies 110MB (it will be freed if programs need memory) in total 160 megabytes out of 512 are occupied.
In general, the norms.

Answer 2

show the output of the "sudo top" command

Answer 3

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- waiting for comments. Thank you.