Interpret the top command in ubuntu
I am attaching a screenshot of a top command launched on my server, I cannot understand how to interpret it.
I would like to understand if the RAM is in trouble. Also I see mysql which is over 100% CPU usage, is it correct as reading?
I state that the sites that reside on the server have no difficulty in loading.
The line labeled "Mem" on your output is in reference to your memory. the "total" section is your total memory, the "free" section is the unused and uncached memory, the "used" section is explicitly used memory, and the "buff/cache" section is memory which is currently cached for other applications but can be freed if necessary. As of right now, it looks like you have around 21 GiB of free memory so it should not be an issue.
As for mysql’s CPU usage, how top and similar applications record CPU usage is 100% = 1 thread/core. Judging by how your machine has 8 threads/cores, 165% is nowhere near maximum CPU usage, but 165% usage is quite high for mysql, I would look into what might be causing that, especially if the SQL databases it queries are small.
top is quite bare-bones. I would suggest installing and using
htop wherever possible.