linux – Multiple core overload on Ubuntu

I have a really strange behavior of the server. I run Apache, MySQL, WordPress on it. And recently, it has had a lot of freezes. MySQL/Apache shows high CPU usage (out of 24 cores – 2400% cpu% according to the htop). At first, I thought that the cause of this was MySQL or Apache. So I’ve tuned the DB, I’ve turned off the Apache, I’ve disabled external access to the server, in case it was a DDOS attack. But the problem remains.

Even when I turn off Apache and MySQL, the problem is still there. Not so critical, but the simple commands use a lot of CPU and take a lot of time to run.

Now my thoughts are that something on the lower level is broken.

Here are the perf top and htop outputs:

perf top htop

Could it be, that the reason is the internal gnu-linux functions? And if so, how can one fix it?