I have got an OpenVZ-based VPS running CentOS 7.4 (Linux hostname 2.6.32-042stab116.2 #1 SMP Fri Jun 24 15:33:57 MSK 2016 x86_64 x86_64 x86_64 GNU/Linux).
The workload is a single Java application. According to top, the java process consumes about 3.3 GB of physical memory out of the 4 GB of usable memory. However, at the same time, the indicated total memory usage is less than 128 MB!
Note that the indicated buff/cache is about 3800 MiB. I've gone through several questions and articles about memory readings in top, but none of them seems to explain this specific situation.
Is it possible that most of the memory attributed to Java as RES, are in fact discardable buffers? Does the kernel keep track of "owning processes" even for cached memory? Or is this just inaccuracy due to virtualization and/or old kernel version?
