Mathematical connection between SZ RSS and VSZ in ps o/p?

Question

I wanted to know what mathematical connection is there between the SZ, RSS and VSZ output in ps output e.g.

ps -p 2363 -o sz,rss,vsz

Answer 1

sz and vsz represent the same thing, but sz is in page units, while vsz is in 1024 byte units.

To get your system's page size, you can use:

$ getconf PAGE_SIZE
4096

rss is the subset of the process's memory that is currently loaded in RAM (in kilobytes). This is necessarily smaller than vsz.

So the "mathematical" connections are:

vsz * 1024 = sz * page_size
rss <= vsz