Why do tools expose the value of virtual memory? What value does it have?

RSS is a simple to understand and correlates directly to requirements/availability of physical RAM.

Virtual memory does not seem to map to anything real thus does not indicate any resource requirement or availability.


Virtual memory does map to one resource, albeit one which can be allocated separately for each process (at least for user-space resources): address space. On 32-bit platforms this can easily end up being a limiting factor, and in some scenarios even 64-bit platforms can run out (at least, with the 48-bit limit currently in force on x86).

  • but which resource? And in what way is that resource not already monitored through different means? (disk space/util, swap usage/util, phys memory usage/util)? Also because I do not really receive a max from my system? So I only see the current consumption without any relevance? Jul 27 '21 at 6:52
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    Which resource? I mentioned it in the answer: “address space”. The limit is the same across a given architecture: 32 bits on 32-bit x86, 48 or 56 on 64-bit x86, etc. Jul 27 '21 at 7:17
  • Ah thanks for the clarification. This makes sense, still curious why this is so prominent with various tools under Linux, but I am guessing this might be due to legacy or the fact that Linux is maybe more so used as a server where that metric is more meaningful than with other systems. Jul 27 '21 at 12:09

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