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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.

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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).

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  • 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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