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On the ubuntu system monitor there are different types of memory listed: Virtual Memory, Resident Memory, Writeable Memory, Shared Memory & X Server Memory. What are the differences between them, and which reflects the actual RAM usage of the process?

Sorry if it's a newbie question :)

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2 Answers 2

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  • Virtual memory accounts for all the libraries and executable objects that are mapped into your process, as well as your stack space.

  • Resident memory is the amount of memory that is actually in RAM.

  • Writable memory is the amount of address space that your process has allocated with write privileges.

  • Shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies.

  • X server memory is the amount used by the X server for the GUI-session.


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Some definitions and wiki pages:


Shared Memory: The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.

Resident Memory: typically refers to physical RAM installed in the machine

X Server Memory: Self explanatory, the amount of memory the X server is using (X server controls your user interface)

Hope I have clarified some things for you.

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